THE SINNEMAHONNING COOPERATIVE WEED MANAGEMENT AREA (SIPMA) GETS TO WORK. T.J. Meyer, J. Zoschg, and M.A. Bravo*, Pennsylvania Department of Agriculture, Harrisburg, PA (1)


Cooperative Weed Management Areas are growing in the Northeast.  In 2008, with the support of the Pennsylvania (PA) Department of Agriculture, the PA Department of Conservation and Natural Resources, the PA Invasive Species Council, the United States Department of Agriculture Forest Service and others, a group of concerned land managers in North central Pennsylvania, formed a Cooperative Weed Management Area (CWMA) called the Sinnemahoning Invasive Plant Management Area (SIPMA), to work together to control noxious and invasive weeds.

Invasive and noxious plant species are a growing threat to biodiversity in the hardwood forests of Northern Central Pennsylvania, and it is still possible to control many species that are not yet common or widespread. The Sinnemahoning Cooperative Weed Management Area – the Sinnemahoning Invasive Plant Management Area (SIPMA) is working together to perform early detection and rapid response to weed populations in the watershed, monitor treated sites, and to educate the general public and the landowners about the problem. Various funding sources have supported the start up of the organization since 2008. In early 2011, funds were granted to hire a CWMA coordinator, who will be dedicated to implementing the goals of the CWMA partners. The SIPMA is composed of public agencies, private landowners, and non-profits.  

Since 2008, The Bucktail Watershed Association (BWA), has been writing grants and obtaining funds for managing weed control projects, working to eradicate localized populations of Japanese knotweed (Polygonum cuspidatum), mile-a-minute vine (Polygonum perfoliatum) and common buckthorn (Rhamnus cathartica). The PA Department of Agriculture has assisted landowners with survey, detection and control of two state noxious weeds of limited distribution in the SIPMA area: mile-a-minute, and the federal noxious weed goatsrue (Galega officinalis).  PDA field staff have assisted 41 landowners with the identification, detection and control of 24 acres of private lands adjacent to Sinnemahoning State Park in Cameron and Potter Counties that are infested with mile-a-minute. Herbicide reference plots (meter square) indicate that 0, 28, and 8 seedlings emerged in the same area where the previous year’s data detected 206, 261, and 114 respectively - these reference plots having been treated consecutively in 2007 and 2008. By contrast a control plot yielded 243 seedlings in 2011 down from 1,184 seedlings in 2010 – indicating that environmental conditions are also contributing to mile-a-minute demise. Observations of the beetle Rhinocominus latipes feeding indicate mile-a-minute cover dropped from 70% at one release site in August of 2010 to 5% cover as of September 2011.

The Cameron County Conservation District has been writing grants for weed control projects and is doing education and outreach in schools and to the general public. Other state agencies are also working with the SIMPA to control localized populations of key species. The PA Game Commission is controlling buckthorn on state game lands in the SIMPA region. There are two PA Department of Conservation and Natural Resources Forests, the Elk and Susquehannock, as well as the Sinnemahoning State Park, who are working to control Japanese barberry, (Berberis thunbergii), Japanese knotweed and mile-a-minute vine, as well as some very limited populations of goatsrue discovered in recent years. 

GIANT HOGWEED ERADICATION IN PENNSYLVANIA AND THE UNITED STATES. M.A. Bravo*, I.D. Bowers, and J. Zoschg, Pennsylvania Department of Agriculture, Harrisburg, PA (2)


 In 1983, the United States Department of Agriculture Plant Pest Health Inspection Service (USDA-APHIS) declared the plant a federal noxious weed and targeted giant hogweed for eradication nationwide.  As of 2011, GH had been found in 18 states and in Canada. It was added to the PA Noxious Weed Control List in 2000. The Pennsylvania Department of Agriculture (PDA) and USDA/APHIS launched the GH Hotline in 1998 and created a national giant hogweed campaign to promote awareness of this poisonous plant and created a PA state hotline (1-877-464-9333).

Since the PA state program began, 453 sites have been found in 17 PA counties. The targeted eradication program has been very successful and 325 of these sites have been declared eradicated.  More than 55% of the Pennsylvania populations are found in Erie County.  Nearby sites are still known in Crawford, Mercer, McKean, Venango, and Warren Counties. Isolated sites are also known from Elk, Potter, Butler, Blair, Huntingdon, Carbon, and Wayne counties. PA also assists neighboring states with site specific eradication programs.

The goal for eradiation of this federal noxious weed from Pennsylvania and neighboring states requires field staff to monitor sites every year for at least 3 consecutive years to ensure the seedbank has been exhausted. Each season, between May and August, field staff in the Noxious Weed Program are regularly surveying active sites; assisting property owners with control measures (chemical and mechanical); monitoring released sites; and responding to the hotline calls. For Pennsylvania, these continued surveys detected 11 new sites of giant hogweed in 2011, that are, for all intents and purposes relate to existing sites on an adjoining landowner’s property. In all only 74 (16%) of the 453 known sites in the state remain active.

With the cooperation of the PA Dept. of Agriculture and USDA-APHIS, OHIO has been treating several sites in Ashtabula and Lake Counties. In 2011 a new site was found in Cuyahoga County. Ohio will continue to monitor all known sites until GHW is eradicated and relies heavily on the local townships and municipalities for their help in reporting and controlling GHW whenever possible. Maine reports that Giant hogweed is not prevalent with less than 25 known sites in the state, and new sites have been reported each year. In New York, the giant hogweed program is in its 3rd field season with more than 800 sites surveyed, monitored or controlled by the NYDEC program in 2010. As of 2011, more than 900 sites have been detected in 35 counties since the media began extensively reporting on the location of infestations.

COMPARING HERBICIDE TOLERANCES OF RARE AND COMMON PLANTS IN LANCASTER COUNTY, PA. I.M. Graham*, J. Egan, and D. Mortensen, Pennsylvania State University, University Park, PA (3)


Plant diversity contributes to valuable services in agroecosystems, but has been in decline in many agricultural regions over the past half century.  While this decline has often been attributed to escalating use of chemical herbicides, other changes in farming practice including the clearing of semi-natural habitat fragments have occurred over the same period and confound the influence of herbicides.  Recent innovations in biotechnology will likely result in further changes in the quality and quantity of herbicide use.  Understanding the extent to which herbicides shape plant communities in agricultural landscapes therefore remains an open and highly relevant area of research.  If herbicides are in fact a key factor shaping agricultural plant diversity, we would expect to see the signal of past herbicide impacts in the current plant community composition of an intensively farmed region, with common, successful species more tolerant than rare or declining species.  By combining data from an extensive field survey of plant diversity in Lancaster County, PA with greenhouse herbicide bioassay experiments, we tested the hypothesis that common species possess higher herbicide tolerances than rare species.  Our experiments included congeneric contrasts with the common species Asclepias syriaca, Bidens frondosa, Elymus riparius, Polygonum convolvulus, and Verbena utricifolia and the rare species A. tuberosa, B. cernua, E. hystrix, P. lapathifolia, and V. hastata.  We exposed each species to four doses of the herbicides atrazine, dicamba, and glyphosate plus a water control. Plants were treated 4-6 weeks after emergence and assessed 28 days after treatment for clonal shoot production in Asclepias and Elymus, flower production in Verbena and above ground biomass in all genera. Based on EC50 for clonal shoots, flowers, or biomass, preliminary analysis of our data did not indicate a statistically significant difference in tolerance between rare and common species for any of the genera for any of the herbicides.  These results suggest that plant communities in agricultural landscapes may be more strongly shaped by growth rate, life history traits, land use patterns than herbicide tolerances.



Dow AgroSciences is committed to stewardship of the Enlist™ Weed Control System.  Enlist Duo™ featuring Colex-D Technology™ will be a new herbicide solution with reduced potential for drift and low volatility of 2,4-D.  The types of nozzles used in an application will also greatly impact the potential for drift.  Dow AgroSciences will provide comprehensive stewardship guidance for deploying this technology system along with recommendations for the types of nozzles to use that reduce potential for drift. 

 In 2011, field research trials were conducted under two separate protocols to evaluate crop tolerance and weed efficacy results using XR TeeJet©, TurboTeeJet©, AIXR TeeJet© and TurboTeeJet© Induction spray nozzles delivering spray droplet sizes ranging from fine to ultra coarse.  In the crop response study, these nozzles were used to apply the high- end 2X use rate of the lead premix formulation of new 2,4-D choline + glyphosate, plus or minus  2.5% v/v AMS at 7.5 and 15 gallons per acre spray volume over-top Enlist™ corn stacked with SmartStax® and Enlist soybean stacked with glyphosate tolerance.  Likewise, these nozzle types at 10 gallons per acre spray volume, were used to apply multiple, sub 1X to low- end 1X use rates of the new 2,4-D choline+glyphosate premix, to evaluate the effect of drift reducing nozzles on weed control over-top Roundup Ready® 2 Corn.  Results from these trials support previous technical assumptions that nozzle tip selection criteria for reduced drift can be obtained without effect on crop tolerance or weed control. 


™ Enlist, Enlist Duo and Colex-D are trademarks of Dow AgroSciences LLC.  Components of the Enlist Weed Control System have not yet received regulatory approvals; approvals are pending. Enlist Duo herbicide is not registered for sale or use. The information provided here is not an offer for sale. Always read and follow label directions.©2011 Dow AgroSciences LLC

 © XR TeeJet, TurboTeeJet, AIXR TeeJet and TurboTeeJet Induction are trademarks of                 Spraying System Co.

SmartStax® multi-event technology developed by Monsanto and Dow AgroSciences LLC.

Roundup Ready® Corn 2,  SmartStax and the SmartStax logo are trademarks of                           Monsanto Technology, LLC

MODELING OF VOLATILITY OF 2,4-D ESTER, DMA AND CHOLINE FORMULATIONS. B.D. Olson*, D.E. Hillger, P. Havens, J.A. Huff, R.B. Lassiter, and J.S. Richburg, Dow AgroSciences LLC, Geneva, NY (5)


Dow AgroSciences conducted multi-year field trials (2010- 2011) at four different locations to evaluate the volatility of a new form of 2,4-D on both a comparative and quantitative basis.  Large, multi-hectare field plots were treated with a single application of either 2,4-D ethylhexyl ester, 2,4-D dimethylamine salt or a novel 2,4-D choline salt.  Air concentrations and sensitive plant injury were measured in a spoke and wheel fashion at distances of 5 and 15-m from the field edge, respectively.  Volatility flux estimates, based upon back calculation procedures, suggest the reduction of volatile emissions from the new 2,4-D choline formulation was an order of magnitude or more lower than other 2,4-D forms, with no visible injury to sensitive plants placed around the field.   When 2,4-D choline volatility flux estimates are integrated into the ISCST and CALPUFF air dispersion models, the estimated exposures to 2,4-D vapors were much lower than the levels that would affect sensitive vegetation.



Dow AgroSciences is committed to stewardship of the Enlist™ Weed Control System.  Enlist DuoTM herbicide featuring Colex-DTM technology will be a new herbicide solution with reduced potential for drift,ultra low volatility, and reduced odor..  A key component of Colex-D Technology is new 2,4-D choline.  Qualitative and quantitative laboratory studies have been reported that clearly show lower volatility of 2,4-D choline compared to 2,4-D ester and 2,4-D dimethylamine formulations (DMA).  Large 0.5-5.5 acre field studies using both quantitative and qualitative methods have validated the laboratory studies.  For demonstration and training of sales representatives, growers, dealers and applicators, it is desirable to develop reproducible small plot methodology for comparing performance of various formulations.

Previous work at Dow AgroSciences has shown that the use of plastic row covers, referred to as low tunnel structures, will trap volatile emissions from treated surfaces, concentrate the vapors close to the row crop canopy and demonstrate the volatility effects  of different formulations on susceptible plant species.   Moveable low tunnel structures were constructed with ˝” metal electrical conduit and 1 inch by 4 inch by 12 ft sideboards.   A 5 ft long conduit was bent at 90 angles to result in 18 inch tall by 24 inch wide “u-shape”.  The bottoms of five conduit u-shapes spaced 3 ft apart were connected to the inside of two boards.  Clear, 1 mm plastic was stretched over the structure and attached to the conduit with ˝ copper tubing hangers.  Flats (10.5 x 21 x 2.5 inch) filled with sand were treated with herbicide at a location at least 1000 ft from the cotton field to avoid any potential physical drift.  Applications were made with a back pack CO2 sprayer with three TT11002 nozzles spaced at 20 inches delivering 15 GPA. 

A series of experiments were conducted in 2011 to evaluate various factors in the experimental design to optimize results.   The first experiment  evaluated crop injury resulting from 2,4-D DMA applied at 1120, 2240 and 4480 g ae/ha.  After application, three treated flats were placed in the center of a 24 ft by 30 inch low tunnel structure in two reps.  After 48 hours the low tunnels and flats were removed.  A second experiment evaluated the impact of the length of exposure (24 vs 48 hours) on crop injury for 2,4-D DMA at 2240 and 4480 g ae/ha.   A third experiment evaluated the effect of area treated by comparing 3 flats treated with 2,4-D at 2240 g ae/ha to 1.5 flats treated with 2,4-D DMA at 4480 g ae/ha and 3 flats treated with 2,4-D DMA at 4480 g ae/ha.  A fourth experiment evaluated the effect of soil type (silty clay loam vs sand) on volatility injury from 2,4-D DMA.  In the fourth experiment , plots were 2.5 x 12 ft with a single treated flat placed in the middle of the plot.  Results from these experiments show that 2,4-D DMA rate has minimum impact on level of injury under these conditions and that most of the injury results from volatility that occurred in the first 24 hours.   The treated area can be minimized as long as the total amount of product applied is the same as that applied to larger area.   Injury to cotton from volatility of 2,4-D DMA was not significantly impacted by the soil type.  Results from these experiments validate the use of low tunnel structures to assess 2,4-D volatility on susceptible crops.

™ Enlist, Enlist Duo, and Colex-D Technology are trademarks of Dow AgroSciences LLC. Components of the Enlist Weed Control System are pending regulatory approvals. Enlist Duo herbicide is not registered for sale or use. The information provided here is not an offer for sale. Always read and follow label directions.©2011 Dow AgroSciences LLC



Methiozolin (MRC-01) has controlled annual bluegrass on golf putting greens in several research trials in the US and other countries but little is known about the method of selectivity between creeping bentgrass and annual bluegrass.  The proposed mode of action of methiozolin is a cell wall biosynthesis inhibitor and research is currently working on further elucidating this mode of action and the mechanism of selectivity.  In this study, we evaluated the effect of direct root exposure to methiozolin rates in nutrient solution on creeping bentgrass and annual bluegrass root regeneration in an aeroponics system. 

Studies were conducted in greenhouse and growth chamber environments with day/night temperatures of 29/21 C and supplemental light supplied by high-efficiency T-5 lamps generating 325 PAR on a 14 hr photoperiod.  Two aeroponics systems were used in replicating treatments.  The first consists of large chambers housing 6 annual bluegrass plants and 6 creeping bentgrass plants in a random arrangement.  The system uses a sump containing nutrient water that is pumped into another chamber where spray nozzles mist plant roots suspended from the chamber lid.  Excess nutrient drains out the bottom of the upper chamber back into the sump.  Plants started as single tiller shoots placed in foam plugs.  After 5 weeks, plants had 53 to 135 tillers and roots were 30 cm.  The plants were separated into size classes that were uniformly distributed between chambers.  Plant roots were cut to 2 cm and the study was initiated.  Nutrient sumps contained 38 L of nutrient water and were modified to contain methiozolin at 8, 16, 32, 65, 196, and 328 ppb.  These concentrations represent field application rates between 2.5 and 500 g ai/ha.  A comparison treatment included bensulide at a concentration to mimic the field application rate of 9 kg ai/ha.  After 21 days the first replicate was completed and data from the 6 subsample plants showed that a rapid drop in percentage root growth (% of NTC) occurred between 2.5 and 25 g ai/ha methiozolin and then percent reduction leveled at approximately 85% reduction of annual bluegrass root length and 60% reduction of creeping bentgrass root length.  The system was cleaned and prepared for the second replication and it was noted that plant roots would not grow in the chambers that previously held the higher methiozolin rates.  It became obvious that scrubbing and pumping with ammonia water was not sufficient to clean plasticware of methiozolin because methiozolin is not water soluble.  It was recommended we clean the system with an organic solvent such as methanol.  Before doing so, we allowed plants to grow in the system for three months to evaluate root regeneration.  After three months, creeping bentgrass roots showed a clear advantage over annual bluegrass.  In fact, many annual bluegrass plants died while creeping bentgrass plants continued to increase in size.  In the chamber that contained 338 ppb methiozolin before cleaning, no bentgrass or annual bluegrass roots were longer than the 2 cm cut length after 3 months.  A new system was created to allow for simultaneously replicated treatments.  This system uses smaller sumps of 500 ml capacity and pumps nutrient solution in tubing to dribble down plant roots rather than spraying plant roots with nutrient.  Results from this second replicated experiment are not available at the time of this writing and will be discussed at the annual meeting.  At this time, it appears methiozolin has a significant impact on root growth of both creeping bentgrass and annual bluegrass but there appears to be significantly more reduction of annual bluegrass than of creeping bentgrass.  We are not able to make conclusions at this time but a preliminary assumption is that differential root response to methiozolin may be one mechanism that allows for competitive displacement of annual bluegrass by creeping bentgrass on putting greens treated with methiozolin.

CROP ROTATION: SEQUENCE BENEFITS AND PROBLEMS . C.L. Mohler*, Cornell Univeristy, Ithaca, NY (8)


Much information on the problems and benefits associated with particular crop sequences can be found in the scientific literature of various disciplines.  Until recently, this information was highly scattered, but it was collated in an appendix in the recently published book Crop Rotation on Organic Farms: A Planning Manual, Charles L. Mohler and Sue Ellen Johnson, eds., NRAES, 2009.  This table has now been reprinted as an attractive poster which is available from NRAES (web address).  The chart shows potential problems and benefits of following a crop shown on the left with a crop shown at the top.  Most vegetable crops, field crops and cover crops grown in the Northeast are included in the chart. The letters in the body of the chart indicate potential problems: D, disease; W, weeds; I, insects; N, nutrients; S, soil structure; C, other agronomic problems such as timing issues.  A minus sign following a letter indicates that the sequence is potentially beneficial.  A booklet of notes shipped with the poster explains in more detail the nature of the problem or benefit indicated in the chart along with the source reference.  The poster is useful in extension work as a means for motivating discussions of crop rotation and is invaluable for farmers as an at-a-glance reference when planning the season’s plantings.

HERBICIDE EVALUATION FOR WATERMELON GROWN WITH PLASTICULTURE. S.A. Mathew*, B.A. Scott, and M.J. VanGessel, University of Maryland, Cambridge, MD (9)


Herbicide evaluation for watermelon grown with plasticulture. S. A. Mathew, B. A. Scott, and M. J. VanGessel, University of Maryland Extension, Cambridge, MD and University of Delaware, Georgetown, DE

Broadleaf and grass weed species growing between the rows of plastic mulch for commercial watermelon production in Mid-Atlantic pose a challenge. Growers typically use residual herbicides tank mixed with non-selective herbicide applied using hooded sprayers for weed control in row middles of plastic mulch.  The herbicide application time is usually two weeks after transplanting or before vines start to run off of the plastic whichever comes first.  The herbicide options for watermelons are limited, but flumioxazin has been recently labeled for this use.  This study was initiated to evaluate crop safety and weed control with flumioxazin as a component of herbicide programs for row middles of watermelon.

The study was conducted between 2010 and 2011 at two locations on Delmarva Peninsula. The study locations were University of Delaware’s Research and Education Center near Georgetown, DE and University of Maryland’s Lower Eastern Shore Research and Education Center, Salisbury Facility.  Herbicide treatments were evaluated for weed control efficiency and watermelon crop injury.  Residual broadleaf herbicides included flumioxazin, fomesafen, clomazone, and halosulfuron; and these were all applied in combination with ethalfluralin for grass control. All treatments included paraquat, except untreated check, for non-selective control.  Treatments were replicated three times and arranged in a randomized complete block design.  Plot size was one watermelon row (rows were 8 feet apart), 35 feet long.  Both sides of the watermelon rows were sprayed with the herbicide treatment using a hooded sprayer. Standard triploid watermelon variety “Millionaire” was used for the study at both locations.

In 2010 at UM-LESREC or UD-REC, there were no differences between treatments for watermelon injury or yield.  Watermelons at Delaware location showed slight leaf burn and stunting but were not consistent across treatments.  Paraquat alone provided at least 85% weed control, and there were no differences in weed control between the various residual herbicide treatments in either location during 2010.

Weed control in 2011, at UD-REC was similar for all treatments with residual herbicides except clomazone plus ethalfluralin which resulted in lower morningglory species and large crabgrass control.  At UM-LESREC, this same treatment resulted in less control of large crabgrass and smooth pigweed.

In 2011 at UD-REC, flumioxazin treatments resulted in higher levels of watermelon injury 6 days after treatment (10 to 13%), than other treatments.  However, treatments with flumoxazin resulted in the highest yields.  At UM-LESREC, there were no differences between treatments for watermelon injury or watermelon yield.

Early-season injury of watermelon often does affect yields.  Paraquat alone provided (>75% control) good control of initial weed flush, residual herbicides were often needed for weed control through the harvest season.  Season-long weed control is important for efficient harvest and ease of plastic removal.  Flumioxazin could provide improved morningglory and large crabgrass control, provided the growers were willing to accept the risk of slightly higher crop injury.



Annual bluegrass is the most prevalent weed problem on creeping bentgrass golf putting greens.  There are no effective selective controls to manage it well.  Most superintendants rely on plant growth regulators to slow the growth of annual bluegrass and effectively suppress seedhead production.  A plant growth regulator program requires repeated applications throughout the season to maintain control.  For example paclobutrazol and trinexapac ethyl are typically applied together 6 to 8 times at three week intervals beginning in late spring and continuing into the fall.  Patents recently expired for both paclobutrazol and trinexapac ethyl and new formulations have been registered. 

The objective of this study was to compare PGR programs using new generic formulations of paclobutrazol and trinexapac ethyl compared to the original proprietary products.  Studies were established as randomized complete block designs at two sites in 2011, Draper Valley Country Club in Draper, VA and Spotswood Country Club in Harrisonburg, VA.  Trials were initiated May 13th and May 14th, respectively and treatments were repeated every three weeks.  Treatment programs included the following:  1) paclobutrazol (Trimmit 2SC) applied twice in spring and three times in fall at 0.28 kg ai/ha and three times in summer at 0.14 kg ai/ha plus trinexapac ethyl (Primo Maxx) at 0.05 kg ai/ha; 2) paclobutrazol (Tide Paclo) applied at same rates and timings as treatment 1 with the exception that the summer addition of trinexapac ethyl consisted of the product T-Nex instead of Primo Maxx; 3) same as treatment 1 except all paclobutrazol rates are reduced by half; 4) same as treatment 2 except all paclobutrazol rates are reduced by half; 5) flurprimidol (Cutless 50WP) applied twice in spring and three times in fall at 0.3 kg ai/ha and three times in summer at 0.15 kg ai/ha plus trinexapac ethyl (Primo Maxx) at 0.05 kg ai/ha.  A nontreated check was also included and treatments were replicated three times at each site.  Annual bluegrass cover was 35-47% at Draper when the trials were initiated.  In mid July, annual bluegrass cover at Draper was 62% in the nontreated check and 13 to 27% and equivalent for both formulations at the low paclobutrazol rate and 4.0 to 4.7% and equivalent in both formulations at the high paclobutrazol rate and the flurprimidol program.  Thus, there was a significant rate response and all treatments reduced annual bluegrass cover compared to the nontreated control but product formulation did not significantly impact annual bluegrass cover.  Turf injury was never evident and quality was never significantly different from the nontreated check at Draper.  Annual bluegrass cover ranged from 58-67% at Spotswood at trial initiation.  On June 23, the nontreated control had 50% annual bluegrass cover and all treatments significantly reduced cover to 21 to 33% with no differences between treatments.  In July and August, no differences were noted in annual bluegrass cover at Spotswood.  Although creeping bentgrass was never injured by various treatment programs, on June 15 turfgrass quality was significantly decreased by both high-rate paclobutrazol programs due to phytotoxicity to annual bluegrass.  On June 23, all treatment programs significantly increased turf quality compared to the nontreated control, presumably due to the addition of trinexapac ethyl for summer treatments.  These programs are undergoing fall treatments now and fall ratings will be discussed at the annual meeting.

EFFECT OF WEED REMOVAL TIMING IN CORN AS INFLUENCED BY NITROGEN SOURCE AND RATE. W.J. Everman*, A. Knight, and J. Hinton, North Carolina State University, Raleigh, NC (11)


Timely weed control and adequate nitrogen supply are both necessary to maximize corn grain yield and economic return. A field study was established in 2011 at locations, the Central Crops Research Station near Clayton, NC and the Upper Coastal Plain Research Station near Rocky Mount, NC to investigate the effect of nitrogen source and rate on critical time of weed removal and grain yield. Three nitrogen sources (urea ammonium nitrate, sulfur coated urea, and chicken litter), four nitrogen preplant application rates (0, 67, 134, and 202 kg N ha-1) and 2 weed removal timings (0, 7.5, and 15 cm) were evaluated. Weed removal timings were defined by weed canopy height to include control when weeds were 7.5 and 15 cm tall. Weed species present and evaluated consisted of Palmer amaranth (Amaranthus palmeri) and large crabgrass (Digitaria sanguinalis). Plots were maintained weed free after each weed removal timing. At each weed removal timing, biomass samples were collected by species and fresh and dry weights recorded. Total nitrogen will also be measured in each weed species using the Dumas method. Yield was determined at 15% grain moisture.

A NEW POCKET SCOUTING GUIDE FOR AQUATIC WEEDS. B. Lassiter, R.J. Richardson*, and G. Wilkerson, North Carolina State Univ., Raleigh, NC (12)


A new identification guide for common aquatic plants of the southern Mid-Atlantic region of the United States has been created by North Carolina State University.  This guide is designed to be field portable; it will fit in a large pocket and is printed on water tolerant stock.  Color photographs, comparison tables, line drawings, and text descriptions of approximately 60 species are included to aid users in identification.  These species include selected algae, ferns, and vascular plants that are common and/or problematic.  Both invasive species and common natives are included.  Sample pages and ordering information for this guide will be displayed.



Hairy vetch (Vicia villosa Roth) is a legume cover crop commonly used in the Northeast region. It can be beneficial as a nitrogen fixer, while providing weed suppression and erosion control. Although the benefits of hairy vetch can be significant, adoption by some producers has been limited due to the perception that it can become an invasive weed. Hairy vetch is known to contain hard seed which can result in persistent seedbanks. Persistent seed and the vining competitive growth habit of the plant can lead to both crop yield loss and harvesting difficulties, particularly in organic systems. The goal of this study was to quantify seedbank persistence and seedling emergence of hairy vetch over time as influenced by soil burial depth, mechanical seed scarification and plant cultivar. Experiments were conducted from 2009 to 2011 at the Russell Larson Research and Education Center in Centre County, PA and the Beltsville Agricultural Research Center in Beltsville, MD. Five hundred seeds of two hairy vetch cultivars (Albert Lea and Groff Early Cover) were placed at the bottom of mesh cages at two burial depths of 3 and 15 cm. Half the seeds were mechanically scarified, while the other half were not (scarified vs. non-scarified). The experiment was structured as a split-split-plot with four replications and it was repeated over time. Emerged seedlings were counted approximately every two weeks throughout the study and cages were excavated at three time intervals (6, 12, 18 months). Intact seeds were collected and quantified for each excavation date and tested for viability. Results showed that scarified treatments contained no viable seed after six months at both locations, while non-scarified treatments had a maximum of 8% remaining. Nearly all observed hairy vetch emergence occurred within six months. Seed at the 15 cm depth showed decreased emergence at both locations and tended to increase seed bank persistence compared to the 3 cm depth. These results suggest that mechanical scarification of hairy vetch prior to planting has potential to eliminate hard seed and seed bank persistence without lowering emergence potential and could be used as a management tool.

IMPACTS OF INVASIVE AMBROSIA ARTEMISIIFOLIA ON SOIL ENZYME ACTIVITY AND FERTILITY. Q. Zhong*, X. Junfang, Q. Guoming, Z. Jia-en, M. Danjuan, and A. DiTommaso, South China Agricultural University, Guangzhou, Peoples Republic (14)


The rapid spread of Ambrosia artemisiifolia L. (common ragweed) in China has been purported to cause substantial deleterious effects to the structure, biodiversity, and function of ecosystems colonized. The study reported herein was undertaken to better understand the impacts of A. artemisiifolia invasion on soil microbial communities and related microbiological parameters. Soils were sampled from four experimental areas including: (1) an historically-invaded area, (2) newly-invaded area, (3) grassland area, and (4) native-plant area from October 2009 to July 2010. Soil chemical properties, enzyme activities, microbial biomass and functional diversities based on community level physiological profile (CLPP) assays with BIOLOG plates were determined. A. artemisiifolia invasion altered chemical and soil microbial community properties. In areas with longer A. artemisiifolia invasion history, soil microbial community performance was enhanced and appears to have improved soil fertility and accelerated soil carbon, nitrogen, and phosphorus cycles. In contrast, the microbial community in invaded areas showed relatively lower efficiency in carbon source utilization, especially for carbohydrates and amino acids. The improvement of soil fertility as well as microbial community functioning in invaded soils may be beneficial for the successful invasion and growth of A. artemisiifolia in new habitats.

PHYSIOLOGICAL AND MORPHOLOGICAL RESPONSES OF INVASIVE AMBROSIA ARTEMISIIFOLIA TO DIFFERENT IRRADIANCES. M. Danjuan, Q. Zhong*, Q. Guoming, Z. Jia-en, X. Junfang, and A. DiTommaso, South China Agricultural University, Guangzhou, Peoples Republic (15)


The southward spread of A. artemisiifolia (common ragweed) in China in recent years has become a serious environmental problem. To better understand how A. artemisiifolia acclimate to these new habitats, we compared irradiance plasticity, capture ability, and adaptability of A. artemisiifolia and Urena lobata L., a native co-occurring species. We also explored relevant underlying mechanisms for response differences between the two species and effects of varying irradiance conditions on their antioxidant enzyme systems. We hypothesized that A. artemisiifolia will display higher plasticity than U. lobata in traits pertaining to biomass partitioning, growth, and photosynthesis and have unique strategies to regulate how the activities of its antioxidant enzymes acclimate to varying irradiances. To test this hypothesis, we conducted an experiment from November 2009 to June 2010 using seedlings of A. artemisiifolia and U. lobata grown under four irradiance regimes (10%, 30%, 55%, and 100% irradiance). A. artemisiifolia showed significantly higher total biomass, total leaf area, specific leaf area (SLA), relative growth rate (RGR), net assimilation rate(NAR) but lower root mass fraction (RMF) and support organ mass fraction (SMF) than U. lobata in sun and partial shade. It also exhibited higher light-saturated photosynthetic rate (Pmax), light saturation points (LSPTs), dark respiration rate (Rd) except at 10% irradiance. A. artemisiifolia had a greater capacity for scavenging oxygen radicals at higher irradiance by significantly enhancing catalase (CAT) activities and peroxidases (POD), reduced gluthathione (GSH) and tea polyphenol (TP) content though superoxide dismutase (SOD) content was not greatly improved. Lower irradiance reduced antioxidant metabolism of both species, especially A. artemisiifolia. We conclude that A. artemisiifolia has higher irradiance plasticity in traits pertaining to biomass partitioning, growth and plant structure. It also exhibits greater ability to adjust photosynthetic capacities in response to varying light availability. Moreover, A. artemisiifolia possess a higher capacity for scavenging oxygen radicals at higher irradiance than at lower irradiance. The differential responses of antioxidant enzymes between A. artemisiifolia and U. lobata may be a possible mechanism for differences in irradiance acclimatization between the two species.

MODELLING THE POTENTIAL DISTRIBUTION OF INVASIVE AMBROSIA ARTEMISIIFOLIA IN CHINA. Q. Zhong*, A. DiTommaso, C.L. Mohler, and Z. Jia-en, South China Agricultural University, Guangzhou, Peoples Republic (16)


Ambrosia artemisiifolia L. (common ragweed) an invader with high colonization potential is currently rapidly expanding its range in China where it is considered a serious threat to agricultural production and human health. The ability of A. artemisiifolia to colonize new regions far away from its native North American range has raised considerable concern. Models predicting the potential geographical distribution of A. artemisiifolia can provide valuable insights on the extent of its future spread and information about how different ecological factors may affect its invasion potential. In this study, we used an ecological niche model, maximum entropy (Maxent), based on recorded global occurrence points to identify climatically suitable areas for A. artemisiifolia colonization in China. The models generated by Maxent were imported into GIS with which we performed a spatial analysis to probe the potential occurrence and establishment areas of A. artemisiifolia in China. Estimated latitude and longitude range with high occurrence probabilities of A. artemisiifolia were concentrated between 24.5°~45.5°N, 101.5°~125.5°E, covering the provinces of Jiangxi, Anhui, Hunan, Jiangsu, Zhejiang, Hubei, Liaoning, southern Jilin and northern areas of Guangdong province. Also, most of Sichuan, Heilongjiang and northern Taiwan were suitable establishment areas for A. artemisiifolia. A jackknife test in Maxent indicated that the maximum temperature in November was the most important environmental variable affecting the distribution of A. artemisiifolia in China. Based on these findings, there is a need to develop and implement practical management strategies to prevent further colonization and expansion of A. artemisiifolia in China.



Weed seeds in the soil seed bank may experience different microenvironments depending on the above-ground plant community and therefore may exhibit variation in their emergence response. This hypothesis was investigated in a field experiment that assessed the emergence of seven weed species under a corn canopy. Corn was planted at three densities (8, 12, 16 plant/m2) and two planting patterns (single and double-row). Seeds of seven weed species were sown perpendicular to corn rows at the same time and included, redroot pigweed (Amaranthus retroflexus), green foxtail (Setaria viridis), annual bluegrass (Poa annua), common lambsquarters (Chenopodium album), jimsonweed (Datura stramonium), black nightshade (Solanum nigrum) and Johnsongrass (Sorghum halepense). During the experiment, temperature, and light quality and quantity at the soil surface were measured. The number of emerged seedlings of each weed species was measured at two distance intervals (0-10 cm and 10-20 cm) from the corn rows during three sample periods. Temperature fluctuations at the soil surface did not vary with corn density or planting pattern; but were reduced by the presence of a corn canopy relative to bare ground. We observed three general patterns of seedling emergence for the seven weed species: (1) small-seeded species such as redroot pigweed showed only one emergence flush as the corn canopy closed but emergence was not affected by canopy cover; (2) the number of emerged seedlings of other small-seeded species such as annual bluegrass, common lambsquarters, and green foxtail was significantly higher in bare ground than in the various corn canopy treatments. Moreover, seedling emergence was higher in the corn double-row versus corn single-row planting pattern with species exhibiting three emergence flushes; and (3) for relatively large-seeded species such as jimsonweed and black nightshade, the number of emerged seedlings did not differ significantly between bare ground and the different corn canopy treatments. However, the number of emerged seedlings of Johnsongrass under the corn canopy plots was greater than in the bare ground plots. For all of these three large-seeded weed species, the number of emerged seedlings was higher in double-row corn plantings relative to single-row plantings. Jimsonweed showed three germination flushes; whereas both black nightshade and Johnsongrass produced only one emergence flush. These findings can aid in better predicting the timing and density of seedling emergence flushes of major agronomic weeds in a corn canopy during the growing season. In turn, this information will more effectively guide the proper timing of weed management strategies such as cultivation and herbicide application.

THE EFFECT OF TIMING AND THE METHOD OF CONTROL ON JAPANESE STILTGRASS SEED PRODUCTION. J.L. Huffman*, E.S. Rauschert, A.E. Gover, and A.N. Nord, Penn State, University Park, PA (18)


Japanese stiltgrass, Microstegium vimineum, invades native understory vegetation in a wide range of environments encompassing full sun to full shade. As an annual plant, controlling seed production is critical for management, yet the optimal timing of control and how this is influenced by the control method is not well quantified.  We were specifically interested in assessing whether controlling too early would lead to further germination or regrowth. We tested the effect of timing and method of removal on Japanese stiltgrass seed production. The treatments consisted of string-trimming, hand pulling, and applying glyphosate at a rate of 1.68 kg ae/ha. Treatments were conducted at three different times during the mid/late summer. No subsequent germination was observed, and regrowth was very limited, mainly in the string trimmed and hand pulled controlled plots. At the end of the growing season, stem and seed counts were taken. Glyphosate was the most effective treatment. While mechanical treatments greatly reduced seed production compared to controls, resprouting did lead to some seed production, which could sustain populations for subsequent years. Timing did not affect the efficacy of glyphosate, but it appears that early mechanical control leads to more seed production than later mechanical control. These results suggest that it is most effective to control Japanese stiltgrass chemically at any time mid/late summer or mechanically in late summer, prior to the formation of viable seeds.



Weed control in Northeastern soybeans improved dramatically in the late 1990’s with the introduction of Roundup Ready® soybeans.  A multitude of herbicide mixtures was replaced by one or two in-crop applications of glyphosate.  This both improved crop safety and overall weed control.  However, a few years after the introduction of Roundup Ready soybeans, populations of glyphosate resistant marestail (Conyza canadensis) began to appear.   As time has progressed, concerns have mounted about the development of other glyphosate resistant weeds.  These concerns emphasize the need to modify the weed control programs used in Roundup Ready® soybeans.  In the short term, weed control programs in soybeans must be diversified to include other non-glyphosate herbicides.  Longer term, the development of other herbicide tolerant traits stacked with the Roundup Ready trait will provide growers with additional herbicide tools for managing weeds.  Monsanto is developing dicamba tolerance in soybeans (DTS) to stack with Roundup Ready 2 Yield® soybeans to provide more herbicide options for growers.

           In 2011, multiple trials were conducted on the Delmarva Peninsula examining potential weed control systems in soybeans stacked with glyphosate and dicamba tolerance.  These trials showed that the inclusion of dicamba as a component of a burndown herbicide treatment could result in significant residual weed control.  It was also shown that if dicamba is applied in-crop, applications to smaller weeds are most effective.



Sweet vernalgrass is a perennial grass weed found in cool-season turfgrass that has recently become a concern in Virginia.  It is highly competitive in the spring due to its rapid growth, early flowering, and potential allelopathic suppression.  Research has shown that sweet vernalgrass has high phenotypic plasticity, allowing it to easily adapt to new environmental conditions.  Experiments were conducted near Richmond, Virginia in 2010 and 2011 to determine herbicide options for sweet vernalgrass control in cool-season turf.  Seven herbicide treatments were evaluated.  In 2010, treatments were initially applied on June 15th, with a subsequent mesotrione application applied on July 6th.   At 34 DAT, MSMA at 2.1 kg a.i. ha-1, mesotrione applied once at 0.28 kg a.i. ha-1, and mesotrione applied twice at 0.14 kg a.i. ha-1 controlled sweet vernalgrass 73, 63, and 57%, respectively.  At 71 DAT, control by MSMA declined to 40%, whereas mesotrione applied once and mesotrione applied twice controlled sweet vernalgrass 100 and 67%, respectively.  In 2011, initial treatments were applied April 20th, with a subsequent application of mesotrione applied on May 11th.  Mesotrione applied once and mesotrione applied twice were the only herbicides that controlled sweet vernalgrass.  However, mesotrione applied once did not maintain control and at 71 DAT, control was 0%.  For mesotrione applied twice, control was 100% at 71 DAT.  Fenoxaprop, quinclorac, amicarbazone, methiozolin, and sulfentrazone did not control sweet vernalgrass. In 2010, the decline of MSMA control can likely be explained by MSMA’s contact activity and the perennial nature of sweet vernalgrass.  The differences seen with mesotrione applications between 2010 and 2011 may be explained by application timing. In 2010, rapid growth of sweet vernalgrass in the spring might explain why mesotrione applied once provided the best control as this herbicide tends to be more effective during rapid growth phases of susceptible plants and applying more active ingredient during sweet vernalgrass peak growth may play an important role in its control.  In 2011, however, mesotrione was applied almost two months earlier.  A single application may have been too early in the growing season, allowing the weed to recover.   Additional research will be conducted on application timing of mesotrione to sweet vernalgrass.  Delaying application may result in sufficient control without the need for an additional application.                 

WEED MANAGEMENT WITH TEMBOTRIONE AND ISOXAFLUTOLE IN NORTH CAROLINA. W.J. Everman*, J. Hinton, and M. Rosemond, North Carolina State University, Raleigh, NC (21)


Palmer amaranth has become a driving force in weed management decisions in North Carolina due to widespread glyphosate and ALS-inhibitor resistance in the state. Growers are continually looking for options in primary crops as well as rotation options that allow for greater control. Recently tembotrione was introduced for weed management in corn in North Carolina; however, isoxaflutole currently is not labeled for use in North Carolina. Therefore, studies were initiated to investigate the effectiveness of tembotrione and isoxaflutole on various weeds and soils in North Carolina. Trials were conducted at the Central Crops Research Station near Clayton, NC, the Upper Coastal Plains Research Station near Rocky Mount, NC, and at the Tidewater Research Station near Plymouth, NC to provide a wide range of environmental conditions, weed species, and corn yield potential. Weed control varied by location with generally greater control eight weeks after planting on the sandier soils at Clayton and reduced  control at the other locations. Large seeded broadleaf weeds such as morningglory species and large crabgrass had the lowest control ratings at eight to ten weeks after planting.

INVESTIGATING POKEWEED MANAGEMENT IN FIELD CROPS. K.M. Patches* and W.S. Curran, Penn State, University Park, PA (22)


Common pokeweed (Phytolacca americana L.) is a perennial broadleaf weed with a large persistent taproot that is also capable of abundant seed production. It has become a frequent problem in agronomic crops in Pennsylvania. Traditionally, plowing was used to manage pokeweed; however, the wide-spread adoption of conservation tillage and a decline in the use of soil residual herbicides in soybean may have allowed pokeweed populations to increase in recent years.

Our objective is to identify opportunities to better manage pokeweed in corn, soybeans, and other Northeast cropping systems. We believe an integrated approach that includes both cultural and chemical tactics could be successful in conservation tillage systems. We propose to conduct a number of experiments during the next two years that investigate the biology and control of common pokeweed in Pennsylvania. Plant biology experiments will examine emergence periodicity, seed longevity, and plant growth and fecundity. Herbicide experiments will be conducted in both corn and soybeans.

In 2011, a preliminary experiment was conducted in no-till corn at the Russell Larson Research and Education Center near State College, Pennsylvania, to evaluate herbicide effectiveness on common pokeweed. Seven POST treatments were evaluated which included: glyphosate (0.84 and 1.22 kg ae/ha), dicamba + diflufenzopyr at two rates (0.19 and 0.39 kg ae/ha), glyphosate plus dicamba + diflufenzopyr (0.84 kg/ha + 0.19 kg/ha), glyphosate plus mesotrione (0.84 kg/ha + 0.10 kg ai/ha), and glyphosate plus halosulfuron + dicamba (0.84 kg/ha + 0.18 kg ai/ha). Appropriate adjuvants were included in all treatments. The herbicides were applied on June 17 when the common pokeweed ranged from seedling to established vegetative plant and averaged 89 cm tall. The experiment was replicated three times and the treatments were visually evaluated on July 7 and September 27 on a scale from 0 to 100% control. On August 12, three common pokeweed plants from each plot were harvested and both fresh and dry weights were measured. Untreated plants from outside the plots were also collected for comparison. Preliminary results showed that the high rate of glyphosate provided about 80% control, reducing plant biomass by about 95%. The lower glyphosate rate provided 55% control but still reduced biomass by 91%. Including mesotrione with glyphosate enhanced performance, increasing control to 79% and reducing the biomass by 92%. Other treatments ranged from 36 to 79% control and reduced biomass 48 to 92%. Treatments will be assessed next year for longer-term control and additional trials will further explore both corn and soybean herbicides for common pokeweed control.

MECHANICAL AND CULTURAL EFFECTS ON LIMA BEAN WEED CONTROL. B.A. Scott*, M.J. VanGessel, and Q. Johnson, University of Delaware, Georgetown, DE (23)


Weed control in lima bean has become more complex in recent years in the Mid-Atlantic region due to an increase of Group 2 resistant pigweed (Amaranthus) species.  Growers have relied heavily upon imazathapyr for broadleaf weed control, and with limited options with different modes of action, growers need to implement additional integrated weed management strategies.

Two trials were conducted in 2010 and 2011 in order to determine if lima bean weed densities would be affected by 1) various cultivation equipment and timing of cultivation and 2) cultural production methods, particularly crop preceding lima bean and respective planting date.  Each trial was a randomized complete block design with four replications.

Treatments in the lima bean cultivation trial were a factorial arrangement of cultivator and cultivation timing.  The two cultivators were a standard s-tine cultivator and an in-row cultivator (BezzeridesTM).  Cultivation was initiated at lima bean unifoliate stage, first trifoliate, second trifoliate, or rotary hoe at five days after planting (DAP) with cultivation at the unifoliate stage.  All treatments with cultivation were cultivated twice, first time as noted followed by cultivation 7 days later.  Comparison treatments include standard cultivator at unifoliate followed by 0.75 lbs ai/A of bentazon seven days later, 0.75 lbs ai/A of bentazon at the first trifoliate followed by standard cultivation seven days later, and an untreated check.  Trial area had a residual herbicide application at planting.

Treatments in the lima bean rotation trial were: early-season lima bean following peas; early-season lima bean with no preceding crop; mid-season lima bean planted after barley harvest; mid-season lima bean into no-till bare ground; late-season lima bean after sweet corn which had no cultivations; and late-season lima bean planted after sweet corn which had two cultivations.   All treatments were planted following soil preparation with heavy disking and/or field cultivation, with the exception of the one no-till treatment.  Each lima bean planting received a PRE treatment of 1 lb ai/A of s-metolachlor.

Weed counts over a 25 ft2 area were completed at lima bean flower and at harvest.  All plots were harvested and yields recorded.

In the lima bean cultivation trial pigweed density was lower when cultivation was delayed until the second trifoliate stage of the lima bean.  There were no differences detected in weed densities between the in-row and standard cultivators.  Pigweed densities were similar with or without the rotary hoeing followed by cultivation at the unifoliate stage. 

Lima bean rotation influenced pigweed and morningglory densities.  Pigweed and morningglory densites were less in late-planted lima bean.  Also, yield by treatment interactions were observed.  Yields differed by preceding crop as well as planting date.

THE WEEDOLYMPICS: A NATIONAL WEED SCIENCE CONTEST. J.T. Brosnan*, G. Armel, G.K. Breeden, J.J. Vargas, and M.J. VanGessel, University of Tennessee, Knoxville, TN (24)


The WeedOlympics was the first national weed science contest involving student members of the Northeastern Weed Science Society (NEWSS), the North Central Weed Science Society (NCWSS), the Southern Weed Science Society (SWSS), and the Western Society of Weed Science (WSWS). A total of 137 graduate and undergraduate students from across the United States and Canada participated in this event hosted at the University of Tennessee (Knoxville, TN) in 2011. A total of 56 NEWSS students participated in the WeedOlympics. Universities represented included North Carolina State University, the University of Guelph, Cornell University, Virginia Polytechnic Institute and State University (Virginia Tech), and the Pennsylvania State University. At the regional level, University of Guelph Team #4 (Thomas Judd, Adam Parker, Michael Vanhie, and Jessica Gal) took top honors in the undergraduate competition. This team also placed first in the overall national undergraduate team competition. A team from North Carolina State University (Dustin Lewis, Stephen Meyers, and Bill Foote) placed first in the graduate competition at the regional level. The top graduate team at the national level was from Purdue University (Jared Roskamp, Ryan Terry, Chad Barbham, and Paul Marquardt). The top undergraduate and graduate individuals at the regional level were Dan Tekiela (Virignia Tech) and Dustin Lewis (North Carolina State). Dan Tekiela was also the overall national winner in the individual undergraduate competition. The overall national winner in the graduate competition was Jason Parrish from The Ohio State University.   Distinguished NEWSS member, Dr. Gary Schnappinger, spoke at the awards banquet on the history of the NEWSS student contest and presented NEWSS students with their awards along with current NEWSS president, Dr. Mark VanGessel.  Thank you to all the students, coaches, and volunteers who made the WeedOlympics a great event.




Metamifop is a new herbicide under development in US markets by Summit Agro.  Metamifop controls annual grasses without injuring desirable cool season turfgrass species.  Already marketed in 9 other Asian and 6 Middle Eastern countries as a postemergent annual grass herbicide in cereal crops and rice, metamifop shows great potential for future expansion to Japan and North America.  Metamifop inhibits acetyl-CoA carboxylase (ACCase) which is the enzyme that catalyzes the first step in fatty acid synthesis.  This enzyme inhibition prevents production of phospholipids which are the building blocks for new membranes and cell growth.  Cool-season turfgrasses are said to gain tolerance to metamifop via an altered ACCase binding site, which makes this herbicide unique among other ACCase inhibitors that rely on rapid metabolism for turf safety.  Field trials conducted in Blacksburg, VA evaluated the use of metamifop in application intervals and metamifop in conjunction with the broadleaf herbicides 2,4-D + dicamba + MCPP (Trimec Classic, PBI Gordon Corporation), carfentrazone (Quicksilver, FMC Corporation), and mesotrione (Tenacity, Syngenta) for control of smooth crabgrass (Digitaria ischaemum).  The experiments were implemented in Kentucky bluegrass (Poa pratensis) and perennial ryegrass (Lolium perenne) maintained at fairway height.  Treatments for the metamifop interval trial consisted of metamifop applied at 300 g ai/ha alone or followed by an additional application at 3, 6, or 8 weeks after initial application.  Treatments for the metamifop/broadleaf herbicides combination trial consisted of metamifop applied at 300 g ai/ha alone, Trimec Classic alone at 4.68 L/ha, Quicksilver alone at 0.15 L/ha, Tenacity alone at 0.58 L/ha, metamifop + Trimec (same rates as single treatments), metamifop + Quicksilver, and metamifop + Tenacity.  A nontreated check was included in all trials for comparison.  When applied alone at 3, 6, or 8 week intervals, metamifop controlled smooth crabgrass 88 to 98% and significantly better than metamifop applied once.  These treatments did not injure Kentucky bluegrass or perennial ryegrass at any time during the study.  Applications of metamifop alone, metamifop + Quicksilver, and metamifop + Tenacity controlled smooth crabgrass 65-90% initially and 55-63% 12 weeks after treatment (WAT).  Metamifop + Trimec only controlled crabgrass 10% initially and 6% 12 WAT, suggesting a possible antagonism between the two herbicides.  Likewise, Trimec alone controlled dandelion (Taraxacum officinale) 90% 12 WAT and significantly better than metamifop + Trimec at 57% control 12 WAT.  Nevertheless, metamifop + Trimec controlled white clover (Trifolium repens) 97% 12 WAT and significantly better than all other treatments.  According to these data, metamifop is an effective herbicide for controlling smooth crabgrass in cool season turfgrasses when applied twice at 3, 6, or 8 week intervals.  In addition, although metamifop may have safety when added to some broadleaf herbicides, an antagonistic response resulted when it was combined with Trimec Classic as a crabgrass/broadleaf herbicide tank mix.  2,4-D and MCPP, two active ingredients in Trimec Classic, are also known antagonist of other ACCase inhibiting herbicides such as fenoxaprop.


TALL FESCUE TOLERANCE TO TOWER (DIMETHENAMID) AND FREEHAND (DIMETHENAMID + PENDIMETHALIN). D... Gomez de Barreda* and P. McCullough, Polytechnic University of Valencia, Valencia, Spain (26)


Freehand (1.75G) contains dimethenamid (0.75%) and pendimethalin at (1%) and is being evaluated for potential use as a preemergence herbicide in turf.  The objective of this field experiment was to investigate tolerance of a ‘Talladega’ tall fescue field established in fall 2010 to spring applications of Freehand in 2011.  Treatments included Freehand at 0, 2.94, 3.92, 5.9, and 7.85 kg a.i./ha, Tower 6L (dimethenamid) at 1.68 and 3.36 kg a.i./ha, and Pendulum 3.8ME (pendimethalin) at 2.24 kg a.i./ha.  All treatments were applied May 16 and again on June 28, 2011. Freehand injured tall fescue 11 to 34% by 6 weeks after initial treatments (WAIT) while all other treatments caused ≤15% injury.  After the second application, tall fescue injury from Freehand ranged 19 to 50% by 10 WAIT but sequential applications of Pendulum and Tower caused <10% injury. Freehand rates >2.94 kg a.i./ha reduced turf quality on several dates from the untreated but Tower and Pendulum applied separately did not reduce quality.  


#27. D. Lycan*, Syngenta, Baldwinsville, NY (27)


#28. D. Lycan*, Syngenta, Baldwinsville, NY (36)


#29. D. Lycan*, Syngenta, Baldwinsville, NY (35)


#30. D. Lycan*, Syngenta, Baldwinsville, NY (34)


#31. D. Lycan*, Syngenta, Baldwinsville, NY (33)


#32. D. Lycan*, Syngenta, Baldwinsville, NY (32)


#33. D. Lycan*, Syngenta, Baldwinsville, NY (31)


#34. D. Lycan*, Syngenta, Baldwinsville, NY (30)


#35. D. Lycan*, Syngenta, Baldwinsville, NY (29)


#36. D. Lycan*, Syngenta, Baldwinsville, NY (28)


#37. D. Lycan*, Syngenta, Baldwinsville, NY (37)




     The commercial release of the herbicide saflufenacil (trade name Sharpen) in 2010 has provided a new tool to help farmers manage the growing population of glyphosate-resistant horseweed (Conyza canadensis L.).    The original labels for Sharpen and the prepackaged mix of saflufenacil + imazethapyr (trade name Op-Till) restricted applications to 30 days preplant (DPP) for soybeans [Glycine max (L.) Merr ] planted on coarse-type soils with less than 2% organic matter.  In 2011, a supplemental label allowed up to 1.5 oz/acre of saflufenacil on coarse-type soils with a 44 day interval from application to planting.  Much of the farmland on the Delmarva Peninsula is categorized as coarse or coarse-type soils.  Up to 50% of horseweed plants in Maryland do not germinate until the spring, leaving growers with a small window between using a burndown herbicide application and planting their soybean crop.  Sensitive and non-sensitive soybean varieties have been identified when saflufenacil is applied within 30 DPP on coarse-type soils.

     Field studies were conducted in the summers of 2010 and 2011 at the Wye Research and Education Center (WREC) located in Queenstown, MD, and the Central Maryland Research and Education Center (CMREC) located in Beltsville, MD, on the effect of saflufenacil preplant application timing on full-season no-till soybeans.  The WREC site was selected for its medium-type soils, while the CMREC site was selected for its coarse-type soils.  Studies included one saflufenacil-susceptible soybean variety, and one saflufenacil-tolerant soybean variety at each location.  Treatment combinations consisted of the following:  glyphosate at 0.95 lb ai/A, saflufenacil at 0.022 lb ai/A + glyphosate at 0.95 lb ai/A, saflufenacil at 0.045 lb ai/A + glyphosate at 0.95 lb ai/A, and Op-Till at 0.085 lb ai/A + glyphosate at 0.95 lb ai/A.  Ammonium sulfate and a methylated seed oil were added to all saflufenacil containing treatments.  These treatments were repeated at 0, 15, and 30 DPP on separate plots.  All treatments received a subsequent postemergence application of glyphosate at 0.95 lb ai/A. Stand counts and height measurements were taken at 4, 7, and 10 weeks after planting (WAP).  In 2010, crop injury and reduced yields were observed for the treatments containing saflufenacil at 0.045 lb ai/A at 0 and 15 DPP, as well as the treatment containing saflufenacil at 0.022 lb ai/A at 0 DPP in the sensitive soybean variety at CMREC.  No significant differences were noted in the other studies.

     Greenhouse studies were conducted in 2011 on the efficacy of saflufenacil on both glyphosate-resistant and glyphosate-susceptible horseweed.  Treatment combinations consisted of the following: glyphosate at 0.95 lb ai/A, saflufenacil at 0.022 lb ai/A, saflufenacil at 0.022 lb ai/A + glyphosate at 0.95 lb ai/A, and Op-Till at 0.085 lb ai/A.  As in the field studies, ammonium sulfate and a methylated seed oil were added to all saflufenacil containing treatments.  Treatments were applied to horseweed rosettes that were 0.5, 2.0, and 3.5 inches tall for both biotypes.  Visual assessments were made on treatment efficacy at 1, 2, and 4 weeks after treatment (WAT).  At 4 WAT, fresh and dry weights of the plants were taken.  The combination of glyphosate + saflufenacil provided significantly better control than other treatments for the resistant-biotype.  Both the glyphosate and the glyphosate + saflufenacil treatments provided the most effective control for the susceptible-biotype.



Greenhouse and laboratory trials were conducted using 14C-aminocyclopyrachlor to evaluate root and foliar absorption, translocation, and metabolism in loblolly pine (Pinus taeda). Pine seedling plugs were used for all experiments. Trees designated for foliar experiments were first treated with formulated aminocyclopyrachlor in an overhead track sprayer before applying radiolabeled aminocyclopyrachlor to a single needle. Trees for root absorption studies were grown in half strength Hogland’s solution spiked with 14C-aminocyclopyrachlor. Plants were harvested at 1, 2, 4, 8, 24, and 48 hours after treatment (HAT) for all experiments. Plants with foliar treatments were harvested and divided into roots, lower stem, upper stem, bud, treated needle with fascicle, and untreated needle(s). Plants treated by root application were harvested and divided into roots, lower stem, upper stem, and bud. All partitioned plant parts were stored in envelopes at -20C. To determine absorption and translocation designated plant parts were dried, homogenized and radiation was quantified using liquid spectroscopy after being combusted in a biological oxidizer. Aminocyclopyrachlor metabolism was determined only in the treated needle and fascicle. The tissue was extracted in 90% methanol, and evidence of metabolism was determined using High Performance Liquid Chromatography. The results demonstrated that a maximum of 37% of the aminocyclopyrachlor (free acid) was absorbed after foliar application. Absorption was rapid, with the maximum by one hour. No significant difference was found in translocation regardless of harvest interval; 59% of the free acid remained within the treated needle and fascicle, 27% in the upper stem section, and all other parts had significantly less aminocyclopyrachlor with a range of 0.5 to 9%. Root absorption occurred in a linear fashion at a rate of one percent per hour and showed great xylem mobility after 48 HAT. Lastly, no metabolism of the aminocyclopyrachlor free acid was seen between 1 and 48 HAT when foliar applied.



            Annual bluegrass (Poa annua L.; ABG) is one of the most widely distributed turfgrass species in the world and is generally considered a weed on golf course putting greens. Variation in ABG populations exists and is dependent upon a large number of factors. Due to this natural variation, control of the various biotypes can be highly variable. The objective of this study was to investigate the tolerance of perennial ABG biotypes to methiozolin, amicarbazone and bispyribac-sodium.  Greenhouse studies were conducted in 2011.  A total of 30 ABG biotypes were seeded at a rate of 98 kg seed/ha into pots measuring 79.2 cm2 on 3 May and 16 September. Pots were arranged in a randomized complete block design with five replications.  Prior to treatment, ABG was fertilized and treated with fungicides to prevent diseases. Herbicide treatments included amicarbazone (0.147 kg a.i./ha), bispyribac-sodium (0.074 kg a.i./ha), methiozolin (2.0 kg a.i/ha), and an untreated control.  All treatments were applied twice on a 14-day interval in 815 L H20/ha using a CO2 backpack sprayer (276 kPa). The ABG pots treated with amicarbazone were severely injured within 1 week of initial application. Turfgrass treated with bispyribac-sodium or methiozolin resulted in a less rapid decline when compared to amicarbazone. In general, all 30 ABG biotypes were killed within 3 and 6 weeks when treated with amicarbazone and methiozolin, respectively. At the conclusion of the study, control of ABG was highly variable in pots treated with bispyribac-sodium.  Based on the initial trial, amicarbazone and methiozolin provided complete control of all 30 ABG biotypes evaluated in this study. Amicarbazone appears to be most useful in situations of minimal ABG population and/or where a rapid kill is desired. Methiozolin provided a slower suppression of ABG and may be useful in situations where high populations are present or limited disruption to the putting surface is desired. The study is current being repeated and results of the completed study will be discussed.

HERBICIDAL ACTIVITY OF HETEROCYCLIC ANALOGUES OF DICHLOBENIL ON VARIOUS WEED AND ORNAMENTAL SPECIES. J.W. Thomas*, G. Armel, M.D. Best, W. Klingeman, C. Do-Thanh, and H.E. Bostic, University of Tennessee, Knoxville, TN (41)


Discovery of novel chemistries which target herbicide sites of action that have little to no weed resistance issues is imperative for the future management of resistant weed biotypes. The herbicide dichlobenil (2,6-dichlorobenzonitrile) is an inhibitor of cellulose biosynthesis that is implemented for preemergence (PRE) control of various grass, broadleaf, and sedge weeds in orchards, ornamental nurseries, and various non-crop systems. To date there is only one weed biotype that is resistant to an inhibitor of cellulose biosynthesis. Greenhouse and laboratory studies were conducted at the University of Tennessee to evaluate various nitrogen containing heterocyclic analogues of dichlobenil for PRE weed control in ornamental containers, while maintaining crop safety to forsythia (Forsythia x intermedia “Lynnwood Gold”) and Japanese Holly (Ilex Cronata (“Noble Upright”). This paper will discuss the changes in herbicidal response with those novel analogues for weed management in ornamental production.

EVALUATION OF AMINOCYCLOPYRACHLOR FOR CONTROL OF INVASIVE PLANT SPECIES IN TENNESSEE. J.J. Vargas*, G. Armel, W. Klingeman, P. Flanagan, R.M. Evans, R.J. Richardson, and R.L. Roten, University of Tennessee, Knoxville, TN (42)


The cost of managing invasive plant species annually in the United States is estimated to be $35 billion dollars (Pimentel et al. 2004).  According to the Center for Invasive Species and Ecosystems Health, there are 388 invasive plant species in the state of Tennessee and these species are categorized as aquatic plants, forbs or herbs, grasses, hardwood trees, shrubs and vines.  The University of Tennessee has established multiple studies from 2009 to 2011 to evaluate how the auxin mimic herbicide aminocyclopyrachlor controls key invasive species.   Field and greenhouse studies were conducted to evaluate aminocyclopyrachlor alone and in mixtures for control of species like sericea lespedeza (Sericea lespedeza), kudzu (Pueraria montana), and Chinese privet (Ligustrum sinense).  Treatments included aminocyclopyrachlor applied at 16 to 263 g ai/ha alone or in mixtures with metsulfuron at 21 to 82 g ai/ha, 2,4-D at 1080 g ai/ha, imazapyr at 177 to 3730 g ai/ha, glyphosate at 1512 to 2030 g ai/ha, indaziflam at 70 g ai/ha, hexazinone at 2240 g ai/ha and/or fosamine at 6730 g ai/ha.  Additional industry standard treatments included aminopyralid applied at 123 g ai/ha and triclopyr at 5050 g ai/ha.  All treatments were applied POST and included 1% v/v of methylated seed oil or 0.5 to 1% v/v of non ionic surfactant.  All mixtures containing aminocyclopyrachlor provided 100% control of lespedeza by 120 days after treatment (DAT).  Aminocyclopyrachlor applied at 66 g ai/ha plus metsulfuron at 21 g ai/ha plus 2,4-D at 1080 g ai/ha provided 96% control of kudzu by one year after treatment (YAT).  The addition of metsulfuron to the mixture of aminocyclopyrachlor plus 2,4-D was more effective in the control of kudzu than that observed by aminocyclopyrachlor plus 2,4-D.  In the greenhouse, aminocyclopyrachlor applied at 66 g ai/ha plus 2,4-D at 1080 g ai/ha provided 53% visual control and 63% biomass reduction of Chinese privet.  In the field, aminocyclopyrachlor at 263 g ai/ha plus metsulfuron at 84 g ai/ha provided 99% control of Chinese privet by 1 YAT when applied as a foliar broadcast application and was significantly more effective than responses observed with aminocyclopyrachlor applied alone at 263 g ai/ha.  These observations indicate that mixtures of aminocyclopyrachlor plus the addition of other auxin mimic herbicides and/or active ingredients that affect acetolactate synthase greatly increase the control of invasive species over that provided by any products applied alone.

FINE FESCUE VARIETAL TOLERANCE TO GLYPHOSATE RATES. M.C. Cox*, S. Askew, W. Askew, and J. Goatley Jr., Virginia Tech, Blacksburg, VA (43)


As the current economic turn down affects golf budgets, more scrutiny is placed on managed turf areas to reduce fertility and mowing costs.  Nonmow areas, or secondary roughs, are a cost effective and visually appealing approach to maintaining out-of-play areas on the golf course.  Fine fescues are typically used for these areas because they are shorter than other grasses and tend to allow golfers to find and advance errant shots.  A unique set of weeds exist in nonmow situations and weed control programs are lacking.  Some fine fescues have demonstrated tolerance to glyphosate in past research, and glyphosate would be a valuable tool for controlling various perennial grass weeds in nonmow areas.  More information is needed to determine which fine fescue varieties are more tolerant to glyphosate and how glyphosate rates affect visual quality and seedhead production of fine fescues.  The objective of this study was to evaluate glyphosate at 0.6, 0.8, and 1.4 kg ai/ha for effects on visual quality, NDVI, and seedhead production of 56 fine fescue varieties. 

Glyphosate was applied at 0.6, 0.8, and 1.4 kg ai/ha with an 18 inch wide sprayer on May 16, 2011.  The 56 fine fescue varieties were comprised of 1 sheep fescue, 3 slender creeping fescues, 12 hard fescues, 13 chewings fescues, and 27 strong creeping fescues.  All plots were mowed in April approximately 5 weeks prior to treatment and not mowed again for the duration of the study.  Glyphosate injured fine fescue most at 1 month after treatment.  At this timing, 22, 9, and 2 varieties maintained acceptable quality when treated with 0.6, 0.8, and 1.4 kg ai/ha glyphosate, respectively.  Of the 22 varieties that maintained acceptable quality 1 month after 0.6 kg ai/ha glyphosate, 12 were hard fescues, 8 were strong creeping, 1 was a slender creeping, and 1 was a sheep fescue.  The following 7 hard fescue and 1 sheep fescue varieties maintained acceptable quality 1 month after 0.8 kg ai/ha glyphosate: SPM, Pick HF#2, Berkshire, Quatro, IS-FL 28, Scaldis, SRX 3K, Oxford, and Heron.  Only Quatro sheep fescue and Oxford hard fescue maintained acceptable quality 1 month after glyphosate at 1.4 kg ai/ha.  When not treated with glyphosate, the following 9 hard fescues and 5 strong creeping fine fescue varieties had seedheads on 25% of plots or less:  Predator, SPM, A0163Rel, C-SMX, Pick HF#2, Berkshire, DLF-RCM, IS-FRR30, IS-FL 28, SR 3000, Oxford, DP 77-9360, DP 77-9579, and Heron.  When not treated with glyphosate, the following 12 chewings fescues, 2 strong creeping fescues, and 1 slender creeping fescue had seedheads on 70% or more of plot area:  7 Seas, ACF 174, Jamestown 5, ACF 188, LongFellow II, IS-FRC17, BUR 4601, SRX 51G, SRX 55R, Ambassador, DP 77-9885, DP 77-9886, PST-4TZ, Musica, and Navigator.  When treated with 0.6 kg ai/ha glyphosate, seedhead coverage was less than 6% regardless of variety and seedheads were not produced by any variety when treated with the two higher glyphosate rates.  These data suggest chewings fescues produce the most seedheads while hard fescues and sheep fescues have better glyphosate tolerance.



Indaziflam is a cellulose biosynthesis inhibitor used for annual grassy weed control in warm-season turfgrass. Bermudagrass (Cynodon spp.) injury following indaziflam treatment has been observed by turfgrass managers. Research was initiated in 2011 to determine the effect of rooting depth on bermudagrass injury with indaziflam in various soils.

Hybrid bermudagrass (C. dactylon x. C. transvaalensis Burtt-Davey, cv. Tifway) was established from washed sod in mini-rhizotrons at the University of Tennessee in August 2011. Silica sand and silt loam soil were poured and packed into each mini-rhizotron at a density of 1.6 Mg m-3. An overhead irrigation system was used to promote active growth. Plants were maintained at a height of 3.8 cm and were fertilized weekly at 49 kg N ha-1 with a complete fertilizer (20N: 20P2O5: 20K2O).

The experiment was arranged in a 2 x 3 x 6 factorial, randomized complete block, design with four replications. Plants established in each soil were treated with six herbicides once root growth had reached three depth thresholds (5, 10, and 15 cm). Herbicide treatments included indaziflam (35, 52.5, and 70 g ha-1), prodiamine (595 and 840 g ha-1) and oxadiazon (3360 g ha-1). An untreated control was included for comparison. Treatments were applied with a CO2-powered boom sprayer calibrated to deliver 281 L ha-1 utilizing flat-fan, 8002 nozzles at 124 kPa. Treatments were watered in (~6 mm) after application.

Bermudagrass injury was visually evaluated weekly after application using a 0 (no injury) to 100 (complete kill) scale. Digital image analysis was also performed to support visual assessments of injury. At 6 weeks after treatment (WAT) roots were washed free of debris and excised as close to the crown as possible. WinRhizo software was used to characterize root length, root length density, and root surface area. Leaf tissues were also analyzed for macro- and micronutrient content.

Significant soil-by-rooting depth and soil-by-treatment interactions were detected in visual injury by 5 WAT. In sand, treatments initiated at the 5 cm rooting depth injured bermudagrass 26% compared to 9% injury for treatments initiated at 10 and 15 cm. In silt loam, bermudagrass injury measured <1% at all rooting depths. When applied to bermudagrass established in sand, injury with indaziflam ranged from 24 to 41% at 5 WAT. When applied to bermudagrass established in silt loam, no indaziflam treatment resulted in significant injury compared to the untreated control. Regardless of soil, neither prodiamine and nor oxadiazon resulted in significant bermudagrass injury in this study at 5 WAT. Compared to the untreated control, all parameters of root architecture were reduced following herbicide treatment regardless of soil type or herbicide. Reductions with indaziflam on sand ranged from 81 to 90% but only 41 to 59% on silt loam. Similarly, reductions with prodiamine ranged from 68 to 70% on sand but only 17 to 37% on silt loam.

EFFECT OF CORN HERBICIDES ON SUCCESSFUL COVER CROP ESTABLISHMENT. C.S. Dillon* and W.S. Curran, Penn State University, university park, PA (45)


Cover crops are becoming an integral part of agricultural production systems due to the many benefits that they provide to the crop, soil, and environment.  These benefits include the cover crops ability to scavenge and/or fix nitrogen, improve soil structure and add organic matter, reduce erosion and transport of nutrients into waterways as well as potentially providing a forage source for livestock.  Despite these numerous benefits, many farmers are still not including cover crops in their rotation. There are several important reasons for this including the added cost associated with cover crop seed and the extra trips across the field for establishment.  In addition, the late fall timing of corn or soybean grain harvest can limit timely cover crop establishment.  Finally, producers using soil residual herbicides in corn and soybean may limit cover crop options due to concerns for subsequent herbicide injury.

Studies were conducted at the Russell Larson Research and Education Center near State College, Pennsylvania to study opportunities for inter-seeding cover crops in corn and to  evaluate the effects of corn herbicides on subsequent cover crop establishment. The studies were conducted in 2010 and are continuing in 2011.  The inter-seeding study evaluated a prototype cover crops seeder that inter-seeds cover crops in no-tillage corn at the V6 to V8 growth stages.  Cover crops included red clover (Trifolium repens L.), white clover (Trifolium repens L), annual ryegrass (Lolium multiflorum Lam.), and a red clover-ryegrass mix. The study was conducted at two locations with the first in corn following corn and the second in corn following soybean.  Corn grain yield was quantified for each treatment and cover crop dry matter was collected following corn harvest and in the following spring.  The herbicide experiment examined the effect of PRE and POST corn herbicides for successful cover crop establishment with the inter-seeder or after corn silage.  Some small grains and winter annual legumes were included in the fall evaluation.  Cover crops were visually evaluated for percent stand.

First year results showed that inter-seeded cover crops did not impact corn yield.  Corn planted into corn residue averaged about140 bu/acre, while yields averaged 170 bu/acre following soybean.  Cover crop dry matter yields ranged from 100 to 500 lb/acre in late fall and 200 to 1450 lb/acre in the spring.  Annual ryegrass and annual ryegrass plus red clover yields were higher than for other treatments.  In the herbicide experiment, most herbicides had little effect on the fall seeded species.  With the inter-seeding, metolachlor, atrazine, pendimethalin, and post-applied nicosulfuron reduced annual ryegrass establishment, whileclover establishment varied across the experiment. These studies continue in 2011 and results will hopefully help farmers make better decisions about cover crop selection, time of seeding, and herbicide management.   

PARTITIONING OUT THE EFFECTS OF NUTRIENTS FROM COMPOSTED MANURE ON WEEDS AND CROPS. N.G. Little*, C.L. Mohler, A. DiTommaso, and Q.M. Ketterings, Cornell University, Ithaca, NY (46)


            Most experienced organic farmers consider weeds to be the worst pest problem they face. This problem can be exacerbated by fertility management that does not take weed ecology into account. Increased weed growth and competition is observed in response to many inorganic fertilizers. The purpose of this research project is to partition out the effects on weeds and crops of nitrogen (N), phosphorous (P), and potassium (K) from organic nutrient amendments. The long-term goal of this project is to contribute to integrated weed and fertility management by providing growers with information that will help them supply crops with necessary nutrients while minimizing weed pressure.

            Field and greenhouse experiments were carried out over two years, using blood meal for an organic source of N, bone char for P, and potassium sulfate for K.  Three crops were studied: field corn (Zea mays cv. ‘VK6710’), lettuce (Lactuca sativa cv. ‘New Red Fire’), and kale (Brassica oleracea cultivar ‘Lacinato’).  Four weeds were studied: Powell amaranth (Amaranthus powellii S. Wats.), common lambsquarters (Chenopodium album L.), giant foxtail (Setaria faberi Herrm.), and velvetleaf (Abutilon theophrasti Medik.). 

            One of the main conclusions of this project is that some weed species, Powell amaranth in particular, benefit from high compost amendments much more than some crops, particularly field corn.  Lettuce may benefit somewhat from high compost amendment levels, but good weed management would be crucial to maintain that benefit since the weeds respond strongly to the compost and are inherently more competitive than lettuce. 

EFFECTS OF SOIL MANAGEMENT LEGACY ON WEED-CROP COMPETITION. H.J. Poffenbarger*, S. Mirsky, J. Teasdale, J. Spargo, D. Timlin, J. Maul, and M. Cavigelli, USDA-ARS, Beltsville, MD (47)


Cropping systems research has shown that organic systems can have comparable yields to conventional systems at higher weed biomass levels. Higher weed tolerance in the organic systems could be due to differences in labile soil organic matter and subsequent nitrogen mineralization potential. The objective of our study was to test whether inherent soil nitrogen (N) mineralization potential differences in organic and conventionally-managed systems within a long-term cropping system experiment result in different weed-crop competition relationships. Greenhouse experiments were first conducted to determine the densities of corn (Zea mays L), smooth pigweed (Amaranthus hybridus L.) and giant foxtail (Setaria faberi L.) that result in equivalent N uptake. Initial experiments tested N use by a range of monoculture densities over a single 41- or 31-day after planting (DAP) timeframe and a subsequent experiment tested a subset of monoculture densities over several timeframes between 21 and 46 DAP. We used leaf area, shoot biomass and shoot N measured in these experiments to determine functional densities. The empirically determined functional densities were then utilized within a replacement series experiment to determine differences in weed-crop competition among the two soil management legacies. The corn:weed mixtures at proportions of 100:0, 75:25, 50:50, 25:75 and 0:100 were planted in three replicates in each soil, with 100% corn equal to 4 plants pot-1 (105 plants m-2) and 100% giant foxtail and smooth pigweed equal to 36 plants pot-1 (947 plants m-2). Species-specific shoot biomass and shoot N content, total root biomass, and soil inorganic N concentration were measured at each of three 24-, 35- and 43-DAP harvests. Total dry weight and N uptake by the species in mixture relative to monoculture were calculated for plants grown in each soil at the three harvests. Determination of functional densities and relationships observed in the competition experiment will be demonstrated.


EVALUATING INTEGRATED WEED MANAGEMENT FOR NO-TILL DAIRY CROPPING SYSTEMS. E.M. Snyder*, W.S. Curran, H.D. Karsten, and G.M. Malcolm, Pennsylvania State University, University Park, PA (48)


Small dairy farms characterize much of the Pennsylvania landscape, many producing the forage and some of the grain consumed by their herd. Rotating annual grain crops with perennial forages is common, and many farmers have adopted no-till practices. Weed populations in conventional no-till crops are managed with herbicides, often involving multiple applications per year. However, interest in reducing herbicide use is increasing as concern grows over environmental consequences of herbicides and the development of herbicide-resistant weeds. While no-till practices offer many benefits, they exclude the use of tillage for weed control. Weed management programs that minimally disturb soil, reduce herbicide use,  rely more on cultural control tactics, and discourage the evolution of herbicide-resistant weeds will help sustain northeast cropping systems into the future.

The Sustainable Dairy Cropping Systems Project, funded by the Northeast Sustainable Agriculture Research and Education (NE-SARE) program, consists of two diverse six-year crop rotations, each containing three years each of annual and perennial crops. The experiment is being conducted at the Russell E. Larson Agricultural Research Station at The Pennsylvania State University near State College, PA, and is modeled after an average-sized 60-cow dairy farm. The “Forage” rotation produces most of the needed forage, and features a comparison of manure management methods. The “Grain” rotation produces corn grain and soybean, as well as forage. It compares an herbicide-based “Standard Herbicide” weed management program with a “Reduced Herbicide” program which includes a combination of mechanical, cultural, and chemical control tactics.  Both rotations also include canola that is utilized as an energy crop.

Applying diverse tactics for weed control can have synergistic effects whereby the efficacy of one tactic is enhanced by use of another. The “Reduced Herbicide” program combines banding herbicide over the crop row, suppressing weed emergence with rolled cover crop mulch, and using a high-residue cultivator to control weeds between the rows in corn and soybean. Planting companion crops is compared with herbicide application for weed control efficacy in establishment-year alfalfa.  Weed density and biomass are quantified to test treatment effectiveness, and crop yields and quality are collected and analyzed for correlation with weed density or biomass. Weed data is collected both from resident populations, and from subplots that have been supplemented with three species of weed seeds.

First year results showed differences in weed density and biomass between weed management programs in both corn and soybean. Weed density and biomass were greater in “Reduced Herbicide” corn grain before, and in both corn and soybean after post-emergence weed management, as compared with “Standard Herbicide” management. There was no difference in corn and soybean grain yield between weed management programs in 2010; 2011 yields are still being collected.  In alfalfa, there were no differences in percent weed composition or forage yield between treatments, and forage quality is currently being analyzed.

THE EFFECT OF ROW SPACING ON WEED PRESSURE, YIELD AND ECONOMICS IN SOYBEAN. J.M. Orlowski*, W.J. Cox, and A. DiTommaso, Cornell University, Ithaca, NY (49)


Soybean production has increased steadily in the United States and New York State in the last 20 years.  As new soybean growers enter production, agronomic factors such as selection of row spacing becomes increasingly important.  Soybeans are currently planted in 19 cm rows using a grain drill or in 38 and 76 cm rows using a row crop planter.  Most studies show that planting soybeans in narrow rows lead to a yield advantage over soybeans planted in wider rows in northern latitudes.  One of the goals of this 2-year field study was to determine the impact of soybean row spacing and weed management program on weed abundance, soybean yield and farm profitability. This research was initiated in 2010 on two collaborator farms in the major soybean production regions of New York.  At both locations, soybeans were seeded at approximate populations of 309,000 and 420,000 plants/ha at three row spacings (19, 38, and 76 cm widths). There were three replicates of each row spacing/seeding rate treatment at each location.  One of the sites was chisel plowed, disc harrowed and received a pre-emergence application of Enlite (premix of flumioxazin, chlorimuron- ethyl and thifensulfuron-methyl at 0.204 liters /ha), which resulted in very low weed densities during both growing seasons.  The other site was planted under no-till conditions in both years.  In 2010 the site received an early pre-plant burndown application of glyphosate 672 g ai/ha, 2-4 D at 512 g ai/ha, and tribenuron at 279 g/ha.  In 2011 due to wet spring conditions a pre-emergence application glyphosate was applied as a burndown two days after planting.  In both years, post emergent applications of glyphosate occurred 4-5 weeks after planting.  Weed densities were determined before post-emergent and at five weeks after post-emergent glyphosate applications in both years in a 2 m sampling area of each treatment combination using a 1 x 0.5 m quadrat.  Dry weed biomass within each row spacing/seeding rate treatment was determined at harvest.  Soybeans planted in narrow rows (19 and 38 cm) had substantially lower weed densities compared to soybeans planted at 76 cm row spacing after herbicide application at both populations at the no-till site.  The narrow row soybeans also had lower weed biomass at harvest compared with the wider row spacing at the no-till site.  Nevertheless, soybean yield did not differ in either year at the no-till site. At the tilled site, soybeans in 19-cm row spacing yielded 3.5% higher than soybeans in 76-cm row spacing.  Planting soybeans in narrow rows led to an increase in net farm profitability because of the yield increase at the tilled site and because of a decrease in the cost of controlling perennial weeds in subsequent rotational crops at the no-till site.         




The integration of cover crops and shallow high-residue cultivation into no-till soybean production will increase cropping system sustainability and reduce selection pressure for herbicide resistant weeds.  Cover crops decrease erosion, improve soil quality and diversify crop rotations, while shallow high-residue cultivation can be coupled with banded herbicide application to control between row weeds and reduce total herbicide load.  Though high-residue cultivation has the potential to contribute to integrated weed management, one barrier to adoption is the lack of information regarding when and how often to use this tool for effective, efficient weed control.  An experiment was conducted at the Penn State Russell Larson Research and Education Center near State College, PA in the summer of 2011 to test the effects of different timings and frequencies of shallow high-residue cultivation on weed density and biomass and soybean density and yield.  A split-plot design was used in which no-till soybean was planted in 76-cm rows into a terminated cereal rye (Secale cereal L. cv. ‘Aroostook’) cover crop or into a low surface residue environment.  Prior to planting, the entire area was treated with 0.84 kg ae/ha glyphosate plus 0.56 kg ae/ha 2,4-DLVE and the cover crop was managed with a roller crimper.  At planting, 0.22 kg ai/ha metribuzin, 0.037 kg ai/ha chlorimuron and 1.42 kg ai/ha s-metolachlor were sprayed in a 25-cm band over the row.   Shallow high-residue cultivation treatments occurred at 4, 5 and 6 weeks after planting in all possible combinations and an uncultivated treatment was included for comparison.  Weed density data were collected immediately before the first cultivation and one week after the final cultivation in each plot.  Weed biomass data were collected on August 24 in all plots.  First year results showed that cultivation reduced weed biomass compared to the uncultivated check plots and that the reduction was greatest in treatments cultivated two and three times compared to a single or no cultivation.  Weed biomass amounts in treatments cultivated only once varied greatly depending on timing.  Frequency of rainfall and subsequent soil moisture as well as weed density and maturity at cultivation likely impacted control with more frequent rainfall generally reducing cultivator efficacy.  This experiment will be repeated in 2012 and expanded to include no-till corn planted into a hairy vetch cover crop.  Our results will provide insight into effective use of shallow high-residue cultivation and will inform decision-making associated with integrating alternative weed management strategies into no-till production systems.



This study evaluated the impact of soil properties on the effectiveness of microwave radiation for preemergence weed control. Controlling weeds prior to emergence avoids competition with the crop compared to postemergence weed control.  Obtaining preemergence weed control is a challenge for organic farmers, though, since few options are available. With the phase-out of  methyl bromide, additional preplant weed control measures are needed by growers using conventional methods. Conventional preemergence herbicides form a barrier in the soil to prevent weed seed germination or establishment. Their performance relies on favorable environmental conditions.   Long-residual chemicals can pose production concerns for subsequent sensitive crops.  Microwave radiations (2.45GHz), however, kills weed seed in soil before germination without leaving any residue and thus may be an option for organic and conventional growers. Microwave radiation penetrated soil depths up to 25 centimeters in our experiments, depending upon soil density, texture, and most important, soil moisture. Higher moisture content results in most of the radiation energy being absorbed in the upper soil layer, limiting downward penetration.  We observed greater control of southern crabgrass [Digitaria ciliaris (Retz.) Koel.] when seed was treated under lower compared to higher soil moisture levels when using a magnetron operating at 900 watt. The energy requirement for preemergence weed control using microwave radiation is comparatively much higher than that needed for postemergence weed control. Although certain properties like soil texture cannot be easily modified on a large scale, one can improve the effectiveness of microwave radiation for preemergence weed control by making applications at optimum soil moisture levels.



Through the 2007 Energy Independence and Security Act, the federal government has mandated tremendous increases in the production of cellulosic-based fuel. Many species of rhizomatous perennial grasses proposed for cultivation, bearing desirable traits for large-scale production, have caused concern for their potential to become invasive.  Therefore, one component of identifying the invasive risk of these potentially valuable crops is to conduct a weed risk assessment, which has become standard practice in many parts of the world. The Australian Weed Risk Assessment (A-WRA) has become the global standard, but the Animal and Plant Health Inspection Service (APHIS) PPQ weed risk assessment (PPQ-WRA) will be the new US standard for evaluating the invasive potential of new species. We compared the outcomes of both assessments to evaluate the invasive potential of proposed biofuel crops against invasive species that were introduced for agronomic purposes, as well as other agronomic crops that are not invasive.  These species include both known weeds such as Elymus repens and Dactylis glomerata, along with plants proposed for wide spread cultivation as biofuels including Arundo donax, Miscanthus sinensis, M. x giganteus, and Panicum virgatum. These two risk assessment models can be used to predict the invasive potential of future bioenergy crops in this emerging industry, with the potential to assist in future policy and management decisions.  Both assessments suggest that many of the leading biofuel candidates have the potential to become weedy in specific ecoregions of the United States.  Differences in the screening process are evident in the percentage of plants rejected by the Australian model (82%) in contrast to those receiving a high risk rating by the APHIS model (72%). However it should be noted, despite the similar percentage of high risk recommendation by the assessments, the species receiving acceptable or low risk ratings was not identical between the two assessments.  Befits of the PPQ-WRA include the ability to include uncertainty and leaves management decisions to other decision-makers. Based on the outcomes of these assessments we can be better prepared identify aspects contributing to potential invasiveness of these crops, while also planning ahead for improved stewardship in those that are predicted to be of high risk. 



Since the loss of mercury and other heavy metal based herbicides silvery threadmoss (Bryum argenteum) has become an increasing problem on golf course putting greens.  Superintendants continue to reduce mowing heights and fertility on putting greens to meet golfer demands for faster playing surfaces.  This creates optimal conditions for competitive displacement of creeping bentgrass by silvery threadmoss.  Only one herbicide, carfentrazone (Quicksilver) and two fungicides, chlorothalonil (Daconil) and mancozeb (Manzeb) are labeled for moss control on putting greens currently.  The objective of this study was to widely screen available crop protection chemicals for effects on silvery threadmoss and provide new options for its control on golf course putting greens. 

Two trials were initiated to examine herbicide effectiveness on silvery threadmoss.   Each was a randomized complete block design with ten replications and forty-nine herbicide treatments applied at one and two times the labeled use rates as well as a nontreated control.  After herbicide treatment, moss plugs were randomly placed into 24-well cell culture plates where they remained for the duration of the study.  Digital photos were taken for image analysis at 0, 3, 7, 10, 14, 21, and 28 days after treatment (DAT).  Each one was then cropped to include a single plot per image.  Data was captured in Sigma Scan Pro 5 and managed in ARM 8.  Sigma Scan was set to count green pixels in a range from hue=38 to 100 and saturation=0 to 100.  When compared to the zero-day after treatment pixel counts this provides a % reduction in green color for each moss plug which equates to a measure of control.  Data were subject to ANOVA and means separated by fishers protected LSD (p=0.05).  Herbicides which significantly reduced green color included: carfentrazone, flumioxazin, MSMA, glufosinate, sulfentrazone, and an experimental.  By 10 DAT, several herbicides reduced green color by more than 90% including flumioxazin, carfentrazone, fosamine, diquat, and sulfentrazone.  Successful treatments will be examined in the field next growing season to evaluate their efficacy and safety for potential supplemental registrations.

NATURAL HISTORY SURVEY OF THE. R.F. Dougherty*, L. Quinn, T. Voigt, B. Endres, and J.N. Barney, Virginia Tech, Blacksburg, VA (54)


Miscanthus sinensis is a perennial, C4 grass native to Southeast Asia. This species was introduced as an ornamental by the Biltmore estate in Asheville, North Carolina in the late 19th century.  Genetic testing has shown that this introduction was one of many, as the plant’s distribution quickly spread north to Washington DC and New York City by 1920.  Today M. sinensis remains a popular ornamental grass, with annual sales exceeding $39 million in North Carolina alone as of 2008. Miscanthus sinensis has since escaped the cultivated environment and naturalized across much of its introduced range, where it is now considered an invasive species. Miscanthus x giganteus, a sterile triploid hybrid of M. sinensis and M. sacchariflorus, is being used as a bioenergy crop with concern that it may escape and become invasive. Unlike the weedy parents, M. x giganteus does not produce seed, but has a much faster growth rate and grows much larger.

To better understand the invasiveness of the Miscanthus species, we must first characterize M. sinensis across its naturalized range in the United States to better understand its invasiveness.  This study surveys the current range of M. sinensis across the northeast from Tennessee to Maine. Demographic and environmental data was collected from populations in 20 locations.  Nearly all populations were located in low value, high disturbance areas such as roadsides, highways, railroads, power line right-of-ways, as well as abandoned gardens and nurseries.  Population sizes ranged from 15 individuals to over 1000.  These populations were compared across a large latitudinal gradient, which resulted in several significant trends.  Both average tiller height and approximate basal area decreased as populations moved north. In order to fully assess the risk of wide spread M. sinensis cultivation, we must continue to gain a better understanding of this species in its naturalized range. 



White-tailed deer (Odocoileus virginiana) affect invasive plant dynamics in forest understories. The argument stands that selective deer browsing could result in plant communities that are more susceptible to invasion, resulting in increases in exotic invasive plant abundance. As part of a region-wide analysis, deer exclusion studies revealed that while abundance of some invasive plants increased in the presence of deer, other invasive plants decreased. Differences in the palatability of native and non-native flora could explain this pattern. However, the palatability of weedy and invasive plants has not been directly investigated. In August and October 2011, we conducted deer preference trials using captive deer to test the palatability of eight exotic and seven native plant species that commonly occur in northeastern forests. Based on preliminary analysis of field plot data collected across the study region, we hypothesized that half of the native and half of the exotic species would be palatable to deer. We determined (1) percentage of leafy plant biomass of each trial species consumed by deer and (2) order of trial species preference by deer for each trial species using videography. Biomass and videography results indicate that Oriental bittersweet (Celastrus orbiculatus), Morrow’s honeysuckle (Lonicera morrowii), and common privet (Ligustrum vulgare) were highly palatable to deer. More than 78% of the leafy biomass of these three invasive plants was consumed, which was comparable to the consumption of the highly preferred native species, red maple (Acer rubrum) and Virginia creeper (Parthenocissus quinquefolia). Only 20% or less of garlic mustard (Alliaria petiolata) and Japanese stiltgrass (Microstegium vimineum) biomass was consumed in trials. Japanese barberry (Berberis thunbergii) was the least preferred species, with no browsing in August trials and consumption limited to 14% in October. Large populations of deer have the capacity to decimate populations of palatable plant species, granting a competitive advantage to unpalatable species. Minimal deer herbivory of unpalatable invasive plant species may help explain their large spatial extent and abundance in the study region. Explanations other than deer browsing likely explain why the highly preferred species (C. orbiculatus, L. morrowii, and L. vulgare) have become invasive, such as high growth rates and/or increased tolerance of deer herbivory.



Microstegium vimineum is a shade tolerant annual C4 grass that is an invasive species in the Mid-Atlantic and upper Southeastern US, and has been shown to negatively impact species diversity and composition in eastern native hardwood forests. Glyphosate (2% spray to wet) is currently the most common method for controlling M. vimineum invasions.  However, little information exists on the long-term efficacy, costs, and non-target consequences of large-scale eradication of this understory invader. Therefore, a study was established in Southwest Virginia to compare the cost and efficacy of understory management practices that included mechanical removal (string trimmer) and spot applications of standard rate glyphosate (2%), reduced rate glyphosate (0.045 kg ai ha-1), and sethoxydim (1.5% spray to wet).   We used a split-plot design to assess the efficacy of both a single seasonal application, and a multiple application treatment with the management goal of 100% M. vimineum control. 

Prior to treatment, M. vimineum groundcover was 51% (±18.6%).  Costs of fuel, herbicide, and labor were recorded for each plot to find the total cost of management per treated hectare.  Plant community data was recorded before and after treatment application to assess the non-target species effects.  Sethoxydim, standard rate glyphosate, and reduced rate glyphosate achieved near 100% M. vimineum control with a single application.  Impact on non-target species was greatest in standard rate glyphosate plots (26% cover reduction) and lowest in sethoxydim plots (3% cover reduction).   Sethoxydim also had no effect on tree seedling recruitment unlike all other treatments, which were reduced by 15-26%.  Labor was >95% of total cost for all treatments, and herbicide costs did not greatly differ.  On average herbicide treatments cost $237 ha-1 for single treatments and $348 ha-1 for 100% control (multiple applications).  Mechanical treatment was >200% more expensive than any herbicide application due to longer application time requirements.  It appears that a single treatment of low-rate glyphosate or sethoxydim was adequate for single-season M. vimineum control.  The additional cost of labor for multiple applications per season may be unnecessary, and glyphosate has the greatest negative impact on the surrounding community.  Both reduced rate glyphosate and sethoxydim are just as effective while having reduced impacts on the native flora, which may be alternative methods for managers in M. vimineum management.



The herbicides mesotrione and topramezone inhibit 4-hydroxyphenylpyruvate dioxygenase (HPPD) and have efficacy against smooth crabgrass (Digitaria ischaemum). Research was conducted to determine the impacts of soil-applied nitrogen (N) fertilizer on the efficacy of mesotrione and topramezone for smooth crabgrass control.

Dose-response experiments evaluated the response of smooth crabgrass to mesotrione (0, 70, 140, 280, 560 and 1120 g ha-1) and topramezone (0, 4.5, 9, 18, 36 and 72 g ha-1) with 0 or 49 kg N ha-1. Smooth crabgrass was seeded into 10-cm pots filled with a Sequatchie silt loam soil blended with calcined clay in a 3:1 ratio. Treatments were applied with small-plot spray equipment at 280 L ha-1 to 3- to 5-tiller crabgrass plants. Percent visual control was evaluated 4, 7, 14 and 21 days after treatment (DAT). Aboveground dry biomass was determined 21 DAT. Log-logistic regression analyses were conducted to determine the herbicide dose required to provide 50% visual crabgrass control (I50).

 Further greenhouse research evaluated changes in visual necrosis, weight, chlorophyll and carotenoid pigment concentrations of smooth crabgrass leaf tissue following treatment with mesotrione (280 g ha-1) and topramezone (18 g ha-1) with 0 or 49 kg ha-1. Smooth crabgrass was seeded into 20-cm pots filled with a Sequatchie silt loam soil blended with calcined clay in a 3:1 ratio. Treatments were applied using a spray chamber at 430 L ha-1 to 3- to 5-tiller crabgrass plants. Leaves present at the time of herbicide application (except for the bud leaf) were marked with indelible ink, designating leaves as those fully emerged before and after herbicide application. Chlorophyll and carotenoid pigments were extracted from leaf tissue harvested 10 days after treatment and quantified via high-performance liquid chromatography. All herbicide treatments were applied with a NIS at 0.25% v/v.

 In dose-response experiments, N application reduced I50 values for mesotrione and topramezone by 50 and 65%, respectively, 21 days after treatment (DAT). Reductions in aboveground biomass with both herbicides were greater when applied following N treatment as well. In leaf-response experiments, N decreased total chlorophyll and xanthophyll cycle pigment concentrations and weight of leaves that emerged after treatment with topramezone. Treatment with N also increased necrosis of leaves emerged after herbicide application in mesotrione-treated plants. Responses of leaves fully emerged before herbicide treatment were not affected by N. Future research should investigate whether increased translocation of these herbicides to meristimatic regions contributed to N-enhanced efficacy.

QUANTIFYING VAPOR DRIFT OF DICAMBA HERBICIDES APPLIED TO SOYBEAN. J. Egan* and D. Mortensen, Pennsylvania State University, University Park, PA (58)


Recent advances in biotechnology have produced cultivars of corn, soybean, and cotton resistant to the synthetic auxin herbicide dicamba. This technology will allow dicamba herbicides to be applied in new crops, at new times of years, and over greatly expanded acreages, including postemergence applications in soybean.  From past and current use in corn and small grains, dicamba vapor drift and subsequent crop injury to sensitive broadleaf crops has been a problem. In this study, we measured dicamba vapor drift in the field from postemergence applications to soybean using greenhouse-grown soybean as a bioassay system.  We found that when the volatile DMA formulation is applied, vapor drift could be detected at mean concentrations of 0.561 g a.e. dicamba/ha (0.1% of the applied rate) at 20 m away from a treated 18.3m x 18.3m plot. Applying the DGA formulation of dicamba reduced vapor drift by 96.0%.  With the DMA formulation, the extent and severity of vapor drift was significantly correlated with air temperature, indicating elevated risks if DMA dicamba is applied early to mid-summer in many growing regions.  Additional research is needed to more fully understand the effects of vapor drift level exposures to non-target crops and wild plants.



Johnsongrass (Sorghum halepense) is a common and difficult to control weed in corn production.  The uses of glyphosate- or glufosinate-tolerant corn varieties has led to a decrease in the number of herbicide modes of action used in field corn.  Producers planting these varieties typically rely on glyphosate/glufosinate or nicosulfuron as their main options for grass weed control.  This change in herbicide use patterns has inadvertently led to increased selection pressure for weedy biotypes resistant to these herbicides.  Research has confirmed glyphosate and nicosulfuron resistant johnsongrass, but there are no reports of multiple resistance to these herbicides.  A nicosulfuron-resistant johnsongrass population was reported to have failed to be controlled by 0.88 kg a.e. ha-1 of glyphosate for two growing seasons in Virginia.  Field experiments subjected johnsongrass to four rates of nicosulfuron and five rates of glyphosate.  Visual control was measured and seed was collected from surviving johnsongrass plants.  At 0.88 kg a.e. ha-1, control with glyphosate was 65%.  At 3.52 kg a.e. ha-1, control was 90%.  At 0.057 kg a.i. ha-1, control with nicosulfuron was 9%.  In greenhouse experiments using johnsongrass seedlings grown from collected seed, glyphosate at 0.22 kg a.e. ha-1 and 0.44 a.e. ha-1 provided no control, but surviving seedlings had visibly diminished vigor.  Experiments were conducted to evaluate differential glyphosate sensitivity between individual biotypes.  Several biotypes, when compared to a wild type, failed to be controlled by 0.22 kg a.e. ha-1 and 0.44 kg a.e. ha-1 rates of glyphosate.  Additionally, greenhouse experiments were conducted with rhizomatous plants.  Several individual plants treated with 0.22 kg a.e. ha-1 of glyphosate, while visibly injured, had increased vigor when compared to a wild type receiving the same rate.  Moreover, plant regrowth was measured and several individuals had regrowth after application.  These results suggest that this suspect johnsongrass population may exhibit differential sensitivity to glyphosate, but additional confirmation is needed. 

THE NON-NATIVE VASCULAR FLORA OF MONOMOY ISLANDS, MASSACHUSETTS. r. stalter*, st johns university, queens, NY (60)







            The objective of the present study was to prepare a preliminary list of the non-native vascular plant species at Monomoy  Islands National Wildlife Refuge, Massachusetts. Collecting trips were made to the islands during the growing seasons beginning September 2010 to September 2011 for the purpose of collecting voucher specimens. The preliminary flora consists of  126 species of which 26 are not native to coastal Massachusetts.






            Monomoy Island Wildlife Refuge, (41.56 N latitude, 69.99W longitude) comprising 1317 hectares, is composed of two barrier islands, North Monomoy and South Monomoy extending southward at the bend of Cape Cod from Morris Island, Massachusetts (Lortie et al 1991) Prior to 1958, the land was a spit extending south from Morris Island. The spit was breached at its northern terminus by an April storm in 1958 creating on large island, Monomoy Island. The second disturbance of note was the nor’easter/blizzard of February 6 and 7, 1978, which  breached by the island  approximately 3 km below the north end creating the two islands that exist today.

            Barrier Islands have an active geological history (Leatherman 1979). Waves, wind, tides, and severe storms have sculpted and modified Monomoy Island. Lortie et al (1991) have  provided extensive information on the geomorphic changes on the island over the past 200 years and  changes in its plant communities and vascular plant species. The island’s most mature plant community, the woody thicket, and a large freshwater marsh were destroyed by the nor’easter of February 1978. A number of taxa, noted by previous investigators,  Carex debilis, Smilax rotundifloria, and Smilacina stellata, collected at the  thicket community  at Inwood Point, were probably extirpated at Monomoy Island when  the woody thicket  was destroyed by the 1978 nor’easter.

            The primary objective of this study was to prepare a preliminary  list of the native and non-native  vascular plant species at Monomoy Islands National Wildlife Refuge, Massachusetts (Table 1).  A second objective was to compare the percentage of non-native plant species at Monomoy Islands with the non-native plant species  present at other nearby coastal sites (Table 2).  A third objective was to compare the vascular plant floras of Monomoy Island prepared by various investigators from 1954 to the present (Table 3).










            The vascular flora at Monomoy Island was sampled monthly during the growing season  from September 2010 to September 2011.  Two whole plants or portions of plant material of each specific taxon were collected, dried, identified and mounted on herbarium paper. Voucher material will be  deposited at the A.C. Moore Herbarium, at the University of South Carolina. Rare and/or endangered species were photographed.

            Vascular plant species were classified according to Gleason and Cronquist (1991). Native and non-native status of each taxon follows Gleason and Cronquist (1991). The status of rare, threatened, and endangered vascular plants follows the latest edition of the Massachusetts Heritage Program (  The study will end September, 2012, the latest month in the 2012 growing season when boat transportation to the island will be available to Stalter.






            The preliminary list of the vascular flora at Monomoy Island consists of 126 species in 99 genera in 50 families. The largest family in the flora was Asteraceae (24 species); no other family had more than 10 species. Native species, 79.4% of the flora, were the major component of the flora. Polygonum glaucum, a coastal dune species was the only Massachusetts endangered or threatened species of the flora.

            Monomoy’s non-native plant species, 20.6% of the flora, was only slightly higher than the percentage of non-native vascular plant species on Gardiner’s Island observed by Hehre (1977), 19.1%. Both Gardiner’s and Monomoy experience little human activity. National Fish and Wildlife Refuge personnel observe and record bird and seal populations at Monomoy.  Portions of Monomoy’s dune community are burned each October to provide appropriate nesting habitat for the island’s tern populations. Gardiner’s Island has been occupied by a succession of Gardeners since the 1600s! With the exception of a caretaker and ornithologists involved with a Christmas bird count, no “outsiders” have access to the island (Table 2). Plum Island, the site of the USDA’s Animal Disease Research Center, has limited human disturbance, the activity of the scientists who work at the main laboratory and at the animal research facilities. Great Gull Island, a small island east of Plum Island, has no permanent residents, but is the site of the American Museum of Natural History’s tern research colonies. The land at Great Gull Island is plowed and mowed yearly each spring to provide appropriate habitat for nesting terns; the plowed soil provides excellent habitat for invasive non-native vascular plants.  The percentage of alien non-native taxa At Orient Beach State Park, N.Y. is misleading.  Humans rarely visit the    western portion of the park which   supports a non-native plant species population of approximately 20% while the often visited eastern side of the park has a non-native plant species population of greater than 40% (Table 2). Human population density may be related to non native species richness on coastal northeastern islands (McMaster 2005).   While population density influences species diversity, MacMaster (2005)   found that the influence of island area was approximately six times stronger than that of human population density in his study of vascular plant diversity on 22 coastal islands.

            Monomoy Island’s vascular flora has been documented since 1954 (Table 3).  The earliest investigators, Cross and Cross recorded 66 plant species in 1954. The greatest number of plant species was recorded by Lortie et al, who identified 201 species during their 8 year study, 1981-1989. The most recent study by Stalter, September 2010/2011 included 135 taxa  Additional plants will be added to this list when the grasses (Poaceae)  and sedges (Cyperaceae) are identified  and additional plant species are collected and identified during the   2012 growing season. 






BAILEY, W. 1965. Plant List of Monomoy National Wildlife Refuge, Massachusetts. Contribution No. 2, Monomoy Light Research Station. Massachusetts Audubon Society, South Wellfleet, MA.

GLEASON H.A. & A. CRONQUIST. 1991. Manual of Vascular Plants of Northeastern United States & Adjacent Canada. 2nd Ed. The New York Botanical Garden, Bronx. 910.                 HEHRE, E.J.  1977. The flora of Gardiners Island. Rhodora 79:214-239.

LEATHERMAN, S.P. 1979. Barrier Islands Handbook. National Park Service Cooperative Research Unit.          University of Massachusetts, Amherst, MA.

LAMONT, E.E. & R. STALTER. 1991. The Vascular Flora of Oriental Beach State Park, Long Island, New York. Bull. Torr. Bot. Club 118: 459-468.                                                         

MCMASTER. R.T.  2005. Factors influencing vascular plant diversity on 22 islands off the coast of eastern North America. J. Biogeography 32: 475-492.

MOUL, E.T. 1969. Flora of Monomoy Island, Massachusetts. Rhodora 71:18-28.



Table 1. A statistical summary of the vascular flora of the Monomoy Islands, Massachusetts


Spore Plants























Native Species






Introduced Species












Table 2. Frequencies of native versus non-native plants at Plum Island, NY, Orient Beach State Park, NY (Lamont and Stalter 1991), Gardner’s Island,  NY (Hehre 1977), Great Gull Island,  NY (Stalter and Lamont 2001), and Monomoy Islands, MA.


Plum Island, NY

Gardner’s Island, NY

Great Gull Island, NY

Orient B., NY

Monomoy Islands, MA

Native Species






Non-Native Species






%Non-Native Species






Total Species









Table 3. Summary of the flora of Monomoy Islands, prepared by various investigators from 1954 to 2011. The floras listed chronologically, are those of Cross and Cross (1954) in Lortie et al (1991), Bailey (1965), Moul (1969), Lortie et al (1991) and Stalter (2011).






Lortie et al


Spore Plants































COMPOST INCREASES WEED ABUNDANCE IN AN ORGANIC GRAIN CROPPING SYSTEM. C.A. Marschner*, C.L. Mohler, B.A. Caldwell, and A. DiTommaso, Cornell University, Ithaca, NY (61)


A long term cropping systems experiment in central New York State compared three organic systems that differ in nutrient inputs and intensity of weed management.  The three systems were: a moderate nutrient-input system that approximated Cornell University fertility recommendations using chicken manure compost as the principal nutrient source; a low input system that minimized inputs to control costs; and a weed control system that combined low inputs with intensive weed management.  The three cropping systems employed a three year rotation of corn, soybean and spelt undersown with red clover.  Two of the three crops were grown each year.  The experiment was conducted on moderately well drained silt loam soil, and results are presented for 2005-2011.  Weed biomass increased over time to some extent in all three systems, but weed biomass  in the low-input and intensive weed management systems, rarely exceeded 500 kg/ha at early August sampling and was often less.  This level of weed pressure is acceptable to most organic grain producers. Weed biomass in the standard fertility system increased to a much higher level than the two lower-input systems.   The corn and soybean yields in all three systems were the same, but spelt yields were higher with the additional nutrients.  Several weed species responded more strongly to nutrient additions than did corn or soybean, leading to serious weed problems over time.  Using typical university fertility recommendations for corn and soybeans in an organic system did not increase yields and contributed to weed problems.

INITIAL INVESTIGATIONS INTO DODDER SPECIES VARIATION IN SOUTHEASTERN MASSACHUSETTS. K.M. Ghantous*, S. Stefanovic, and H.A. Sandler, University of Massachusetts, Amherst, MA (62)


Dodder (Cuscuta spp.) is an obligate parasitic plant that can infest cranberry bogs and presents a significant threat to cranberry yields.  This weed is being reported on increasing numbers of farms, and its control is a high priority goal for Massachusetts cranberry growers.  The species found on cranberry bogs has been traditionally considered to be Cuscuta gonovii.   Dodders are very difficult to distinguish, and their taxonomy based on morphology is controversial.  Dodder populations have been reported with visual variations in stem color, stem thickness, and temporally distinct flowering times.  We speculated that some of these variations in phenotype may actually be variations in genotype. In addition, growers and researchers alike have experienced and reported variable results and/or failures when managing this pest with herbicides or/or non-chemical methods.    Subsequent discussions lent some credence to the possibility that differences in dodder species or ecotypes may play a role in the inconsistent management of dodder on some farms. 

Our objectives were to survey at least two dozen sites, collect dodder stems, and use DNA to identify which species are present in Southeastern Massachusetts. During the 2011 season, we collected dodder samples from 41 sites consisting of 39 commercial bogs and 2 naturally occurring populations.  The sampled sites represented 23 towns, most of which were in a 25 -mile radius around Carver, MA, the production center of the cranberry growing region.  Dodder samples were sent to a DNA laboratory where polymerase chain reaction (PCR) was used to identify species.  Identifications are being made based on recent work on dodder phylogeny by Stefanovic et al. (American Journal of Botany 94(4): 568–589. 2007).  Preliminary results from 5 bogs indicate that at least one species in addition to C. gronovii is present in Southeastern Massachusetts.

EARLY SEASON PHENOLOGICAL INDICATORS OF CEREAL RYE PERFORMANCE. S. Mirsky*, J. Spargo, W.S. Curran, M.R. Ryan, and S. Reberg-Horton, USDA-ARS, Beltsville, MD (63)


Cover crops have the potential to be used as multifunctional tool to enhance ecosystem services. However, maximizing the function of one service can hinder the performance of another. For example, cereal rye (Secale cereale) is used to both scavenge nitrogen (N) and suppress weeds. High levels of cereal rye biomass are necessary for adequate nonchemical weed suppression when used as a mulch. Residual inorganic soil nitrogen in the fall may not be sufficient to achieve biomass levels in the spring necessary for weed suppression. Several cover crop cost share programs prohibit fall applications of fertilizer. Furthermore, inadequate cereal rye biomass levels should be incorporated through tillage, in early spring, in order for optimal seedbed preparations. Early spring cereal rye phenological traits that effectively estimate mature cereal rye biomass and responsiveness to nitrogen fertilizer applications can aid with farmer decision making. We tested the effects of fall and spring soil N levels on cereal rye biomass accumulation at anthesis, and the relationships between spring shoot density at tillering and shoot elongation with mature cereal rye biomass. A normalized vegetation index (NDVI) was calculated using remote sensing techniques (active crop canopy reflectance sensors) and regressed with mature cereal rye biomass. Cereal rye shoot density at the tillering stage and NDVI measurements were both good estimates of mature cover crop biomass.  Due to annual variations in the relationship between NDVI, at tillering, with mature cereal rye biomass, site-specific calibration may be required.  

BEDDING PLANT RESPONSE TO DIMETHENAMID. J.F. Derr*, Virginia Tech, Virginia Beach, VA (64)


There are limited options for weed management in bedding plants.  Dimethenamid, a relatively new herbicide for the nursery and landscape industries, may be an option for weed control in annual flowers.  Both a sprayable EC formulation (Tower) and a granular product containing dimethenamid plus pendimethalin (FreeHand) were evaluated in field trials. 

          No injury to  gazania ‘Rose Kiss Hybrid’ , marigold ‘Queen Sophia’ , vinca ‘Pacifica Lilac’ , lanceleaf coreopsis ‘Early Sunrise’ , geranium ‘Multibloom Red’ , coleus ‘Wizard Mix’  was seen 8 DAT at FreeHand rates ranging from 1.75 to 7.0 lb ai/A.  There was no reduction in flowering at 20 DAT.  At 29 and 51 DAT, flower count in marigold and vinca decreased as the FreeHand rate increased, but there was no reduction at 1.75 lb ai/A when compared to the untreated.  At 41 DAT, vinca flower count decreased as the FreeHand rate increased.  Reduced flowering in gazania was noted at the highest rate of FreeHand at 41 and 51 DAT.  At 58 DAT, marigold flower count decreased as the FreeHand rate increased but less reduction in vinca flowering was noted compared to earlier counts.  At 60 DAT, there was injury (29%) in coleus at the highest FreeHand rate, but no injury was noted in marigold, vinca, or lanceleaf coreopsis. 

    At 15 DAT, reduced flowering in impatiens ‘Dazzler Orange’, alyssum ‘Wonderland Rose’, and petunia ‘Fantasy Red’ was noted as the FreeHand rate increased.   At 27, 37, and 45 DAT, impatiens flower count decreased as FreeHand rate increased, but no decrease was seen in petunia, vinca ‘Pacifica Lilac’, geranium ‘Multibloom Red’, or zinnia angustifolia ‘Stargold’.  At 27 and 37 DAT, there appeared to be a slight decrease in vinca flowering at the highest rate of FreeHand.    At 47 DAT, injury was only seen at the highest rate of FreeHand in impatiens and alyssum, with no injury at lower FreeHand rates. 

Tower at 1.0 to 4.0 lb ai/A and FreeHand at 2.6 to 10.5 lb ai/A appeared to reduce flowering in zinnia ‘Stargold’ at 15 and 22 DAT, but no reductions were noted at 36 DAT.  The highest rate of Freehand injured ‘Magnus’ purple coneflower and gazania.   Flowering in purple coneflower appeared to decrease as the FreeHand rate increased.  The highest rate of FreeHand and Tower reduced flowering in impatiens.   In begonia ‘Cocktail Vodka’, flower count and plant stand decreased significantly as the Tower or FreeHand rate increased.  In alyssum ‘New Carpet of Snow’, flowering decreased as the Tower or FreeHand rate increased.  The highest rate of both chemicals reduced alyssum stand.  In impatiens ‘Super Elfin Hot Mix’, flowering decreased as the Tower or FreeHand rate increased at 30, 41 and 75 DAT.

Gazania, marigold, vinca, petunia, lanceleaf coreopsis, geranium, purple coneflower, zinnia, and coleus appear to have good tolerance to FreeHand at the 1.75 lb ai/A rate, but some reduction in flowering can occur at 4 times that rate.  Flowering in impatiens decreases as the FreeHand rate increases. The cultivars of begonia, alyssum, and certain ones of impatiens used in these trials do not have acceptable tolerance to Tower or FreeHand.



Early postemergence control of bittercress (Cardamine hirsuta) was evaluated using preemergent active herbicides. Bittercress seed were surface sown by hand onto 3.5 inch pots filled with a pinebark:sand (6:1 v:v) media that had been previously amended with standard fertilizer amendments on April 6, and April 18, 2011 in separate pots resulting in two stages of growth: 2 to 4 leaf (2-4L) and 6 to 8 leaf (6-8L) stages. On April 28, 2011, all bittercress were treated with the following herbicides: Dimension 2 EW [0.5 lbs active ingredient per acre (ai/A)], Gallery 75DF (0.66 lbs ai/A and 1.0 lbs ai/A), and Showcase (5 lbs ai/A). Spray-applied herbicides were applied with a CO2 backpack sprayer (80-04 nozzle, 25 psi) using an application volume of 60 gallons of water per acre. Showcase was applied using a hand-shaker. Herbicides were applied to dry foliage and bittercress received no irrigation for 3.5 hours except for bittercress treated with Showcase which were sprinkled with water prior to treatment. Bittercress were grown under a shade structure and received daily irrigation via overhead impact sprinklers (0.5 in). Postemergence control was assessed at 1, 2, 3, and 4 weeks after treatment (WAT) on a scale of 0 to 100, 0 = no injury, 100 = dead plant. Fresh weights were also taken at 30 days after treatment. At 4 WAT, bittercress in the 2-4L stage had the highest injury ratings (100) when treated with Gallery (both rates), followed by bittercress treated with Showcase (90) and Dimension (83.8). All bittercress receiving a herbicide treatment had similar fresh weights at the conclusion of the study. Once bittercress reached the 6-8L stage, control ratings dropped slightly in all treatments. At 4 WAT, bittercress had injury ratings of 86 or higher when treated with Gallery (both rates), or Showcase. At this time, bittercress treated with Dimension had injury ratings of 60.0 and injury ratings were significantly less than all other herbicide treatments. Fresh weights indicated that Gallery (both rates), and Showcase all provided similar bittercress control. Bittercress treated with Dimension had higher fresh weights than bittercress treated with other herbicide treatments, but were significantly less than the non-treated control, indicating that Dimension had some postemergence activity. Results from this trial indicate that bittercress can be effectively controlled in the 2-4L stage with Gallery, Showcase, and Dimension at label rates. Once bittercress reached the 6-8L stage, Dimension was less effective as a postemergent application, but did provide some postemergent activity when compared to non-treated plants.

IR-4 2011 CROP INJURY SUMMARY OF SEVERAL HERBICIDES ON ORNAMENTAL NURSERY CROPS. K.A. Hester*, C.L. Palmer, E. Vea, and J. Baron, The IR-4 Project, Exton, PA (66)


The 2011 IR-4 Ornamental Horticulture Research Program sponsored crop safety testing of over-the-top applications on several different herbicide products. Biathlon (oxyfluorfen + prodiamine) was tested on 9 crops, Broadstar 0.25 VC1604 (flumioxazin) on 5 crops, Certainty (sulfosulfuron) on 25 crops, F6875 (sulfentrazone + prodiamine) on 20 crops, Freehand G (dimethenamid-p + pendimethalin) on 40 crops, Gallery (isoxaben) on 9 crops, indazaflam on 17 crops, mesotrione on 13 crops, Sedgehammer (halosulfuron) on 13 crops, Snapshot (trifluralin + isoxaben) on 31 crops, and Tower EC (dimethenamid-p) on 24 crops. The goal of this research was to screen these herbicides for safety on container grown woody ornamentals and herbaceous perennial crops in nurseries. Applications were made at dormancy and approximately 6 weeks later for all products with the exception of Broadstar 0.25G VC1604 which was applied once at the later application date. The results from this research will aid in the development of the product labels and will help growers and landscape care professionals make more informed product choices.


IR-4 2011 SUMMARY OF POSTEMERGENT LIVERWORT CONTROL IN NURSERY CONTAINERS. K.A. Hester*, C.L. Palmer, E. Lurvey, and J. Baron, The IR-4 Project, Exton, PA (67)


The 2011 IR-4 Ornamental Horticulture Research Program sponsored efficacy testing of several postemergent herbicides for liverwort, Marchantia sp., control in containers grown primarily under cover in greenhouses and hoop houses where few herbicides are registered for use. Applications were made across the United States using Bryophyter (oregano oil), FlowerPharm (cinnamon and rosemary oil), Greenmatch (d-limonene), Racer (ammonium nonanoate), Scythe (pelargonic acid), Sporotec (rosemary, clove and thyme oil), SureGuard (flumioxazin), Terra Cyte Pro G (sodium carbonate peroxyhydrate), Tower (dimethenamid-p), and WeedPharm (acetic acid). The results from these trials provide ornamental growers information on postemergence herbicides effective in controlling this troublesome pest, as well as, data for label expansion.



Triamine II, Tri-Power, and Triplet Low Odor safeties to Miscanthus sinensis ‘Gracillimus’ and Muhlenbergia capillaris were evaluated. The experiment was conducted at Hoffman’s Nursery, Rougemont, N.C., a specialty nursery that focuses on ornamental grass production. Plants were irrigated as needed and insect pests were controlled by the nursery personnel according to common grower practice. Divisions of Miscanthus sinensis ‘Gracillimus’ and seedlings of Muhlenbergia capillaris, in 3.5 inch cells, were potted to 1 gallon containers using a pine bark/peanut hull/coir based substrate on July 20, 2010. Plants were maintained under standard nursery practices until new growth was adequate for postemergence herbicide phytotoxicity evaluations.  Treatments included a non-treated control, Triamine II @ 3, 6, and 12 pt/A, Tri-Power @ 3, 6, and 12 pt/A, and Triplet Low Odor @ 2.5, 5, and 10 pt/A. Treatments were arranged in a randomized complete block design with 4 replicates and 3 plants of each species per plot. Herbicide treatments were applied on August 4, 2010 and reapplied on September 16, 2010. Miscanthus showed no injury of practical significance following the first application in all treatments. Following the second application, foliage was uninjured by 1X applications of Triamine II and Triplet Low Odor but was injured by all higher doses and all doses of Tri-Power.  All herbicides reduced flowering at all application rates. Muhlenbergia foliage was uninjured by 1X applications of the herbicides throughout the experiment and showed little injury following the first application of the 2X rates. Significant injury was seen at 4X rates and following the second application of the 2X rates. However, Muhlenbergia flowering was reduced by all herbicides at all application rates. The experiment is being repeated in 2011.




We conducted two experiments in 2011 to evaluate herbicide tolerances of ornamental grasses (Experiment 1) and woody shrubs (Experiment 2) in containers.

           In Experiment 1, species were Calamagrostis x acutiflora ‘Avalanche’ (feather reed grass), Panicum virgatum ‘Heavy Metal’ (switch grass), Pennisetum alopecuroides ‘Hameln’ (fountain grass) and Schizachyrium scoparium ‘Prairie Blues’ (little bluestem).  Plants were potted in 1-gallon containers on June 29.  Each plot contained three pots of each species plus three plantless pots (container mix only).  Treatments were replicated four times in a RCB design.  Sprays were applied at 50 gal/A using a CO2-pressurized boom with TeeJet 8004VS tips.  All treatment solutions (including the control) contained non-ionic surfactant (0.25% v/v).  Treatments were mesotrione (Tenacity 4F) at 0.187 lb ai/A and at 0.374 lb ai/A, mesotrione at 0.187 lb ai/A plus s-metolachlor (Pennant Magnum) at 1.91 lb ai/A, and mesotrione at 0.187 lb ai/A plus prodiamine (Barricade 65WG) at 0.65 lb ai/A.  Treatments were applied on July 5 (T-1) and August 4 (T-2) over the top of dry foliage.  Overhead irrigation for 45 min began 2 to 4 h later.  On July 15, seeds of large crabgrass (Digitaria sanguinalis) were spread in all plantless pots.

           Plant injury (0 to 10 scale) was observed as foliar whitening due to mesotrione.  The injury level was not affected by s-metolachlor or prodiamine.  The following injury ratings were recorded on July 19 (2 WAT-1):  Calamagrostis, 0 to 0.7; Schizachyrium, 0.7 to 1.6; Pennisetum, 1.0 to 2.2; and Panicum, 2.3 to 2.8.  By August 1, whitening had decreased on all grasses.  On August 18 (2 WAT-2), injury on Panicum ranged from 1.5 to 3.2, but all other grasses had injury ratings below 1.  Injury to Panicum subsided but remained significant in September.  Crabgrass control (0 to 10) was evaluated on August 1 (PRE activity after T-1) and September 21 (PRE + POST activity after T-2).  Mesotrione at 0.187 lb ai/A was not effective at controlling crabgrass (<4 at both ratings).  Mesotrione at 0.374 lb ai/A provided better control:  6.7 on August 1, and 9.2 on September 21.  Mesotrione combined with s-metolachlor or prodiamine had crabgrass control ratings of 9.4 to 9.8 on both dates.

           In Experiment 2, plants were Clethra alnifolia ‘Hummingbird’ (summersweet), Cornus kousa (Kousa dogwood), Hydrangea macrophylla ‘Endless Summer’ and Tsuga canadensis (eastern hemlock).  Plants were potted in 1-gallon containers on May 23.  The experimental design (without plantless pots) and spray applications (without surfactant) were as described above.  Granules were applied with a calibrated auger-feed drop spreader.  Treatments [dimethenamid-P (Tower 5.9EC) at 0.97, 1.94 and 3.88 lb ai/A, and dimethenamid-P plus pendimethalin (FreeHand 1.75G) at 2.65, 5.30 and 10.6 lb ai/A] were applied on June 28 (T-1) and August 4 (T-2).  For all treatments and timings, Clethra and Cornus had injury ratings <0.7.  After T-1, minor injury was observed on Hydrangea treated with FreeHand and on Tsuga treated with Tower.  At 3 WAT-2, Hydrangea treated with the highest dose of FreeHand had an injury rating of 2.0, and Tsuga treated with the highest dose of Tower had an injury rating of 1.8.



Certain container grown ornamental crops are vulnerable to invasion from monocotyledonous weeds such as yellow nutsedge (Cyperus esculentus), rice flatsedge (Cyperus iria) and annual grasses. In 2011, a local commercial nursery growing hydrangea cultivars and perennials such as Achillea millefolium 'Moonshine' and Perovskia atriplicifolia ‘Little Spire’became heavily infested with these weeds shortly after the crops were transplanted outdoors. Yellow nutsedge was the most severe weed species, however, several annual grasses such as fall panicum (Panicum dichotomiflorum) and large crabgrass (Digitaria sanguinalis) were also very competitive. Bentazon can be an effective management tool of yellow nutsedge. Some historical data indicates a level of tolerance to bentazon from some these ornamentals. Fenoxaprop-P and sethoxydim were evaluated for post emergence control of the annual grasses. The trial was conducted at a commercial nursery on Long Island, NY. Spray treatments were applied on July 8, 2011 and again on July 20, 2011. Treatments were applied over the top with standard CO2 backpack equipment. Bentazon was evaluated at 0.375 and 0.5 lbs./a (a.i.) with and without 0.5% methylated seed oil. Fenoxaprop-P and sethoxydim were evaluated at 0.373 lbs./a (a.i.), alone and with bentazon. Visual evaluation of crop response and control efficacy was recorded four times after treatment.

The results indicate that the hydrangea cultivars tested were severely injured by all rates and combinations of bentazon. Perovskia was well tolerated by all treatments. Achillea was moderately injured by bentazon, but tolerated sethoxydim well.

Yellow nutsedge was well controlled by both rates of bentazon even without adjuvant. Annual grass control was excellent with sethoxydim or fenoxaprop-P.

These results suggest that bentazon is not a good candidate for registration as an over the top treatment on modern hydrangea cultivars. However, further testing on the two perennial species appears to be warranted.

SAFETY AND EFFICACY OF MULCH AND MULCH / HERBICIDE COMBINATIONS IN PANSY BEDS. J.C. Neal*, C. Harlow, and B. Fair, North Carolina State University, Raleigh, NC (71)


The safety and efficacy of mulches and mulch / herbicide combinations were evaluated in pansy (Viola x wittrockiana ‘Giant Yellow’).  Prior to planting the field bed was rototilled and fertilizer incorporated at a rate of 1 lb N per 1000 sq. ft.  On November 11, 2010, five pansy plants, grown in 18-cell packs, were planted in the center of each sq meter plot.  After planting, mulches and herbicides were applied.  Treatments included:  Bare soil and no treatment, bare soil treated with Preen (trifluralin 1.47G) @ 4 lb ai/A, composted leaf mulch, triple shredded hardwood bark, Pine straw +/- Preen, pine bark mulch +/- Snapshot TG (trifluralin + isoxaben 2.5G), black dyed wood chips (Bella Vista) or black dyed wood chips impregnated with 0.0033% trifluralin + 0.00008% isoxaben (Preen Plus Mulch).  Each mulch was applied to a depth of one inch (= one cubic foot of mulch per sq m).  Treatments were arranged in a randomized complete block design with 4 replications.  In a separate area, these treatments were repeated in the absence of pansy plants for weed control evaluations.  Additional treatments included in the efficacy experiment were pine bark mulch top dressed with 2.65 lb ai/A Freehand (dimethenamid-p + pendimethalin 1.75G) or 3 lb ai/A Pendulum 2G and wood chips impregnated with trifluralin (Bella Vista with Weed Block).  In both tests, henbit plants per plot were counted in March and April.  Weeds were hand-removed from the pansy test to minimize competition.  Pansy plant quality was visually evaluated monthly in the spring on a 0 to 5 scale where 5 = the best plants in the test and 0 = all plants dead.  Pansy flowers were counted on March 2nd and April 4, 2011.  Similar to prior reports, pine straw reduced pansy growth and flowering compared to non-treated plants.  Snapshot applied at 3.75 lb ai/A also reduced pansy flowering and growth.  Triple shredded hardwood bark mulch reduced early season pansy vigor and final fresh weight, but did not reduce flower counts.  Herbicide impregnated mulches did not reduce pansy growth or flowering.  Henbit control was good with all herbicide and herbicide + mulch combinations.  Pine straw, pine bark, leaf mulch and hardwood bark reduced henbit populations greater than did wood chip mulches alone. 

TOLERANCE OF CONIFERS TO MESOTRIONE ALONE OR COMBINED WITH OTHER HERBICIDES. J.F. Ahrens* and T.L. Mervosh, Connecticut Agricultural Experiment Station, Windsor, CT (72)


A field experiment was conducted in 2011 with mesotrione alone and in combination with other herbicides at The Connecticut Agricultural Experiment Station Valley Laboratory in Windsor, CT.  The soil type is a sandy loam with about 4% organic matter.  Six conifer species [white spruce (Picea glauca), Colorado spruce (Picea pungens), Douglas-fir (Pseudotsuga menziesii), balsam fir (Abies balsamea), Fraser fir (Abies fraseri) and white pine (Pinus strobus)] were planted between April 19 and April 21.  White pines were 3-year seedlings (3-0), and all other conifers were 4-year transplants (2-2).  Plots were 6 ft by 26 ft.  Each plot contained five plants of each species, spaced 1.5 ft apart in two rows spaced 3 ft apart.  The five herbicide treatments and the control were replicated four times in a RCBD.  Herbicides were applied with a CO2-powered backpack sprayer, equipped with four Teejet 8003VS nozzles and calibrated to deliver 30 gal / A at 28 psi.  The treatments included mesotrione 4F (Tenacity) alone at 0.187 and 0.374 lb ai / A, and mesotrione 4F at 0.187 lb ai / A plus either S-metolachlor (Pennant Magnum) at 1.91 lb ai / A, prodiamine (Barricade 65 WG) at 0.65 lb ai / A, or fluazifop-p-butyl (Fusilade DX) at 0.5 lb ai / A.  A non-ionic surfactant (Induce) was added to each treatment at 0.25% v/v.  The controls were sprayed with water plus surfactant.  Treatments were applied over active conifer growth and weeds on June 27 and again on July 26.  Weed species prevalence in each plot was rated on a scale of 1 to 3, with 1 being few, 2 being several, and 3 being many weeds, before each application.  Control of individual weeds was rated at 4 weeks after each treatment, on a scale of 0 to10, with 0 as no control and 10 as complete control.  Injury to the conifers was rated at several intervals during the season on a scale of 0 to 10, with 0 being no injury and 10 being dead plants.  Fertilizer (10-10-10) was applied at the rate of 400 lb per acre on June 1, about 6 weeks after planting.  Although 2011 was much wetter than normal, July was quite dry and we irrigated twice, applying about 0.5 inch of water each time.  The June 27 application was made on dry foliage, but on July 26 foliage of large crabgrass (Digitaria sanguinalis) was still wet with dew.  The primary goal of this experiment was to evaluate conifer tolerances during their active growth.  As a result, the weeds were mostly too large for optimal susceptibility to mesotrione, although carpetweed (Mollugo verticillata) and lambsquarters (Chenopodium album) were highly susceptible to all the treatments.  The best control of large crabgrass was with mesotrione plus fluazifop-p-butyl.  Mortality was high for some of the conifer species (even in control plots), but none of the treatments caused significant injury to any of the conifers.

FRUIT TREE TOLERANCE TO ALION™ HERBICIDE. M. Mahoney*, D. Unland, and B. DeWeese, Bayer CropScience, Oxford, MD (73)


Bayer CropScience has registered Indaziflam, trade name Alion for preemergence weed control in pome fruit, stone fruit, citrus, tree nuts and pistachios. Two years of crop tolerance studies in pome and stone fruit indicate no adverse Indaziflam effects on yield, trunk growth and shoot growth at 10 and 20 oz/acre Alion per year.

THE IR-4 PROJECT: UPDATE ON WEED CONTROL PROJECTS (FOOD USES). M. Arsenovic*, D. Kunkel, and J. Baron, Rutgers University, Princeton, NJ (74)


The IR-4 Project is a publicly funded effort to support the registration of pest control products on specialty crops.  The IR-4 Project continues to meet specialty-crop grower’s needs for weed control options despite the challenges of a mature market for herbicides and the selectivity of specialty crops to many of the more-recently-introduced herbicides.  The Pesticide Registration Improvement Act continues to effect IR-4 submissions and EPA reviews of packages. IR-4 submitted herbicide petitions to the EPA from October 2010 to October 2011 for: Sulfentrazone use on turnip, rhubarb, Wheat (PNW only), Sunflower subgroup 20B.From October 2010 through October 2011, EPA has published Notices of Filing in the Federal Register for: Clopyralid on apple, Brassica leafy greens, subgroup 5B, Rapeseed subgroup 20A, except gold of pleasure, Pendimethalin on leaf lettuce, Brassica, leafy greens, subgroup 5B, turnip greens, Melon subgroup 9A, Soybean, vegetable, succulent, Fruit, small vine climbing, except grape, subgroup 13-07E;Rimsulfuron on Caneberry subgroup 13-07A and Bushberry subgroup 13-07B; Rimsulfuron on chicory; Rimsulfuron + thifensulfuron-methyl on chicory; S-metolachlor on cilantro and garden beet leaves; Paraquat on Perennial Tropical and Sub-tropical Fruit Trees; Quizalofop-p-ethyl on sorghum (grain), and Rapeseed subgroup 20A. EPA established tolerances from October 2010 to October 2011for: Dicamba +2,4-D on teff; Fomesafen on pepper (bell and non-bell), potato, and tomato; Sulfentrazone on Vegetable, tuberous and corm, subgroup 1C, Brassica, head and stem, subgroup 5A, Brassica leafy greens, subgroup 5B, vegetable, fruiting, group 8-10, melon subgroup 9A, pea succulent, Strawberry, and flax, and Triflusulfuron-methyl on garden beet



SWEET CORN WEED CONTROL: NO-TILL, NO ATRAZINE, NO WAY? D.D. Lingenfelter*, M.J. VanGessel, B.A. Scott, and Q. Johnson, Penn State, University Park, PA (75)


Atrazine continues to be a very effective yet economical herbicide for broadleaf weed control in sweet corn, yet it is not without controversy for various reasons. Many growers have inquired about herbicide programs that allow flexibility for successional crops. Furthermore, glufosinate-resistant sweet corn varieties are expected to be registered soon, allowing over-the-top glufosinate applications and shorter crop rotation intervals. Also, as more producers are using no-till farming techniques for vegetable production, herbicide programs plays a key role in effective weed management. Research evaluating non-atrazine herbicide programs and glufosinate in no-till sweet corn is very limited.

Field studies were conducted in 2011 at two locations, Rock Springs, Pennsylvania and Georgetown, Delaware, to examine various herbicide programs in no-till sweet corn (Zea mays succharata, var. ‘BC0805’) that contain either atrazine or non-atrazine alternatives to determine their effectiveness on annual weed control. PRE and PRE fb POST programs were evaluated. PRE only treatments included: s-metolachlor + atrazine + mesotrione premix (2.47 lb ai/A); s-metolachlor + atrazine premix (2.9 lb) and pendimethalin (1.43 lb); s-metolachlor +  mesotrione premix (1.83 lb); and dimethenamid-P + saflufenacil premix (0.65 lb); whereas, s-metolachlor + atrazine premix (2.2 lb); s-metolachlor +  mesotrione premix (1.83 lb); dimethenamid-P + saflufenacil premix (0.65 lb); s-metolachlor (1.6 lb); and pyroxasulfone (0.133 lb) were applied PRE followed by a POST application of one or a combination of the following herbicides: topramezone (0.0164 lb); glufosinate (0.4 lb); atrazine (0.5 lb); foramsulfuron (0.033 lb); and 2,4-D (0.25 lb). Necessary adjuvants were included in the POST spray mixtures.  Visual weed control evaluations were taken periodically throughout the growing period.  Sweet corn yield data and crop phytotoxicity ratings were also collected (data not included).  Small-plot studies were arranged in a randomized complete block design with three replications.

At Rock Springs, evaluations just prior to the POST application revealed that PRE acetamide-only herbicide treatments provided approximately 83% control of common lambsquarters (Chenopodium album), velvetleaf (Abutilon theophrasti), smooth pigweed (Amaranthus hybridus), and ladysthumb (Polygonum persicaria); however in PRE treatments that included atrazine or an HPPD- or PPO-inhibitor, control of these same species was ≥95%. Late season ratings show that control from PRE only treatments provided 63-92% control of giant foxtail (Setaria faberi) and fall panicum (Panicum dichitomiflorum), whereas the PRE fb POST treatments increased control of these species to 90-96%. Common ragweed (Ambrosia artemisiifolia) control ranged from 78-94% and 91-97% for the PRE only and the PRE fb POST treatments, respectively. All treatments provided 89-97% control of velvetleaf and smooth pigweed. At both locations, treatments provided 91-100% control of common lambsquarters. Large crabgrass (Digitaria sanguinalis) control ranged from 58-92% for the total PRE treatments at both locations and the two-pass programs provided 92-96% control at Rock Springs and 83-97% control at Georgetown. Palmer amaranth (Amaranthus palmeri) control at Georgetown ranged from 78-100% across treatments whereas annual morningglory species (Ipomoea spp.) control was 53-87%.

In summary, atrazine does improve control of certain weed species (as is well documented through various research) and is still a very effective yet economical herbicide for broadleaf weed control in sweet corn, including no-till systems. However, depending on weed species present, reducing the rate of atrazine or eliminating it could be possible if there are concerns about carryover to rotational crops, especially vegetables, and cover crops following field or sweet corn production.  Problems with atrazine residues causing injury to rotational crops varies depending on use rates, soil types, rainfall, and other environmental conditions. However, simply replacing atrazine with another product such as an HPPD- or PPO-inhibiting herbicide will not necessarily eliminate the aforementioned concerns. Several of these types of products have stringent crop rotation restrictions as well. Once registered, glufosinate may have a good fit in sweet corn production.

SULFENTRAZONE FOR LIMA BEANS: ARE WE CHARGING FORWARD? M.J. VanGessel*, B.A. Scott, and Q. Johnson, University of Delaware, Georgetown, DE (76)


ALS-resistant smooth pigweed infestations have been documented in a number of the processing lima bean fields in Delaware.  These resistant biotypes have been very problematic to manage since broadleaf weed control options are limited.  Furthermore, infestations of Palmer amaranth have been identified in Delaware, a species prone to developing resistance.  The options for Amaranthus spp. control are either Group 2 herbicides or bentazon which is not effective for Amaranthus control.  Growers are often relying on wiper application of glyphosate to control Amaranthus species prior to harvest.  In 2011, FMC supported a 24c label for the use of sulfentrazone (Charge Charge) as a preemergence herbicide in lima beans.  A series of trials with similar treatments have been conducted in 2010 and 2011 examining lima bean safety and Amaranthus control with sulfentrazone.

 Sulfentrazone use rates in lima bean are lower rates than used for soybeans.  Two trials were conducted in 2010 and one in 2011 at the UD Research and Education Center on sandy loam soils with overhead irrigation.  Core treatments were similar for the three trials.  Treatments included sulfentrazone alone at 0.0312, 0.07, 0.094, 0.14, and 0.187 lbs ai/A, and an untreated check.  Also, two trials included sulfentrazone at 0.07 or 0.094 applied with s-metolachlor (1.5 lbs ai/A), and in 2011, s-metochalor (1.5 lbs ai/A) plus imazethapyr (0.02 lbs ai/A) was included.  Treatments were applied within 24 hrs of planting and irrigation was applied prior to lima bean emergence.  Data collected included stand counts, number of malformed seedlings, visual lima bean injury or stunting, pigweed control (smooth pigweed and Palmer amaranth), yield, and yield components.

 Lima bean injury did vary by site and evaluation date.  Lima bean injury was similar for 0.0312 to 0.09 lbs ai/A at all rating dates, except for the site in 2011when there was a significant difference between 0.07 and 0.09 lbs ai/A.  Ratings for rates of 0.09 lbs ai/A or less were ≤8% at 3 weeks after treatment.

 Parameters for stand counts, yield, and yield components were similar across the three trials.  Stand counts and number of malformed seedlings were not different for sulfentrazone treatments.  There were no differences for yield/A, number of pods per 4 plants, and number of plump, flat, and dry pods.

 Amaranthus control did not differ between sites.  There were no significant differences between 0.07 and 0.09 lbs ai/A with ratings at least 78%.  Control was similar at 3 and 5 WAT with these two rates.  Amaranthus control improved at higher rates.

 The optimum sulfentrazone rate range for weed control and crop safety on loamy sand soil is 0.07 to 0.09 lbs ai/A.  Lima bean injury increases with rates above 0.09 lbs ai/A, requiring uniform and careful application.  However, early-season lima bean injury did not significantly impact yield or yield components.



A study to assess the effects of pre-emergence herbicide combinations on wild blueberry cover, phytotoxicity, and broadleaf and grass weed cover was conducted using an RCBD design with 6 replications: a check (C), the industry standard hexazinone (2.4 lbs a.i./gal) 1 lb/a + surfactant 1 qt/a (S), terbacil 2 lb/a (T), terbacil 2 lb/a + mesotrione 6 oz/a (TM), terbacil 2 lb/a + rimsulfuron 4 oz/a (TR), terbacil 2 lb/a + linuron 2 lb/a (TL), terbacil 2 lb/a + linuron 2 lb/a + diuron 2 lb/a (TLD), terbacil 2 lb/a + hexazinone 1 lb/a + diuron 2 lb/a (THD), halosulfuron 1 oz/a (H), rimsulfuron 4 oz/a (R), and indaziflam at 5 and 10 oz/a (I). The treatments were applied on 18 May 2011 and plots were evaluated approximately 1, 2 and 3 months post-treatment.  All data were analyzed using a nonparametric median two-sample exact test with α=0.05; treatments were compared individually to C and S. In June, the TM and TL treatments had significantly higher blueberry cover than the check. In July, only TL blueberry cover was significantly higher than the C and S.  By August blueberry cover in all the T treatments was comparable to the C or S.  Phytotoxicity, observed primarily as chlorosis, was <10% in all T treatments across all evaluation times.  In June, only TLD was higher than C, and none differed from S. In July T, TLD, THD treatments had greater phyto compared to the C but, TR had significantly less compared to S.  By August no T treatment exhibited any phyto and TM and TL were not different at any evaluation.  Broadleaf weed cover was reduced in all T treatments except T vs. C in June, while all except T and TR had lower broadleaf weed cover compared to S. By July, only TLD and THD suppressed broadleaf weeds compared to C, and THD was significantly lower than S. By August, there were no longer differences in T treatments compared to C or S and only TLD and THD had lower broadleaf weed cover. T was not different at any evaluation. Grass cover was low overall in June, and only TR and THD at 0% were reduced compared to C or S.  By August, grass cover in all T treatments was significantly reduced compared to C or S except for TM which was higher than S. In June, both I treatments and H had lower blueberry cover than the C or S. In July there were no differences between I, H, or R treatments and the C or S. By August, blueberry cover in the low I treatment had declined until it was lower than S. Cover for R was not significantly different at any evaluation. The initial reduction in blueberry cover was due to significantly high levels of phyto in I and H treatments compared to the C and S, observed primarily as stunting with some chlorosis. R also showed significantly greater phyto, but was relatively minor. In July, phyto as stunting was <10% but was still significantly greater than the C or S in I and H treatments.  By August, there was no longer any observable stunting or chlorosis in any of the treatments. Both I treatments significantly suppressed broadleaf weeds compared to the C in June, and the high I treatment was also lower than S. By July, only broadleaf weed cover in the high I treatment remained lower than C or S, while H and R became higher than C and S. By August there were no differences among any of the 4 treatments and C or S but all had more broadleaf weed cover than the C. R was not significantly different at any evaluation. Grass cover in I and H treatments was significantly greater than S in June. In July, I treatments had increased in grass cover until they were significantly higher than C or S, but H was no longer different. By August, low I and H were significantly lower than S.  R was not significantly different at any evaluation.



Dodder management protocols dictate that effective applications of dichlobenil be made prior to seedling emergence.  Dichlobenil applications are typically applied in May, with most going out during the second and third week of the month.  Research has indicated that dodder has an extended germination period in cranberry; it starts typically in mid-April and may continue through June.  Dichlobenil applications made in May are likely not effective against these late-emerging populations.  There is concern, however, that applications made late in May and/or in June will cause vine injury.  Growers are reluctant to apply dichlobenil at this time of year even though dodder seedlings are continuing to germinate. The purpose of this study was to evaluate the injury and yield response of cranberry vines to dichlobenil applications made in May and June. 

In both 2009 and 2010, four distinct commercial cranberry sites in the vicinity of Wareham, MA, were selected, each planted in one of four common cranberry varieties: Ben Lear (BL), Stevens (ST), Early Black (EB) and Howes (H).  Dichlobenil was applied, using a hand-held shaker, to 1 x 2 m plots arranged in a RCBD with 5 replicates.  Treatments were made as single applications made on a weekly schedule, starting in early May and continuing to mid-June.  Growth stage assessments were made at each application date.  A high (67 kg/ha) and low (45 kg/ha) herbicide rate, typically used for dodder control, was applied at all timing intervals. 

Injury ratings were visually assessed in the year of treatment and the year following treatment.  Injury ratings were based on ease of spotting the injury (denoted by yellow vine symptoms) and by how prevalent the damage was in the plot.  Yield was collected in the year of treatment by harvesting all fruit within a randomly placed 930-cm2 quadrat. The EB site was harvested (commercially) before the fruit could be collected (2009 and 2010), so yield data are not available for EB.  Fruit were counted, assessed for any damage and weighed by the last week of October in each year.  

Ben Lear vines exhibited stress symptoms in both years and Stevens vines showed stress in one year.  No phytotoxicity was noted for Early Blacks or Howes.  Data indicate that applications made during growth spurts have the potential to cause the most injury.  In all cases, visual symptoms abated by the end of the season.  No impact on yield (weight of fruit per unit area) was detected.  Data from the present study can guide management decisions for dodder control to a limited extent.  However, longer studies are needed to fully evaluate the repetitive use of dichlobenil on cranberry vines and yield production.  Further work is also needed to document efficacy of delayed applications of dichlobenil.

THE SWALLOW-WORTS: WHERE TO NEXT? A. DiTommaso*, Cornell University, Ithaca, NY (79)


Vincetoxicum nigrum (L.) Moench. [Cynanchum louiseae Kartesz & Gandhi] (black swallow-wort) and V. rossicum (Kleopow) Barbar. [Cynanchum rossicum (Kleopow) Borhidi] (pale swallow-wort) are herbaceous perennial vines in the Apocynaceae (subfamily Asclepiadoideae) native to Europe. Both species are considered invasive in their introduced ranges in the northeastern United States and southeastern Canada, where they form dense stands, especially in high light environments such as old fields and field-woodland ecotones. These Vincetoxicum species were introduced into North America in the late 1800s, likely as ornamentals, and soon after escaped cultivation. Numerous rare and sensitive plant and animal species have been negatively impacted by these two invasives since their introduction including the monarch butterfly, Danaus plexippus L., whose natural plant host and food source the native perennial herb Asclepias syriaca (common milkweed) may be displaced from areas where the species co-occur.  The two Vincetoxicum species can also serve as population sinks for monarchs – attracting and stimulating female monarch oviposition despite their unsuitability for larval development. We have learned much about the biology, ecology, and management of these two invasive vines during the last decade of active work by several researchers in the U.S., Canada, and Europe. We currently have a much better understanding of those factors that allow for their successful establishment and spread including seedling survival, vegetative expansion, and effects of allelochemicals and competition on the resident vegetation and microbial soil community for example.  We have also learned much about managing these two invasive vines using herbicidal, cultural, and/or biological tactics.  Despite these important knowledge gains during the past decade, research on these two Vincetoxicum species needs to remain active as it is likely that the two species will continue to expand their North American range in the coming years and negatively impact susceptible ecosystems in additional regions.  

PALE AND BLACK SWALLOW-WORT GROWTH AND SURVIVAL IN NEW YORK STATE. K.M. Averill* and A. DiTommaso, Penn State, University Park, PA (80)


The invasive swallow-wort species [Vincetoxicum rossicum (Kleopow) Barbar. and V. nigrum (L.) Moench] pose challenges for land managers, as the species increase their ranges and invade new areas in the northeastern United States and southeastern Canada. Communicating current knowledge on the establishment, seasonal vegetative expansion, seasonal fecundity, and survival of swallow-wort plants will aid managers confronted with these invasive perennial vines. Data are based on demographic studies across 9 field locations in New York State, 3 of which included both old-field and forest habitats. Pale swallow-wort establishment ranged from 1.6% to 15% during 2 growing seasons following sowing. Establishment varied based on site and, to a lesser degree, on the level of pre-existing site disturbance. Survival of mature swallow-wort plants was nearly perfect (99.6 -100%) during 4 growing seasons. Mature pale swallow-wort individuals increased in number of stems per plant more rapidly in old-field habitats (60% yr-1) than in forested habitats (5% yr-1) across 3 locations and 4 years. Mature black swallow-wort individuals increased in number of stems by 42% yr-1. Pale swallow-wort fecundity in old-field habitats (130 seeds stem-1 yr-1) was generally greater than in forested habitats (45 seeds stem-1 yr-1), but was highly dependent on location. Black swallow-wort fecundity was approximately 100 seeds stem-1 yr-1 across all 3 locations. Understanding differences in swallow-wort survival, growth, and fecundity between species and across locations will provide new managers of these invasive species with baselines from which to gauge the necessary management approaches.

APPROACHES FOR SWALLOW-WORT CONTROL - DECIDING HOW TO BEGIN. N.P. Cain* and T.L. Mervosh, Cain Vegetation, Acton, ON (81)


Pale swallow-wort (PSW) [Cynanchum rossicum (Kleopov) Borhidi or Vincetoxicum rossicum (Kleopov) Barbar.], an invasive perennial in the milkweed family, has invaded many woody and herbaceous ecosystems and rights-of-way in south central and eastern Ontario and is spreading in New England.  Only one herbicide, imazapyr (Arsenal, Habitat, etc.), lists swallow-wort among weeds controlled.  PSW requires a whole-site management approach using herbicides for effective reduction of the weed.  Our objectives are to identify herbicide treatments that control PSW with minimal harm to perennial grasses, forest tree species and other plants.

Four forestry trials in southern Ontario evaluated various herbicide programs for PSW control.  The sites were a moderately-infested white pine stand in the Durham County Forest near Whitby and a heavily-infested red pine forest on Crown lands in Orono.  The Durham Forest trial compared two triclopyr (Release) and two glyphosate (Vantage Forestry) programs treated in 2008 and 2009.  A second 2009 trial, evaluated imazapyr (Arsenal) treatments compared with glyphosate.  A third trial treated in 2009 and 2010 evaluated a two-year triclopyr program.  The Orono forest trial, treated in 2009 and 2010, compared two triclopyr and two glyphosate programs with imazapyr.

           Imazapyr treatments provided one to two-season control of established PSW, depending on the level of infestation and seed bank.  Glyphosate applied twice one year and once the following year, provided excellent control of established and seedling plants.  Similarly, two applications of triclopyr provided good to fair control of PSW at the Durham site and more consistent control at Orono. 

A PSW control experiment was initiated in 2007 at a U.S. Fish and Wildlife Service refuge on Mt. Tom, near Holyoke, MA.  Herbicide treatments were sprayed over plots on June 15; some plots were sprayed again on August 29.  Treatments consisted of imazapic (Plateau), metsulfuron (Escort XP), triclopyr (Garlon 3A), triclopyr plus metsulfuron, glyphosate (Accord Concentrate), and triclopyr (June 15) plus glyphosate (August 29).  Imazapic and low dose of metsulfuron had little effect on PSW growth in 2008.  The other herbicides provided greater reduction in PSW cover and total pod weights when applied twice.  Triclopyr applied once at 1.13 lb/A ae reduced PSW pod weight by 66% and had a control rating (0 to 10) of 7.0 in August 2008; the same dose applied twice reduced pods by 87% with a control rating of 8.3.  Glyphosate applied once at 1.0 lb/A ae reduced PSW pod weight by 71% and had a control rating of 7.8; the same dose applied twice reduced pods by 97% with a control rating of 9.5. 

Single treatments of imazapyr and programs of glyphosate or triclopyr provide effective PSW control.  Triclopyr and imazapyr use is limited in forests with desirable understory species or hardwood saplings.  Triclopyr provides selective control of PSW among grasses and other monocots.  The choice of herbicide program for PSW control depends on the desirable species, the future use of the site and planting intentions. 



Pale swallow-wort (Vincetoxicum rossicum = Cynanchum rossicum) and black swallow-wort (V. nigrum = C. louiseae) are herbaceous, perennial, viny milkweeds introduced from Europe (Apocynaceae-subfamily Asclepiadoideae). Both species are becoming increasingly invasive in a variety of natural and managed habitats in the northeastern United States and southeastern Canada, especially New York State, southern New England, and Ontario. Mechanical control has been ineffective. Chemical control can be effective but expensive due to repeat applications, and non-target damage from either approach is a concern in natural areas. Biological control is considered the only long-term control option for swallow-worts. Although little to no damage by arthropods, diseases, or vertebrates has been reported to occur in North America on swallow-worts, some potentially specialized natural enemies of Vincetoxicum spp. are known from Europe. Therefore, identifying host-specific biological control agents appears promising. To date, several potential agents associated with Vincetoxicum spp. have been collected in Europe and Asia. Different species of Chrysochus leaf beetles, which possess a root-feeding larval stage, are potentially quite damaging to the plants, but based on host-range tests appear to present a risk to some native milkweeds. In contrast, defoliating moths in the genus Abrostola appear mostly specific to swallow-worts. However, swallow-wort in open fields is fairly tolerant of defoliation damage, so the moths’ efficacy is questionable. Additional natural enemies have yet to be assessed, such as the pathogen Colletotrichum lineola, a leaf anthracnose, and a seed-pod infesting fly, Euphranta connexa, and foreign surveys are continuing. The recent discovery of the pathogen Sclerotium rolfsii attacking pale swallow-wort in New York may offer potential as a bio-herbicide if it can be demonstrated that this isolate has a restricted host range. Plant demography models are being developed to identify potentially effective guilds of natural enemies, and they may indicate the need for an integrated approach to swallow-wort management.

GOATSRUE CONTROL PROGRAM IN PENNSYLVANIA. M.A. Bravo*, J. Zoschg, L. Ross, and I.D. Bowers, Pennsylvania Department of Agriculture, Harrisburg, PA (83)


Goatsrue (Galega officinalis) is a federally listed noxious weed with limited nationwide distribution. The largest site is a county in Utah, which in 1981 reported 38,000 acres (60 square miles) of infested cropland, irrigation waterways, pastures, fence lines, roadways and wet, marshy areas. Goatsrue is capable of forming a monoculture in wetland communities, displacing native or beneficial plants. Goatsrue is also fatal to most animals if ingested, particularly to sheep and cattle. In 1981 the United States Department of Agriculture (USDA) declared goatsrue a federal noxious weed and targeted it for eradication. Since then, USDA has been working cooperatively with state agencies to identify populations and limit any further spread of this federal noxious weed. The Utah State University and Utah Agricultural Experimental Station have conducted numerous studies on the biology, ecology and control of goatsrue in the United States. 

Goatsrue was discovered in Pennsylvania at six locations in 1998 as a result of the USDA surveys. Three of these locations were in McKean County and goatsrue was added to the Pennsylvania Department of Agriculture (PDA) Noxious Weed Control List in 2000.  Additional surveys in 2009 identified more goatsrue populations were emerging throughout McKean County in the vicinity of Smethport. PDA responded and began intensively surveying the county in the fall of 2009. The surge in the number of sites appears related to the dredging of the town's Hamlin Lake and the subsequent dispersement of goatsrue seed that was in the lake dredgings. It is unknown when the goatsrue was planted in the vicinity of the lake and no data has been found to suggest it was a recent occurrence. Since its discovery, the PDA has assisted property owners in the affected counties with control measures to prevent the flowering, and further spread of this noxious weed. As of 2011, less than 7,000 square feet of infested roadside ditches, meadows, and streams are known from 8 sites in Cameron, Potter and Montgomery Counties. Less than a ˝ acre has been found in Elk County, along forest roads in the Alleghany National Forest and Elk State Forest. These sites are being targeted for complete eradication.

In McKean County, approximately 43 acres of goatsrue has been discovered. The infestations can be found along roadside ditches, driveways, cropland meadows, and edges of waterways (streams, lakes, rivers) on 169 properties in 11 municipalities throughout. Thirty-six sites are state owned, 30 sites are municipality owned, 2 sites are federally owned and 101 sites are privately owned. These sites are being targeted by the PDA Noxious Weed program and partners for containment, and on a site-by-site basis, for eradication. Since the program began in the fall of 2009 at least 85% if not more of the known locations have been prevented from producing new seed once detected. In 2011, The PDA field staff extensively surveyed this counties back roads, watercourses and private lanes with few additional discoveries. Field results in 2011 indicate that once new seed production has been prevented, the surface seedbank is rapidly being depleted at these sites over consecutive years of chemical treatment. This is encouraging and landowners are confident that continued control measures will prevent further expansion- with the exception of the sites where seasonal high water scouring, due mostly to intensive periods of heavy rainfall, continues to spread seeds further in infested ditches and streams.



Pendimethalin is the current preferred herbicide for selective PRE suppression of mile-a-minute (Polygonum perfoliatum L., POLPF) in Pennsylvania state parks due to efficacy and minimal impact to established non-target species.  Pendimethalin is not effective when seed germination has occurred, and is not labeled for use in wetland settings.  An experiment was established in a floodplain at Bald Eagle State Park in Howard, PA, on April 21, 2011, to evaluate alternative treatments for selective suppression of mile-a-minute and Japanese stiltgrass (Microstegium vimineum (Trin.) A. Camus var. imberbe (Nees) Honda, MCGVM), which were both beginning to emerge.  Soil temperatures were 17, 11, and 9 C at 2.5, 7.5, and 15 cm deep, respectively.  Treatments included pendimethalin at 4.4 kg/ha, imazapic at 0.18 kg/ha alone or added to pendimethalin at 4.4 kg/ha, prodiamine at 1.6 kg/ha, or oryzalin at 4.5 kg/ha; and flumioxazin at 0.29 or 0.43 kg/ha.  A methylated seed oil surfactant was added to treatments containing imazapic or flumioxazin, at 0.5 percent, v/v.  Imazapic was added to see if it would provide enough activity to control germinated seedlings without causing injury to established plants.  Flumioxazin has contact and residual activity, and aquatic labeling.  Treatments were applied in a carrier volume of 190 L/ha to a 2.3 by 4.6 m area in a 3.8 by 4.6 m plot, leaving a 1.5 by 4.6 m untreated strip in each plot.   The plots were arranged in a randomized complete block with three replications.  Data collected included visual ratings of total cover, and POLPF and MCGVM reduction on May 24; percent total, POLPF, and MCGVM cover on July 29; and dry weight of POLPF, MCGVM, and the combination of all remaining species on August 17, 2011.  POLPF was harvested from the entire plot, and the other samples were collected from a 0.5 m2 subplot.  For each plot, data were collected separately from the treated and untreated portions.  Data were subjected to analysis of variance, and separated using Fisher’s Protected LSD.

POLPF pressure was light, averaging 3.7 g/m2 in untreated plots, and 0.1 g/m2 in treated plots.  Common non-target species were boneset (Eupatorium perfoliatum L.), goldenrod species (Solidago spp.), American burnweed (Erechtites hieraciifolius (L.) Raf. ex DC.), beggarslice (Hacklier virginiana (L.) I.M. Johnston), and several sedge (Carex spp.) species.  Suppression of MCGVM was the only significant treatment effect at the end of the season, with imazapic alone averaging 192 g/m2, pendimethalin alone 66 g/m2, and all other treatments averaging 1.6 g/m2 or less.  The primary difference between the July and August data was an apparent increase in the proportion of stiltgrass in plots treated with pendimethalin alone from July to August.

The addition of imazapic did improve suppression from pendimethalin, and in combination with prodiamine or oryzalin provided equal suppression to the pendimethalin combination.  The imazapic rate was low enough to enhance suppression from pendimethalin without causing reduction in non-target species biomass.  Flumioxazin provided excellent suppression of POLPF and MCGVM, and the contact activity was transient enough to cause no reduction in non-target or total biomass.

F9007: A NEW HERBICIDE FOR WEED CONTROL IN PASTURE AND WHEAT. J.P. Reed*, T.W. Mize, G.G. Stratman, and B.A. Neuberger, FMC, North Little Rock, AR (85)


F9007 is a new proprietary herbicide comprised of the active ingredients, carfentrazone and metsulfuron for use in pastures and wheat to control broadleaf weeds.   F9007 is formulated as a 35% dry flowable  (DF) with excellent characteristics such as practically no volatility and no grazing or haying restriction.   F9007 herbicide (aka Marshal) requires use of an Non-Ionic Surfactant  and under hotter, drier conditions a COC or MSO adjuvant has shown more country.    Research trials conducted by FMC and Universities with F9007 have shown rates in pasture, range from  1 oz F9007 product/A (0.022 lbs ai/A) to 2 oz F9007 product/A (0.044 lbs ai/A) with higher rates used for taller, larger broadleaf weeds.    In wheat, trials have demonstrated 0.4 oz F9007 product/A (0.0044 lbs ai/A) as the highest rate needed for control and excellent crop safety.   Excellent safety was observed in fescue, Bermuda grass and grass mixtures by all rates of F9007 tested in grass pastures.   No rate response by F9007 was observed in controlling Spiny Amaranth (Amaranthus spinosus), Smartweeds (Polygonum spp.), and Buttercup (Ranunculus spp.) while a slight rate response was observed in controlling Woolly Croton (Crotalaria  capitatus) and  Groundsel (Senecio spp.) and other annual broadleaves.    Rate responses by F9007 were observed in control of various thistle species providing comparable or superior control with consistently greater speed of control.    The addition of 2,4-D LVE (0.5 lbs ai/A)  enhanced control of taller Western Ragweed and Speedwell spp. (Veronica spp.) while Horsenettle (Solanum  carolinense) control was unaffected or reduced.    Semi-woody species such as Lespedeza sericea, Marshelder  (Iva annua ), Brambles ( Rubus spp), Narrow leaf Cudweed ( Gnaphium falcatum)) and Multi-Floral Rose  (Rosa multiflorium)  ) as well as vines such as Poison Ivy ( Toxicodendron radicans ), and Virgina creeper (Parthenocissus quinquefolium) are easily controlled when applications are made to newer, green woody growth up to flowering.    Last, F9007 at lower rates provided comparable or superior control of leafy spurge, while higher rates provided superior Leafy Spurge (Euphorbia esula) to standard herbicides.   

ABSORPTION AND TRANSLOCATION OF 14C-AMINOCYCLOPYRACHLOR IN THREE AQUATIC SPECIES. R.L. Roten* and R.J. Richardson, North Carolina State University, Raleigh, NC (86)


Greenhouse studies were conducted to evaluate 14C-aminocyclopyrachlor absorption and translocation in alligatorweed, water hyacinth, and water lettuce.  Alligatorweed plants were treated at the seven-node stage, water hyacinth was treated at the five-leaf stage, while water lettuce was treated at the eight-leaf stage.  All plants were oversprayed with non-labeled aminocyclopyrachlor at a rate of 0.14 kg ai/ha with 1% MSO.  14C-aminocyclopyrachlor was then applied to a protected leaf, and plants were harvested at 1, 2, 4, 12, 24, and 96 HAT.  Radioactivity was determined in the treated leaf, shoots above treated leaf, shoots below treated leaf, roots, and growing solution.  Absorption was 17 and 79% in alligatorweed at 1 and 96 HAT, respectively.  Absorption was 59% or greater at all harvest times for water hyacinth and water lettuce.  In alligatorweed at 96 HAT, 43% of absorbed 14C translocated to shoots above the treated leaf and 17% translocated to lower shoot tissue.  Water hyacinth shoots above and below the treated leaf each contained 17% of absorbed 14C at 96 HAT.  For water lettuce at 96 HAT, 53 and 36% of absorbed radioactivity was located above the treated leaf and in the growing solution, respectively.

TURION BIOLOGY OF MONOECIOUS HYDRILLA VERTICILLATA. R.J. Richardson* and S.T. Hoyle, North Carolina State Univ., Raleigh, NC (87)


Since the discovery of Hydrilla verticillata in the United States, much research has been conducted to find weaknesses in its life cycle. Most of this work has been done on the dioecious form, which has historically been the most prevalent and problematic. However, the monoecious form is rapidly expanding in range and significant differences may exist in the biology of the two biotypes. Recent research at North Carolina State University into the dynamics of monoecious hydrilla tuber sprouting has revealed interesting, and sometimes surprising results. Growth chamber trials have indicated similarities in sprouting of both biotypes under temperature and light manipulation. Research has also been conducted to determine the effect on tuber sprouting under exposure to a range of pH, salinity, or herbicides. Tubers sprouted in solutions with pH between 4.0 and 10.0 with few differences in initial growth. Tubers exposed to a salinity level of 24 part per thousand for 2 weeks sprouted when placed into a solution of deionized water, but did not sprout under constant salinity exposure. It was also observed that monoecious hydrilla tubers have multiple axillary buds preformed within dormant tubers that are capable of producing secondary shoots even when the terminal shoot is removed. These findings can help refine management plans to best exploit weaknesses in the biology of monoecious hydrilla.



Few crops can be grown without some form of direct weed control, usually seedling-focused, and usually achieved with application of herbicide, or cultivation.  Where seedling density is low, and efficacy is high, competition from a well-managed crop will minimize yield loss, weed biomass and seed rain.  This simple approach to weed management begins to fail, however, when efficacy is reduced, as is often the case for cultivation, or with herbicide resistant weeds.  One solution is to focus efforts on new or alternative cultivation or herbicide options with a high level of efficacy.  Another approach aims to exploit multiple stresses on weed populations to reduce seedling density and thus the requisite efficacy for herbicide or cultivation events. 

The view that “Many Little Hammers” can impose stresses at multiple life-history stages of weeds and thereby reduce the burden of weed management placed on seedling control is increasingly accepted in the organic farming community.  Organic farmers are often diverse and they share a philosophy that places soil quality as a priority area for management.  Soil-improving management in particular adds diversification and opportunity to reduce the weed seedbank, multiple benefits that farmers value.

  Our cover cropping component and systems experiments over the past ten years have included research on allelopathy or residue effects on seedling establishment, weed seed predation, weed/crop interference, weed seed rain, and seedbank dynamics.  Cover crop diversification generally affects these processes in ways that benefit weed management efforts, but particular practices can result in high levels of weed seed rain.  Organic farmers frequently cite crop rotation and cover cropping as important weed management practices, after cultivation.  However, observation and on-farm weed seedbank data demonstrate that these practices do not guarantee successful weed management.  Clearly, it is not diversification, but rather management that drives weed dynamics, and in this regard, context may be everything.  Where weed seedbank densities are low, moderate cultivation efficacy, crop competition, seed predation, and perhaps green manuring to reduce the abundance of safe-sites, may result in acceptable weed control.  However, these same practices, lacking positive density-dependent effects, will likely fail where an initial seedbank is extremely high.  In this situation, successful weed management requires practices that deplete the seedbank and preempt seed rain.  Simulation models and case studies of successful organic farmers support this conceptual framework that efficacy of multiple stresses should be considered over a range of realistic weed densities.




There are many reasons why farmers are not utilizing more integrated weed management (IWM) practices. These reasons can be traced to many factors that ultimately influence the grower’s decision to incorporate various weed management options into a cropping system.  Farmer’s decisions are not only influenced by their own beliefs and circumstances but also ag service providers, regulatory agency rules, academic recommendations, and societal leanings. These perspectives often conflict and limit the adoption on IWM techniques in Northeastern cropping systems. Some of these forces are based on traditions or ideologies, while others are driven by larger factors outside the producer’s control. Certain clashes or misunderstandings could possibly be overcome with communication and education but other elements are more difficult to manage since economics, government policy, personal beliefs and individual circumstances, and agronomic factors are all entwined. As agriculturalists we need to start asking some questions to better direct the stewardship of our weed management resources. For example: “What currently drives IWM?”; “What are farmer’s doing now and what limits them from using more IWM?”; “How are companies marketing herbicides and seed traits to encourage (or discourage) product stewardship/longevity and IWM tactics?”; and “Are government programs helping or hindering this process?”  These and other questions need to discussed and addressed if we are to better deal with the dynamic nature of weeds with more integrated approaches.

IWM: WHAT THE HELL IS THAT? J. Lindquist*, University of Nebraska, Lincoln, NE (90)


Integrated Weed Management has been defined in many ways and many times. I’m not about to redefine it. However, I will talk about the core principles of IWM and describe how some of my research is relevant to IWM.



Integrated weed management (IWM) calls for the use of multiple practices, but determining which practices to combine is not entirely clear. Combining some practices can result in antagonistic effects, whereas others can interact synergistically. Although there is a rich body of literature on testing for synergism and antagonism between herbicides, relatively little attention has been given to developing systematic tests of multiple cultural, physical, and/or biological weed management practices. We introduce a straightforward protocol for systematically testing the combined effects of non-chemical weed management practices. This protocol is illustrated using data collected from an experiment that tested the effect of crop planting rate and winter rye mulch amount in no-till planted soybean. Increasing mulch and planting rate resulted in a synergistic interaction between practices, defined as a statistically significant, positive deviation from a multiplicative reference model. We speculate the increased mulch delayed weed seed germination, allowing soybean, which has a relatively large seed, to emerge, form a competitive canopy, and effectively preempt weeds. In addition to management practices whose effects act simultaneously, interactions between practices applied sequentially also have important implications for IWM. Empirically testing the effects of sequences of practices applied to different cohorts of weeds at different life stages can be challenging and has generally been done by modeling population dynamics. Because some weed management practices can be density dependent (i.e., efficacy is greater at lower densities), previously applied practices can affect the efficacy of subsequent practices. Although not necessarily a synergistic interaction, such interactions between density dependent practices are important and deserve recognition. Harnessing synergistic interactions between practices applied simultaneously and strategic sequences of practices that result in effective non-chemical weed control is a promising solution to weed management challenges associated with herbicide resistance and organic cropping systems. Future research should aim to develop methods and approaches to testing the weed-crop competition, population, and community level effects of interactions between cultural, physical, and biological management practices. 




Integrated weed management has been advocated by the weed science community for over 20 years yet there appears to be little adoption. The objective of this talk is to highlight research recent results from our IWM studies in our lab and explore reasons why the perceived adoption of IWM has been low.  Organic weed management is inherently difficult because of the prohibition of synthetic herbicides. Because of this, organic farmers rely mostly on cultural and mechanical weed control. We have found that by combining increased seeding rates, competitive crop cultivars and in-crop harrowing in organic oat that we have been able to reduce weed biomass by 70% compared to standard agronomy. In a current study, we are investigating the utility of “organic” weed control benefits for controlling imadazoline resistant broadleaf weeds in lentils. I believe that most people seek simplicity in life. Therefore, the expectations of weed scientists that farmers should increase the complexity of their weed control regime proactively may be unreasonable.



Weeds remain a perennial challenge to agricultural productivity despite decades of advancement in weed control practices intended to eliminate weeds.  This paradox is in large part a consequence of our cropping practices, which effectively maintain cropping systems in a state of very early succession.  As early successional plants, weeds are adapted to take advantage of the weed-promoting conditions that our cropping practices create, namely an abundance of resources and space.  While integrated weed management (IWM) programs often focus on the use of multiple control tactics aimed at diversifying the selection pressures that act on existing weed populations, an equally important, yet often overlooked principle of IWM is to address the factors that make cropping systems susceptible to weeds and their impacts in the first place.  Understanding the ecological basis for why weeds are present and problematic in our cropping systems, and then explicitly addressing these factors through consideration of successional processes, may provide opportunities for the development and adoption of more robust IWM programs.  The most robust of these programs are likely to include integrated management practices that promote or mimic the characteristics of later successional plant communities.



Methiozolin is a new cellulose biosynthesis inhibitor being evaluated for selective control of annual bluegrass (Poa annua L.) in creeping bentgrass (Agrostis stolonifera L). Research was initiated in 2010 evaluating the efficacy of single and sequential methiozolin programs for annual bluegrass control.

Research was conducted at Lambert Acres Golf Course (Alcoa, TN) on ‘Penncross’ creeping bentgrass green naturally infested with annual bluegrass. Turf was established as a native soil pushup green. Turf was mowed daily at 3 mm and irrigated to promote optimum creeping bentgrass growth.  Fertility was applied at 4.9 kg N ha-1 per week using a complete fertilizer (18N: 3P2O5: 6K2O). Applications of triticonazole, chlorothalonil, fosetyl-al, iprodione, and mefenoxam were applied on as-needed basis at labeled rates.

Methiozolin was applied singly and sequentially at 0.5 and 1 kg ha-1 at three fall timings: October, November, and December. Programs of two and three sequential methiozolin applications (applied on a three-week interval) were evaluated at each timing and compared to a sequential application program (three week interval) of paclobutrazol at 0.28 kg ha-1 initiated in October. Experimental design was a randomized complete block with three replications. All treatments were applied using a CO2 powered boom sprayer calibrated to deliver 30 gpa using four, flat-fan, 8002 nozzles at 18 psi, configured to provide a 1-m spray swath. Creeping bentgrass injury was rated on a 0 (no turf injury) to 100% (complete kill of all turf) scale relative to an untreated control throughout the fall and winter of 2010. Annual bluegrass control was rated on a 0 (no control) to 100% (complete kill) scale in the spring of 2011. Annual bluegrass plant counts were made 25 weeks after initial treatment (WAIT) using a 1-m by 1-m grid with 100 intersection points.

Applications of MRC-01 effectively controlled annual bluegrass in this study. Annual bluegrass control increased throughout the spring with control ranging from 73 to 100% by 25 WAIT. With the exception of a single application in October, annual bluegrass control 25 WAIT with methiozolin at 1 kg ha-1 exceeded 90% regardless of application frequency. All MRC-01 treatments controlled annual bluegrass greater than paclobutrazol at 25 WAIT as well. By 28 WAIT, all sequential methiozolin programs at 1 kg ha-1 reduced annual bluegrass plant counts > 90% compared to 49% for paclobutrazol. Results suggest that MRC-01 is highly efficacious for annual bluegrass control in creeping bentgrass putting greens in Tennessee. However, additional research is needed to evaluate programs involving both fall and spring applications on sand and soil-based rootzones.




Methiozolin (MRC-01) is a new herbicide under development by Moghu Research Center of South Korea for use on golf putting greens in the US and other countries.  Previous research has shown that annual bluegrass control increased when methiozolin was applied in fall compared to spring or early summer treatments.  Fall treatments work well in southern climates where annual bluegrass populations are typically less than 15% coverage and perennial biotypes are most commonly encountered.  In the north, annual bluegrass populations on putting greens can exceed 70% and have a higher proportion of annual biotypes.  Annual biotypes are easier to kill and fall treatments in the north may result in rapid control of large annual bluegrass populations, resulting in thin turf or bare areas on the putting green the following spring.  In addition, creeping bentgrass does not have opportunity to fill voided areas of turf during the winter.  Since spring and early summer is the time when most golf revenue is generated in the Northeast, loss of putting green canopy is unacceptable during this time.  Since spring treatments are known to be less effective at controlling annual bluegrass, we hypothesized that repeated treatments in spring will result in a slower, smoother transition from annual bluegrass to creeping bentgrass.  Our objective was to evaluate several treatment programs that included 4 kg ai/ha methiozolin split into 4, 6, or 8 treatments during spring and early summer compared to a program that included two high-rate spring applications followed by an additional application in fall.

Two studies were conducted on golf courses in Blacksburg and Harrisonburg, VA.  Studies were arranged in randomized complete block designs with 3 replications.  Plots were 2 m by 2 m in Blacksburg and 2 m by 5 m in Harrisonburg.  The larger plots in Harrisonburg allowed for measurement of ball speed (stimp).  Treatments were initiated on March 4, 2011 at Harrisonburg and March 20, 2011 at Blacksburg.  Methiozolin was applied in 280 L/ha water using TeeJet 11004 TTI nozzles.  Treatments included 8 applications of 500 g/ha at 2 wk intervals, 6 applications of 667 g/ha at 2 wk intervals, 4 applications of 1000 g/ha at 4 wk intervals, and 3 applications of 1120 g/ha in March, April, and October.  On June 15, 2011, Methiozolin applied 8, 6, or 4 times in spring reduced annual bluegrass cover from 58% in nontreated plots to 2, 1, and 5%, respectively.  The spring + fall program had received two of three treatments at this time and reduced annual bluegrass cover to 15%.  Similar reduction in annual bluegrass cover was noted in Blacksburg.  On June 3, 2011 in Harrisonburg, stimp on nontreated plots was 8.4 feet and significantly higher (9.5 to 10.0 feet) in methiozolin treated plots.  Methiozolin did not injure creeping bentgrass at any assessment date.  Putting green turf quality and NDVI was significantly lower than nontreated turf in April but equivalent in March, May, June, July, and October.  The loss of NDVI and quality in April was attributed to loss of annual bluegrass vigor.  The greatest loss of turf quality from methiozolin treatment was on April 28 when nontreated plots had quality of 6.5 and the worst methiozolin treatment had quality of 5.83, where 6.0 is minimally acceptable.  Such transient loss of quality was actually deemed acceptable by golf course personnel due to the reduction in annual bluegrass.  Turf quality was significantly higher in methiozolin-treated plots from May through October.  NDVI was equivalent in all plots from June through October.  These data suggest spring programs can successfully control annual bluegrass while having minimal impact on putting green quality on golf putting greens having greater than 50% annual bluegrass infestation.



Field studies were conducted in Virginia and New Jersey from 2010 to 2011 to evaluate the use of methiozolin for annual bluegrass control in creeping bentgrass putting greens. In Virginia, non-replicated demonstrations were established on four different putting greens at two golf courses. At Spotswood Country Club (CC), three strips (2m by 25m) were treated with methiozolin at 0.75, 1.5, and 3.0 kg ai/ha on March 18, April 15, and Oct 20, 2011.  At Lakeview CC, three different putting greens were treated with methiozolin at 1.0 kg/ha on April 15, May 13, and Oct 20, 2011.  Initial annual bluegrass populations were 40 to 60% cover at all locations.  When assessed in November 2011, annual bluegrass cover reduction was 20, 75, and 95% in plots treated with 0.75, 1.5, and 3.0 kg/ha methiozolin, respectively.  At Lakeview, annual bluegrass cover reduction was 90, 60, and 30% on the three test sites. In New Jersey, studies were established in the fall of 2010 at Riverton, Metedeconk, and Charleston Springs CC. Methiozolin treatment regimes were 0.5, 1.0 and 2.0 kg/ha applied twice in Sept/Oct, Oct/Nov, and once in Nov. Methiozolin at 0.5 and 1.0 kg/ha was also applied three times in Sept/Oct/Nov. Annual bluegrass populations were high at Riverton (> 50%), low at Charleston Springs (<10%) and initially low at Metedeconk. However, by late fall plots at Metedeconk averaged 30 to 40% annual bluegrass cover. Creeping bentgrass injury was not evident until the following March at all three locations.  At Charleston Springs, creeping bentgrass injury was 33 and 24% when methiozolin was applied at 2.0 kg/ha in Oct/Nov and Sept/Oct, respectively, but less than 10% with all other treatments. However, in late March creeping bentgrass injury increased to 65 and 30% with these two treatments. In addition, injury with all other treatments increased to 9 to 30%. At Metedeconck, creeping bentgrass injury was most evident in late March with 60 and 80% injury observed when methiozolin was applied at 2.0 kg/ha in Sept/Oct and Oct/Nov, respectively. Injury with other treatments ranged from 10 to 60%. At both locations, creeping bentgrass recovered rapidly with 30% injury or less with all treatments in early May. Many treatments which had shown noticeable injury in late March had completely recovered by early May. Annual bluegrass control was 85% or greater at both locations when methiozolin was applied at 1.0 kg/ha or greater regardless of application timing. Similar results were observed at Riverton CC when methiozolin was applied at 1.0 kg/ha or greater. These studies suggest that methiozolin can effectively reduce annual bluegrass populations dramatically when applied in the fall. However, additional research needs to be conducted to balance annual bluegrass control while limiting creeping bentgrass injury.

SEEDHEAD SUPPRESSION OF AN ANNUAL BLUEGRASS PUTTING GREEN. J. Borger*, M.B. Naedel, and K.R. Hivner, Penn State University, University Park, PA (97)




J. A. Borger, M. B. Naedel, and K. R. Hivner1




            Three separate annual bluegrass (Poa annua) seedhead suppression studies were conducted using various materials and application timings.  The first two studies, in 2009 and 2010, were conducted on a mature monostand of annual bluegrass at the Valentine Turfgrass Research Center, Penn State University, University Park, PA. The third study, conducted in 2011, was conducted on a ‘Pencross’ creeping bentgrass (Agrostis stolonifera) and annual bluegrass putting green at the Pennsylvania State University Blue Golf Course, University Park, PA.  The objective of the studies was to determine if selected materials could suppress seedhead formation of annual bluegrass under simulated golf course greens conditions.  All trials were randomized complete block designs with three replications each.  For the first study, treatments were applied on April 1 (EARLY), April 13 (BT), and May 6, 2009 (3 WABT).  For the second study, treatments were applied April 2 (EARLY), April 20 (BT), and May 5, 2010 (3 WABT).  For the third study, treatments were applied April 7 (EARLY), April 21 (BT), and May 12, 2011 (3 WABT). Treatments for all three trials were applied using a three foot CO2 powered boom sprayer calibrated to deliver 80 gpa using one, flat fan, TP9508EVS nozzle at 40 psi.  The test areas at the Valentine Turfgrass research Center were maintained at 0.125 inch using a Toro triplex reel mower.  The test area at the Penn State Blue Golf Course was maintained at 0.140 inch using a Jacobsen walking reel mower.  Additionally, turfgrass was irrigated on an as needed basis to prevent moisture stress at both test sites.  The test sites consisted of approximately 65 percent annual bluegrass seedhead cover in the untreated test plots at the times of data collection.  Annual bluegrass seedhead cover was visually evaluated on May 6, 2009, May 17, 2010, and May 16, 2011, on a plot by plot basis.  Data for these studies were then transformed into a percent suppression value via an Abbott’s Transformation using Agricultural Research Manager software.  In the first study, Primo Maxx at 0.125 oz/M plus Proxy at 5 oz/M were evaluated alone or in combination with ProGibb T&O at 0.06 g ai/A at various timings.  All treated turfgrass revealed a significant level of seedhead suppression compared to that of untreated turfgrass, with the exception of Primo Maxx plus Proxy with a single application timed at boot stage (BT).  Turfgrass treated with Primo Maxx, Proxy, and ProGibb T&O applied EARLY and BT revealed significantly higher seedhead suppression than turfgrass treated with Primo Maxx plus Proxy applied once at BT.  In the second study, Primo Maxx at 0.125 oz/M plus Proxy at 5 oz/M were evaluated alone or in combination with ProGibb T&O at 0.06 g ai/A at various timings.  All treated turfgrass with the exception of ProGibb T&O at 0.06 g ai/A applied alone at any timing (except the EARLY timing) and Primo Maxx plus Proxy plus ProGibb T&O applied EARLY, did not significantly reduce the presence of annual bluegrass seedheads.  Notable results of this trial include a significant increase in seedhead suppression when Primo Maxx, Proxy, and ProGibb T&O were combined compared to Primo Maxx plus Proxy without ProGibb T&O applied EARLY or in succession (EARLY, BT). However, when these treatments were compared to one another with three total applications (EARLY, BT, and 3 WABT), no significant differences were found.  In the third study, Primo Maxx at 0.125 oz/M plus Proxy at 5 oz/M were evaluated alone or in combination with ProGibb T&O at 0.06 g ai/A at various timings.  All treated turfgrass, with the exception of ProGibb T&O applied alone three times (EARLY, BT, and 3 WABT), revealed a significant reduction of annual bluegrass seedhead cover when compared to untreated turfgrass.  When ProGibb T&O was added to Primo Maxx plus Proxy applied three times, a significant increase in annual bluegrass seedhead suppression was observed.  More research will continue to be conducted to investigate issues regarding the addition of gibberillic acid into annual bluegrass seedhead suppression strategies for golf course putting greens.



1 Instructor, Research Technician II, and Research Technician I, Respectively, Department of Crop and Soil Sciences, Penn State University, University Park, Pa, 16802



Extension bulletins and turf herbicide labels often recommend not to mow turf 24 hours before or after application of a herbicide to maximize weed control. However, the effect of mowing on herbicide efficacy has not been sufficiently explored. The ability to make a herbicide application soon after mowing or prior to mowing would give turf managers more flexibility in scheduling applications and help lawn care operators who often make herbicide applications to lawns but do not have control of the mowing schedule for these properties. The objectives and this research were to 1) determine which herbicides most effectively control ground ivy (Glechoma hederacea), 2) determine the effects of mowing on ground ivy control, and 3) determine if any herbicide by mowing timing interactions exist. The experiment was arranged as a 3 X 6 factorial with main effects of mowing timing and herbicide selection. Individual plot size was 2.25 m2. Three mowing timings included mowing 30 minutes before application, mowing 30 minutes after application, and no mowing 72 hours before or after application. These mowing treatments were designed to simulate a worst case scenario of mowing either immediately prior to or after a mowing. Plots were mown at 5 cm removing 1.3 to 3.8 cm of Kentucky bluegrass (Poa pratensis) leaf tissue. Ground ivy was dispersed through the turf canopy at heights of 1.3 to 7.6 cm prior to mowing and the mowing treatments removed approximately 30-40% of the ground ivy leaf tissue. The seven herbicide treatments were 2,4-D ester at 3.2 kg ae/ha; metsulfuron at 0.02 kg/ha; aminocyclopyraclor at 0.08 kg ae/ha; 2,4-D + mecoprop + dicamba; triclopyr at 1.12 kg ae/ha, and the untreated check. The herbicide was mostly dry on the leaf surface when mowing 30 minutes following an application; however, the deck of the mower was cleaned with a blower to remove debris after each plot was mown to reduce the potential to track herbicide from one plot to another. Plots were treated with herbicide 29 October 2010. Herbicides were applied in 814 L/ha water with a CO2-pressurized sprayer at 207 kPa. Ground ivy coverage was visually rated. All data were analyzed using SAS (SAS Institute, Inc). The data were analyzed as a 3 X 5 Factorial without the untreated check. Means were separated using Fisher’s protected least significant difference when F tests were significant at α=0.05. When rated 17 November (3 weeks after application) there were no immediate visible effects of the herbicide treatments. However, on each spring rating date there was a significant effect of the herbicide. When rated on 8 July 2011, the 29 October 2010 application of aminocyclopyrachlor reduced ground ivy coverage most. The excellent control of ground ivy from aminocyclopyrachlor was consistent with other research done at this location. At no point in the experiment did the main effect of mowing have a significant impact on ground ivy coverage nor was there a significant mowing by herbicide interaction. Thus, this preliminary data suggests that whether or not turf is mown before or after an application may not be as important as previously thought for controlling broadleaf weeds. This experiment will be repeated in 2011-2012.



Public pressure to ban or limit synthetic pesticide use on turfgrass has greatly increased the past few years.  Very little research has been published or presented concerning alternatives to synthetic herbicides for broadleaf weed control in turfgrass.  A 3-year study was conducted to evaluate broadleaf weed control in turfgrass using various alternatives to synthetic herbicides.

In September 2009, 11 treatments were applied to a lawn area in Doylestown, PA that contained about 20% broadleaf weeds and 80% cool-season turfgrasses.  Treatments included hand-pull, Burnout II (citric acid, clove oil, sodium lauryl sulfate), Weed-A-Tak (clove oil, phenethyl propionate, corn gluten meal), household vinegar, compost, corn gluten meal, glyphosate, synthetic herbicide (2,4-D, MCPP & dicamba), Burnout II/seed perennial ryegrass, an experimental organic extract, and an untreated control.  Treatments that were liquids were applied as spot treatments for the weeds using a hand-pump spray bottle and were re-applied 7 days after initial application to any remaining weeds.  On adjacent sites, the study was repeated in September 2010 and September 2011 with 4 additional treatments— FeHEDTA, propane torching, ammoniated soap of fatty acids, and sodium tetraborate.  Weeds were spot-treated 0 and 14 days after initial treatment (DAIT) for all treatments except corn gluten meal and compost which were blanket treatments. 

Percent weed cover by weed species was evaluated approximately every 7 DAIT for 70 days.  Since each weed species did not always appear in each plot, percent weed cover by species were combined for each plot.  Statistical analysis was conducted on total percent weed cover data since treatments had similar percent weed cover at 0 DAIT.  Total percent weed cover data were subjected to the square root transformation to stabilize variance and then subjected to ANOVA with means separated with Tukey’s HSD.  Untreated control plots were included in statistical analysis.  Turf quality was assessed visually according to NTEP standard practices where 9 was outstanding or ideal turf and 1 was the poorest or dead turf.  A rating of 6 or greater was considered acceptable.

Most treatments significantly reduced percent weed cover, however some of these treatments (Burnout II, Weed-A-Tak, glyphosate, vinegar, organic extract, ammoniated soap of fatty acids) killed turfgrass as well and resulted in very poor turf quality.  Hand-pull, FeHEDTA, and the synthetic herbicide treatments killed the weeds without decreasing turf quality.  Some treatments (hand-pull, Burnout II, Weed-A-Tak, glyphosate, FeHEDTA, ammoniated soap of fatty acids, organic extract) controlled weeds as well as the synthetic herbicide.  Various treatments needed multiple applications since the initial application caused only leaf necrosis and the weed resurged.  The corn gluten meal and compost treatments did not significantly control weeds compared to the untreated control. The corn gluten meal significantly improved turf quality, however, growth was excessive.



In the past 15 years, environmental genomics-based research has advanced new developments in the biomedical and manufacturing industries, but few products have been developed for agricultural and landscape management. Environmental genomics provides a new set of tools for the discovery of compounds that suppress weeds or enhance target plant growth. Direct genomic extraction from natural environments and complex communities into clone libraries allows researchers to screen for biosynthetic herbicides or growth-enhancing bioinoculants. I will be discussing examples of screening methods to isolate genes and gene clusters captured in clone libraries expressing the production of biosynthetic compounds relevant to weed management. Further isolation of the biosynthetic compounds in cell-free suspensions can elucidate the potential of the compounds as active ingredients in herbicides. Environmental genomics may provide a cost-efficient alternative to the development of new synthetic herbicides, as the cost of synthetic pesticide development continues to rise.   



Annual bluegrass comprises a large portion of putting green turf in the Northeast.  Failed attempts to control this weed have led to its adoption as part of the playing surface and cultural practices have been adapted to improve putting conditions in a mixed creeping bentgrass and annual bluegrass turf.  One such practice is the use of plant growth regulators such as mefluidide and ethephon for suppressing annual bluegrass seedheads in spring.  The two most common programs include application of mefluidide plus foliar iron or ethephon plus trinexapac ethyl when growing degree days at base 50 (GDD50) reach 50 units.  These programs are notoriously inconsistent for annual bluegrass seedhead suppression.  Suppression varies each year and ranges from 20% to 95% for ethephon and 40% to 95% for mefluidide.  Attempts to reduce application frequency or increase the number of spring applications have led to turfgrass injury.  Close observation of annual bluegrass on golf putting greens in early spring will show that many plants have already initiated seedhead production before 50 GDD50.  Some plants have been observed to produce an occasional seedhead under snow.  We hypothesized that inconsistency in seedhead suppression over years is largely due to variable amounts of annual bluegrass plants that initiate seedhead production during winter, driven primarily by periodic warm winter temperatures or thermal heating under snow.  Our objective was to determine if applications made in late winter could improve annual bluegrass seedhead suppression from standard ethephon or mefluidide programs compared to these programs without the early treatment.  We also included demethylation inhibiting fungicides (DMI) in some treatments to determine if several combined components of the program might accumulate and lead to turfgrass injury if mixed with use of a plant growth regulating fungicide.  Two field trials were conducted on putting greens mown at 3 mm.  One trial was in Blacksburg, VA and the other was in Harrisonburg, VA.  Treatments were arranged in a randomized complete block design with three replications.  The "early" application was applied on March 4 and the putting green was still brown from winter stress.  The normal program application dates were April 15 applied at 48 GDD50 and four weeks later.  On April 28, annual bluegrass seedhead coverage was 47% in the nontreated check and equivalent in the ethephon early treatment, ethephon normal program, and with a single treatment of triadimefon.  When the ethephon early treatment was combined with the normal program, however, seedhead coverage was reduced to 0 to 7%.  The early treatment of mefluidide reduced seedhead coverage to 20% and all normal programs of mefluidide either alone, with the early treatment, or with the early treatment and triadimefon completely eliminated seedhead production.  Similar trends occurred on May13th; however, on May 26th, all normal program treatments regardless of early treatment or DMI fungicide completely controlled annual bluegrass seedheads, presumably because the second normal program treatment had been applied prior to this rating.  Early treatments and/or triadimefon did not increase turfgrass injury compared to normal mefluidide or ethephon programs alone; however, the normal program of mefluidide injured turf 30 to 60% and significantly decreased normalized difference vegetative index (NDVI) from April 15 to May 13 while ethephon did not cause injury or decrease NDVI.  These data suggest an early application of seedhead inhibitors can improve annual bluegrass seedhead suppression when applied prior to a normal GDD50-timed program, especially in the case of ethephon.

TALL FESCUE (FESTUCA ARUNDINACEA) TOLERANCE TO SPRING AND FALL AMICARBAZONE APPLICATIONS. G.K. Breeden*, J.T. Brosnan, and P. McCullough, University of Tennessee, Knoxville, TN (102)


Amicarbazone is a new photosystem II inhibitor being evaluated for use in cool-season turfgrass. Data describing cool-season turfgrass tolerance to amicarbazone are limited. Research was conducted from 2010 to 2011 evaluating tall fescue (Festuca arundinacea) tolerance to spring and fall to applications of amicarbazone. 

Separate trials were conducted to determine tolerance to spring and fall amicarbazone applications. The site for each trial was a mature stand of ‘Coyote II’ tall fescue maintained as a golf course rough at the East Tennessee Research and Education Center-Plant Sciences Unit (Knoxville, TN).  Plots (1.5 by 3 m) were arranged in a randomized complete block design with three replications. Amicarbazone (98 g ha-1, 196 g ha-1 and 392 g ha-1) and bispyribac-sodium (111 g ha-1) were applied sequentially on a two-week interval. An untreated control was included for comparison. Four application timings were evaluated in the fall trial: September, October, November, and December. The same treatments were applied in the spring trial in March and April. All herbicides were applied with a CO2 powered boom sprayer calibrated to deliver 280.5 L ha-1 utilizing four, flat-fan, 8002 nozzles at 124 kPa, configured to provide a 1.5-m spray swath. Tall fescue injury was evaluated visually utilizing a 0 (no turf injury) to 100% (complete kill) scale at 7, 14, 28 49, 62, 91, and 144 days after initial treatment (DAIT).

Injury present 21 DAIT with amicarbazone at ≥196 g ha-1 ranged from 40 to 92% for treatments in September and October. By 66 DAIT, tall fescue injury with these treatments was >40%. Applied in November and December, these treatments induced 20 to 60% injury 21 DAIT. Applications of amicarbazone at 98 g ha-1 in November injured tall fescue from 0 to 36% at 21 DAIT. By 144 DAIT, amicarbazone at < 196 g ha-1 in September, October, and November injured tall fescue ≤ 8%. At 392 g ha-1 these treatments injured tall fescue ≥ 85% at 144 DAIT. Bispyribac-sodium applied at all fall timings injured tall fescue ≤ 42% at 28 DAIT. By 62 DAIT, bispyribac-sodium in September and December injured tall fescue ≤ 3%, while October and November applications injured tall fescue ≤ 38%.

Spring applications were less injurious to tall fescue as no injury was observed with amicarbazone at 98 and 196 g ha-1 in March. Amicarbazone at 392 g ha-1 in March injured tall fescue 25% by 49 DAIT, but declined to 0% by 91 DAIT. Injury with April applications of amicarbazone at ≤ 196 g ha-1 ranged from 0 to 12%, with no injury present 21 days after application. Amicarbazone at 392 g ha-1 in April injured tall fescue 50% by 28 DAIT. By 62 DAIT injury had decreased to ≤ 23%. Comparatively, bispyribac-sodium at all spring application timings injured tall fescue ≤ 25% through the end of the study. These data suggest that fall applications of amicarbazone should be avoided on tall fescue, while spring amicarbazone applications at ≤ 196 g ha-1do not result in significant tall fescue injury.


MESOTRIONE AND AMICARBAZONE COMBINATIONS FOR ANNUAL BLUEGRASS (POA ANNUA) CONTROL. M.T. Elmore*, J.T. Brosnan, and G.K. Breeden, University of Tennessee, Knoxville, TN (103)


Mesotrione efficacy for annual bluegrass (Poa annua) control can be inconsistent. Amicarbazone is a photosystem II-inhibiting herbicide with activity against annual bluegrass. Field and greenhouse experiments were initiated in 2011 at the University of Tennessee evaluating the efficacy of mesotrione and amicarbazone for annual bluegrass control.

Annual bluegrass was collected from the East Tennessee Research and Education Center (Knoxville, TN). Single tillers were transplanted to cone-tainers filled with Sequatchie silt-loam soil. Plants were allowed to acclimate for 4 weeks and contained 5 to 7 tillers when treatments were applied. Nitrogen was soil-applied at 49 kg ha-1 (46N:0P:0K) prior to treatment application. Treatments were arranged in a 2-by-2 factorial, completely randomized, design with ten replications. Treatments consisted of mesotrione (280 g ha-1) or topramezone (14.5 g ha-1) applied with amicarbazone (0 and 79 g ha-1). An untreated-control was included for comparison. Herbicide treatments were applied singly with a nonionic surfactant (NIS) at 0.25% v/v and 340 L ha-1 water using a spray chamber. Two experimental runs were conducted in 2011. Annual bluegrass control was evaluated visually on a 0 (no control) to 100% (complete control) scale and using chlorophyll fluorescence yield (Fv/Fm) at 3, 5, 7, 14 and 21 days after treatment (DAT). Aboveground dry biomass was measured 21 DAT.

Field experiments were conducted on a dormant bermudagrass (Cynodon dactylon) fairway overseeded with perennial ryegrass (Lolium perenne) at 440 kg ha-1. Treatments were arranged in 2-by-4 factorial, randomized complete block, design with three replications. Treatments consisted of mesotrione (280 g ha-1) or topramezone (14.5 g ha-1) applied with amicarbazone (0, 79, 160 or 240 g ha-1). An untreated-control, bispyribac-sodium (78 g ha-1) and methiozolin (1.5 kg ha-1) were included for comparison. All herbicide treatments were applied singly with NIS at 0.25% v/v and 280 L ha-1 of water using small-plot spray equipment. Treatment responses were evaluated visually from 7 to 56 DAT. Grid counts were conducted 56 DAT as well.

In greenhouse experiments, amicarbazone alone provided < 5% annual bluegrass control on all rating dates. By 21 DAT, mesotrione only controlled annual bluegrass 44%. The addition of amicarbazone (79 g ha-1) to mesotrione increased control to 74% by 21 DAT. Topramezone alone or in combination with amicarbazone provided < 10% annual bluegrass control on all rating dates. Fv/Fm and biomass data supported visual observations.

In field experiments, mesotrione provided 78% annual bluegrass control 56 DAT. Amicarbazone alone provided 58, 78 and 96% control at the 79, 160 and 240 g ha-1 rates, respectively, 56 DAT. Mesotrione + amicarbazone provided > 96% control 56 DAT at all rates. These data indicate annual bluegrass control provided by mesotrione can be improved by the addition of amicarbazone.

POTENTIAL ANTAGONISM OF SULFENTRAZONE AND FENOXAPROP TANK-MIXES FOR GOOSEGRASS CONTROL. A.J. Patton*, D.V. Weisenberger, J.T. Brosnan, and G.K. Breeden, Purdue University, W. Lafayette, IN (104)


Several herbicides are known antagonize grassy weed control when tank-mixed with fenoxaprop. The objectives of this research were to evaluate sulfentrazone and fenoxaprop applied alone and in combination with one another for postemergence goosegrass (Eleusine indica) and smooth crabgrass (Digitaria ischaemum) control. Initial experiments were conducted on separate stands of goosegrass and crabgrass at the W.H. Daniel Research and Diagnostic Center in West Lafayette, IN in 2010. Treatments included the factorial combination of fenoxaprop (0.05 and 0.075 kg/ha) and sulfentrazone (0.28 kg/ha). An untreated control was included for comparison. Experimental design was randomized complete block with three replications and plot size measured 2.25 m2. Treatments were applied to 2 to 3 tiller goosegrass and 4 to 5 tiller crabgrass in 814 L/ha water with a CO2-pressurized sprayer at 207 kPa. In 2010 in West Lafayette, goosegrass coverage was lowest from treatments containing fenoxaprop. Goosegrass was not effectively controlled when sulfentrazone was applied at 2-3 tillers. When sulfentrazone was tank-mixed with fenoxaprop, higher goosegrass coverage was present following applications than when fenoxaprop was applied alone suggesting that antagonism was occurring when these products are tank-mixed. No antagonism was observed with these treatments on crabgrass. Experiments were replicated in 2011 at the W.H. Daniel Research and Diagnostic Center (West Lafayette, IN) and the East Tennessee Research and Education Center-Plant Sciences Unit (Knoxville, TN). Treatments included the factorial combination of fenoxaprop (0.05, 0.075, and 0.1 kg/ha), and sulfentrazone (0.28 kg/ha) with an untreated control also included for comparison. Results in 2011 in Indiana mirrored those observed in 2010.  In Tennessee, no antagonism was observed with fenoxaprop and sulfentrazone tank-mixtures applied to goosegrass or smooth crabgrass. Additional research will be conducted in 2012 to determine the reason for the inconsistent response between locations.

COOL-SEASON TURFGRASS RESEEDING INTERVALS FOR METHIOZOLIN. P. McCullough and D... Gomez de Barreda*, Polytechnic University of Valencia, Valencia, Spain (105)


Methiozolin has potential for selective annual bluegrass control in cool-season grasses and practitioners may wish to reseed in treated areas after applications.  The objective of this field experiment was to evaluate reseeding intervals of three cool-season turfgrasses following methiozolin applications at four application timings before seeding.  Methiozolin (2.1 EC) was applied at 0, 0.56, 1.1, or 2.2 kg a.i./ha and compared to bispyribac-sodium (Velocity 17.6WG) at 45 g ai/acre.  Herbicide treatments were applied 0, 2, 4, or 6 weeks before seeding on April 13, 2011.  A broadcast glyphosate application was made 7 days before seeding to kill existing vegetation and facilitate visual assessment of creeping bentgrass, perennial ryegrass, and tall fescue seeded perpendicular to herbicide treatments.

All methiozolin applications on the day of seeding reduced turf cover by approximately 75 to 90% from the untreated for all grasses at 14 days after seeding and were more injurious than bispyribac-sodium by eight weeks after treatments.  Methiozolin at 1.1 and 2.2 kg/ha applied two weeks before seeding reduced cover of all three grasses by approximately 35 to 50% from the untreated after 14 days but 0.56 kg/ha at this timing did not reduce final ground cover. Grasses established in plots treated with 0.56 and 1.1 kg/ha two weeks before seeding had similar cover to the untreated after six weeks.  However, 2.2 kg/ha of methiozolin reduced establishment of all three grasses after eight weeks. Methiozolin at 2.2 kg/ha was the only rate that reduced creeping bentgrass and perennial ryegrass cover from the untreated when applied four weeks before seeding, but did not inhibit tall fescue establishment.  All herbicides applied six weeks before seeding did not reduce establishment of the three grasses on any other evaluation date.  Results suggest reseeding intervals after methiozolin applications vary depending on turf species and application rate.  Due to temporary stunting and potential turf cover reductions, it appears practitioners should wait two, four, and six weeks before seeding in areas treated with methiozolin at 0.56, 1.1, and 2.2 kg/ha, respectively. 

ENLIST CORN TOLERANCE AND WEED CONTROL WITH PRE FOLLOWED BY POST HERBICIDE PROGRAMS. B.D. Olson*, S.C. Ditmarsen, C.A. Gallup, M.W. Melichar, and P.L. Prasifka, Dow AgroSciences LLC, Geneva, NY (106)


The EnlistTM trait in field corn has been extensively evaluated in research trials since 2006.  Enlist corn has demonstrated excellent tolerance to 2,4-D in single and sequential treatments applied preemergence and postemergence at rates up to 4480 g ae/ha per application.  The Enlist trait has been stacked with SmartStax® traits to confer both 2,4-D and glyphosate tolerance.  Enlist Duo™ herbicide is a novel premix containing the active ingredients 2,4-D choline and glyphosate dimethylamine (DMA) under development by Dow AgroSciences for use on Enlist crops.  Dow AgroSciences will be recommending the use of soil residual herbicides as a part of the Enlist Weed Control system to provide early season weed control for crop yield protection and weed resistance management by providing additional modes of action. 

 Field research trials were conducted in 2011 to evaluate a system approach involving GF-2726, the lead formulation of Enlist Duo, in conjunction with SureStart™ herbicide (acetochlor + clopyralid + flumetsulam).  Crop tolerance studies included GF-2726 plus SureStart at 1X and 2X recommended rates applied at spike stage or 10-11 inch corn.  Additionally, sequential applications of SureStart at 1X and 2X rates applied PRE followed by a POST application of GF-2726 at 1X and 2X rates to 10-11 inch corn were evaluated.  Applications of SureStart plus GF-2726 at spike stage resulted in <1% visual injury 14 days after application.  Applications to 10-11” corn of GF-2726 following or tank mixed with SureStart resulted in <10% injury 14 days after application. 

 Weed control studies were conducted utilizing weed management systems consisting of SureStart PRE followed by POST application of GF-2726 to V4-V5 corn, SureStart plus GF-2726 applied early POST to V2 corn, or SureStart plus GF-2726 applied POST to V4-V5 corn.  SureStart was applied at the full recommended rate for the respective soil type.  The rate of GF-2726 was 1640 g ae/ha. Weed control ratings were taken at 0, 14 and 28 days after the V4-V5 application.  PRE followed by POST, early POST only, or POST only treatments provided >90% control of ABUTH, AMARE, AMATA, AMBEL, AMBTR, CHEAL, IPOSS, SIDSP, and XANST species.


These studies demonstrate the utility of residual herbicides followed by post applications of 2,4-D choline + glyphosate DMA as part of the Enlist Weed Control system in Enlist corn.  Residual herbicides provide an effective means to prevent yield loss due to early season weed competition and bring additional modes of action to the weed control system for weed resistance management best practices.

 Enlist, Enlist Duo, and SureStart are trademarks of Dow AgroSciences LLC. ®SmartStax is a registered trademark of Dow AgroSciences LLC.  Components of the Enlist Weed Control System are pending regulatory approvals. The information provided here is not an offer for sale. ©2011 Dow AgroSciences LLC.



A rotation experiment was established near Aurora, NY in 2010 to determine the value of reduced rates of residual herbicides in preventing dandelion (Taraxacum officinale Weber in Wiggers) encroachment into zone-tillage corn (Zea mays L.) and soybeans (Glycine max Merrill).  The field was fall plowed in 2009 to eliminate established dandelions.  Four-year rotations established as main plots (12 rows by 300 ft) with five replications were: 1) continuous corn with residual herbicides, 2) corn, soybeans, corn, soybeans with residual herbicides in both crops, 3) soybeans, corn, soybeans, corn with residual herbicides in both crops, 4) corn, soybeans, corn, soybeans with residual herbicides in corn only, and 5) soybeans, corn, soybeans, corn with residual herbicides in corn only.  Sub-plots (12 rows by 75 ft) within crops received no residual herbicides, one-half, two-thirds, or full labeled rates of residual herbicides. Corn sub-plots were treated early postemergence (EPOST) with 0.77 lb ae/A of glyphosate alone or tank-mixed with 1.23, 1.64, or 2.46 lb ai/A of a premix of S-metolachlor, atrazine, and mesotrione (Lumax).  Soybean main plots were split into six row strips so two residual programs could be compared.  In one strip, sub-plots received no residual or a premix of metribuzin and chlorimuron-ethyl (Canopy) at 0.84, 1.13, or 1.69 oz ai/A preemergence (PRE) followed by 0.77 lb/A of glyphosate mid-postemergence (MPOST).  In the other strip, sub-plots received no residual or a premix of chlorimuron-ethyl, flumiclorac, and thifensulfuron-methyl (Enlite) at 0.67, 0.89, or 1.34 oz ai/A PRE followed by 0.77 lb/A of glyphosate alone or tank-mixed with a premix of chlorimuron-ethyl and thifensulfuron-methyl (Synchrony XP) at 0.05, 0.07, or 0.11 oz ai/A MPOST.  Glyphosate resistant corn ‘DKC 4272’ and soybeans ‘AG 2130’ were planted May 17 and 25, 2010 respectively. EPOST corn herbicides were applied June 15 to 7 inch corn.  PRE soybean herbicides were applied May 27 and MPOST soybean herbicides were applied June 25 to 6 inch soybeans.  Preliminary dandelion counts were made in a 7.5 by 75 ft area in the center of each sub-plot May 2, 2011.  Counts for corn sub-plot treatments were averaged across rotations since all were treated the same in 2010.  Dandelion counts for corn averaged 182, 3, 2, and 1/1,000 sq ft for sub-plots receiving none, one-half, two-thirds, and full rates of the residual premix respectively.  There were no differences in dandelion counts between the two residual soybean programs and counts averaged 80, 4, 1, and 2/1,000 sq ft for sub-plots receiving none, one-half, two-thirds, and full rates of these residual programs respectively.  There were more dandelions in May 2011 following EPOST glyphosate alone in corn (182/1,000 sq ft) than following MPOST glyphosate alone in soybeans (80/1,000 sq ft).  This difference may be due to the 10 day difference between glyphosate applications in corn and soybeans or to differences in canopies and shading between the two crops. 

ZEMAX: A NEW MESOTRIONE PLUS S-METOLACHLOR FORMULATION IN CORN. E. Hitchner*, R. Lins, M. Urwiler, and G.D. Vail, Syngenta, 08098, NJ (108)


ZemaxTM is a new corn herbicide for pre-emergence and postemergence residual control of grasses and broadleaf weeds.  Zemax can be applied pre-plant, pre-emergence and post-emergence.  The Zemax formulation is based on the same capsule-suspension formulation technology as Halex GT.  The product is formulated for optimized handling, compatibility with sulfur-containing nitrogen fertilizers and other critical tank mix partners, and designed to minimize the effects of overwintering.  ZemaxTM is the latest product in the Callisto Plant Technology® family of herbicides.  

PERFORMANCE OF F9310 AND F9316&NBSP;IN THE NORTHEAST PRE & POST CORN TRIALS IN 2010 AND 2011.&NBSP;. J.P. Reed*, J.S. Wilson, G.G. Stratman, B.A. Neuberger, and T.W. Mize, FMC, North Little Rock, AR (109)


F9310 and F9316 are two new herbicides under development by FMC for preplant, preemergence and postemergence grass and broadleaf weed control in corn.  F9310 is a combination of pyroxasulfone plus fluthiacet-methyl.  F9316 combines pyroxasulfone, fluthiacet-methyl and atrazine. Field research trials have been conducted in the US in 2010 and 2011 to evaluate crop safety and weed control provided by these two herbicides as well as comparisons to other standard PRE and Post herbicides for corn.  Trials were conducted primarily at university research locations as well as independent contract sites across the Midwestern and Eastern Corn Belt, Middle Atlantic States and Southern corn production areas.  Applications included early preplant, preemergence and early postemergence timings across various soil types and geographic distribution of corn growing areas.  Rates of F9310 included 113 to 151, 132 to 169, and 151 to 188 g ai/ha on coarse, medium and fine soils, respectively.  Rates of F9316 ranged from 0.95 kg ai/ha to 1.58 kg/ha across all three soil classes.  Visual evaluations crop response as well as both grass and broadleaf weed control were evaluated.   Crop response was low across most trials.  F9310 and F9316 demonstrated excellent crop safety across all trials with a maximum of 5% crop response with F9316 recorded in 1 trial out of 39 sites. F9310 did not show any crop response from preemergence applications. Crop response from postemergence applications was low, averaging 5% with both F9310 and F9316 as leaf speckling or spotting from the fluthiacet-methyl as reported at 7- 30 DAT.  Results at 3-6 weeks after treatment indicated excellent control of foxtail and panicum species and similar to other preemergence grass herbicides.   Both F9310 and F9316 applied preemergence provided excellent control of several key broadleaf weed species including tall waterhemp, Palmer amaranth, common lambsquarters, and velvetleaf.  F9316 provided greater overall control on common and giant ragweed, morningglories, velvetleaf, and greater consistency of control on waterhemp and common lambsquarters versus F9310.  Both F9310 and F9316 provided excellent control of grass and broadleaf weeds when tank-mixed with glyphosate and applied postemergence.  Control of foxtails, waterhemp, Palmer amaranth, lambsquarters, and morningglories, and velvetleaf was 90% or greater at 15-30 DAT.  Excellent residual of both F9310 and F9316 when applied postemergence was observed.  Lower levels of control were observed with treatments of glyphosate alone during this same evaluation period due to new weed flushes.   F9316 provided greater control of giant ragweed, waterhemp than F9310 during the same evaluation period.   Both F9310 and F9316 have been shown to be effective grass and broadleaf tools for flexible weed management in corn.  Further research to develop effective weed management programs incorporating these herbicides is needed. 



Adoption of no-tillage agriculture holds a number of benefits including soil and water conservation, potential improvements in soil quality, reduced energy costs, and implications for carbon sequestration.  At the same time, no-tillage systems rely chiefly on herbicides for weed management increasing some environmental risks and the evolution of herbicide resistant weeds.  Diversifying crop rotations can help alleviate many pest problems including weeds and is even more important in continuous no-till systems.  In no-till, herbicides are often required for control of emerged vegetation at the time of crop establishment.  Glyphosate is the dominant nonselective burndown herbicide choice in many no-till systems and a number of selective herbicides can be included depending on the crop and application timing.  However, for a number of reasons, glyphosate is often applied without tank-mix partners to control emerged vegetation.  Using a single mode of action is a particular concern for herbicide resistance, so adding other effective herbicide modes of action to the program is warranted.   The addition of 2,4-D can help broaden the weed control spectrum and reduce the potential for herbicide resistant broadleaf weeds.   Although this combination is frequently used in no-till corn and soybean, labeling restrictions and concerns about crop injury have limited its utility in other crops.

To test the safety of 2,4-D in no-till establishment of some minor crops, an experiment was conducted in 2011 at the Russell Larson Research and Education Center near State College, Pennsylvania.   The ester formulation (LVE) of 2,4-D was applied at 0.25, 0.5, 1.0, and 2.0 lb ae/acre to wheat stubble in late summer.  The amine formulation of 2,4-D and the diglycolamine salt of dicamba were also included at 0.5 lb ae/acre each.  Glyphosate was tank-mixed with all herbicides at 0.75 lb ae/acre to aid in the control of emerged vegetation.  Alfalfa (Medicago sativa L.), red clover (Trifolium repens L), hairy vetch (Vicia villosa Roth), crimson clover (Trifolium  incarnatum L.), canola (Brassica napus L.), and daikon radish (Raphanus sativus L.) were seeded the same day of herbicide application (0 day), and 7, 14, and 21 days after herbicide application.  About one month after seeding, crops were evaluated visually for injury and in selected treatments above-ground biomass was harvested about 8 weeks after seeding.

In the 0 day seeding, 2,4-D LVE injury increased with rate ranging from 32 to 85% for alfalfa, 27 to 80% for red clover, 20 to 72% for crimson clover, 27 to 70% for hairy vetch, 21 to 81% for canola, and 16 to 76% for daikon radish.   By 7 days after application, alfalfa injury did not exceed 19%, red clover 17%, crimson clover 11%, hairy vetch 14%, canola 29%, and daikon radish 12%.  By 14 days after application, crop injury was mostly undetected even at the 2.0 lb rate of 2,4-D.  Crop injury from the amine formulation was similar to the ester.  Dicamba crop injury was observed in all species at up to 7 days after application, but had also mostly dissipated by 14 days.  Rainfall during the experiment was frequent and exceeded normal (almost 13 inches for August and September) and may have helped increase the rate of dissipation.  The results from this trial suggest that 2,4-D tank mixtures may have greater utility for burndown application in minor use crops, but additional research is necessary before reliable recommendations can be made.



Troublesome weed species are those which are most difficult for farmers to control. Life cycle, herbicide resistance, high compatibility with crop management systems, and ideal climatic conditions are a few factors that can contribute to a weed’s designation as “troublesome”. In this survey, we identified which weeds are most troublesome for grain corn, silage corn, soybean, and winter wheat growers in fourteen Northeastern U.S. states and investigated whether crop management practices influenced weed species composition. We sought to determine if certain weeds are troublesome within their total range or a portion of their range by comparing their occurrence distributions within temperature and rainfall-defined sub-regions. Current weed distribution maps, when paired with these climatic data, can be used to predict range expansions of “troublesome” weed species over time. We also examined whether herbicide resistance contributed to the designation of a weed as being “troublesome”. A survey was developed and electronically mailed to 462 cooperative extension employees, certified crop advisors, researchers, and industry professionals and the NEWSS member list-serve. As of late October 2011, a total of 70 participants contributed 120 survey submissions providing more than 1142 listings of “troublesome” weeds from 37 of the 62 sub-regions. Preliminary data indicated that climate region and herbicide resistance both influenced the distribution of some “troublesome” species. For example, the species considered most “troublesome” in New Hampshire (NH) corn cropping systems were yellow nutsedge (Cyperus esculentus L.), common lambsquarters (Chenopodium album L.), quackgrass (Elymus repens (L.) Gould), and velvetleaf (Abutilion theophrasti Medik.). Moving south, the most “troublesome” weeds in Pennsylvania (PA) corn crops were burcucumber (Sicyos angulatus L.), common cocklebur (Xanthium strumarium L.), common lambsquarters, and common ragweed (Ambrosia artemisiifolia L.) while in Virginia (VA) Palmer amaranth (Amaranthus palmeri S. Wats.), morningglory species (Ipomoea spp.), field bindweed (Convolvulus arvensis L.), and fall panicum (Panicum dichotomiflorum Michx.) were considered most troublesome in corn systems. Species tended to be most troublesome in only a subset of their known range. A morningglory species (Ipomoea spp.) was reported as troublesome once in New England and ranked 29th out of the 39 reported species. Rankings of 13 of 33 in PA, 2 of 28 in VA, and 1 of 28 in the Mid-Atlantic states suggest that morningglories are most problematic in more southern regions of the Northeast. Herbicide resistance in horseweed (Conyza canadensis (L.) Cronq.) contributed to its being considered “troublesome” in soybean crops. Delaware (DE) and PA ranked horseweed as the most “troublesome” soybean weed, with resistance reported in all cases in DE and 11 of 13 cases in PA. Horseweed was not a top troublesome species in VA, Vermont, or New Jersey, where 50% or less of responses indicated herbicide resistance. On-going work will focus on developing “troublesome” distribution maps for various species, examining the effect of climate, tillage, herbicide resistance, and cropping system on “troublesome” weed ranges.  Once data have been compiled, results will be made available to all participants.

HERBICIDE RESISTANCE EDUCATION - A CRITICAL STEP IN PROACTIVE MANAGEMENT. W.J. Everman*, L. Glasgow, L. Ingegneri, J. Schroeder, D. Shaw, J. Soteres, J. Stachler, and F. Tardif, North Carolina State University, Raleigh, NC (112)


Herbicide resistance education and training have been identified as critical paths toward advancing the adoption of proactive best management practices to delay and mitigate the evolution of herbicide-resistant weeds. In September 2011, the Weed Science Society of America (WSSA) introduced a training program designed to educate certified crop advisors, agronomists, pesticide retailers and applicators, growers, students, and other interested parties on the topic of herbicide resistance in weeds. A peer reviewed, five-lesson curriculum is currently available at the Society’s web page via web-based training and PowerPoint slides. Topics include: (1) An introduction to herbicide resistance in weeds (2) How do herbicides work? (3) What is herbicide resistance? (4) How do I scout for and identify herbicide resistance in weeds? and (5) How do I manage resistance? The lessons are unique among herbicide resistance training materials in that, for the first time, the WSSA presents a unified message on the causes of herbicide resistance and offers several strategies for identifying and mitigating herbicide resistance in weeds. The lessons contain the most up-to-date definitions for use in the field, including those for low- and high-level resistance, a video on how to scout for herbicide-resistant weeds, and an emphasis on proactive management. The lessons utilize animations to showcase these important points. A Spanish-language version has been also produced.  Greater than 380 downloads were documented within the first two months that the lessons were available.

STEWARDSHIP OF DICAMBA IN DICAMBA TOLERANT CROPPING SYSTEMS. W.E. Thomas*, S.J. Bowe, L.L. Bozeman, M. Staal, T. Cannan, and S.W. Murdock, BASF Corporation, Research Triangle Park, NC (113)


New weed control options are needed to manage a growing weed resistance problem that is limiting control tactics and in some areas cropping options.  Glyphosate is an important herbicide in many cropping systems, but problematic weeds like Palmer amaranth (Amaranthus palmeri), waterhemp (Amaranthus tuberculatus), giant ragweed (Ambrosia trifida), and horseweed (Conyza canadensis) have been confirmed resistant to it in at least 24 states.  And many of these populations are also resistant to more than one herbicide mode of action.  Given the limited herbicide options in many cropping systems, these weeds present significant management problems for producers.  The dicamba tolerant cropping system will offer growers a new weed management option in cotton (Gossypium hirsutum) and soybean (Glycine max).  Dicamba complements the weed control spectrum of glyphosate and controls many broadleaf weeds that have been reported to be resistant to glyphosate.  However, proper implementation of the dicamba tolerant cropping system is required to ensure its long term sustainability.  As part of an integrated strategy, one should consider several stewardship tactics to address weed resistance management and on-target deposition.  Weed management programs should consider an integrated system using multiple herbicide modes of action, effective rates and timings, and site monitoring as well as mechanical weed control when necessary.  Maximizing on-target deposition can be addressed with formulation and application techniques including nozzle selection, boom height, and spray pressure.  Environmental conditions such as wind and inversions also have significant influence on the level of on-target deposition and need to be considered before application.  The goal of such a stewardship program is to allow growers to maintain flexibility and control of their farming operation.  A training and education program can assist growers in achieving this goal.  An improved formulation, optimized application techniques, and integration of other effective weed control tactics like alternate modes of action, tillage, and crop rotation will ultimately provide the most sustainable production system. 

EFFICACY OF F9310 AND SULFENTRAZONE PREMIXES &NBSP;IN THE NORTHEAST SOYBEAN TRIALS IN 2011.&NBSP;. J.P. Reed*, J.S. Wilson, G.G. Stratman, B.A. Neuberger, and T.W. Mize, FMC, North Little Rock, AR (114)


F9310 (Anthem) is a new herbicides under development by FMC Corporation for preplant, preemergence and postemergence grass and broadleaf weed control in soybeans.  F9310 is a combination of pyroxasulfone plus fluthiacet-methyl.  Field research trials have been conducted at university sites in 2011 to evaluate crop safety and weed control provided by F9310, along with comparisons to other standard PRE and Post herbicides for soybeans.  Trials were conducted primarily at university research locations in Midwestern and Eastern Corn Belt, Middle Atlantic States and Southern corn production areas..  Applications included preemergence and early postemergence timings across various soil types and geographic locations of major soybean growing areas.  Rates of F9310 included 146 g ai/ha applied preemergence, 110 g ai/ha applied postemergence, and 91 g ai/ha applied postemergence in a treatment combination or an overlap system with a sulfentrazone herbicide applied preemergence. Visual evaluations included crop response at 14 and 28 days after crop emergence for preemergence applications, and 7 and 21 days after postemergence applications.   Preemergence applications of F9310 demonstrated excellent crop safety across all trials and was comparable to other standard preemerge herbicides. Crop response from postemergence applications of F9310 was low and was reported as minor leaf speckling or spotting associated from the fluthiacet-methyl.  Weed control ratings for preemergence application were taken just prior to a glyphosate postemergence treatment.  Results at 3-4 weeks after treatment indicated excellent control of foxtail species with results similar or slightly better than standard preemergence grass herbicides.   F9310 applied preemergence also provided excellent control of several key broadleaf weed species including tall waterhemp, and good control of common lambsquarters, common ragweed, and velvetleaf.  F9310 provided excellent control of grass and broadleaf weeds when tank-mixed with glyphosate and applied postemergence.  F9310 (Anthem) has shown to be an effective grass and broadleaf tool for flexible weed management in soybeans. 

UPDATE ON HPPD-RESISTANT WATERHEMP AND CONTROL OPTIONS IN CORN AND SOYBEANS. K.D. Burnell*, V.K. Shivrain, A.S. Franssen, and G.D. Vail, Syngenta Crop Protection, Penfield, NY (115)


Field studies were conducted on waterhemp (A. tuberculatus, syn. rudis) which is resistant to post-emergence HPPD inhibiting herbicides. Pre-emergence application of mesotrione alone and in combination with s-metolachlor and atrazine provided effective control. Also, s-metolachlor in combination with metribuzin and fomesafen applied pre-emergence controlled the waterhemp. Post- emergence herbicides including glyphosate, glufosinate, fomesafen and synthetic auxins provided effective control.



M.S. Technologies and Bayer CropScience are developing a new soybean event that is tolerant to both glyphosate and p-hydroxyphenyl pyruvate dioxygenase (HPPD) inhibitor herbicides.  Tolerance to glyphosate is similar to commercially available soybean lines.  There is differential tolerance to HPPD inhibiting herbicides in this new event.  This event is tolerant to preemergence applications of isoxaflutole and mesotrione.  There are varying levels of tolerance to postemergence applied HPPD inhibitors.  This event exhibits the best postemergence tolerance to isoxaflutole.  There is reduced tolerance to mesotrione and tembotrione in this soybean event. 



Anthem is a new proprietary herbicide premix than contains pyroxasulfone and fluthiacet-methyl that provides growers a convenient and flexible product for pre-emergence and early post emergence grass and broadleaf weed control. Anthem is formulated as a 2.15 pound per gallon suspoemulsion liquid. Anthem will be labeled for both corn and soybean uses. Anthem ATZ is a new three way herbicide premix than contains pyroxasulfone, atrazine and fluthiacet-methyl that provide growers a convenient and flexible product for pre-emergence and early post emergence grass and broadleaf weed control. Anthem ATZ is formulated as a 4.5 pound per gallon suspoemulsion liquid. Anthem ATZ will be labeled for corn uses only. Both Anthem and Anthem ATZ offers growers several modes of action for control of weeds, including weeds resistant to glyphosate and many difficult to control species. Both products provide excellent crop safety when used at the recommended pre-emergence rates for the particular soil type or in post applications. Anthem uses rates will vary from 6-13 fluid ounces per acre and Anthem ATZ uses rates will vary from 1.5 to 4 pints per acre. Research trials conducted by FMC and University researchers has shown excellent grass and broadleaf weed control with both Anthem and Anthem ATZ.



The Northeast Sustainable Agriculture Research and Education (NESARE) program has used an outcome funding framework since 2000. Other USDA grant programs such as some of the National Institute of Food and Agriculture (NIFA) programs have recently switched to an outcome funding framework. One of the main reasons NESARE switched to outcome funding was to obtain more adoption of research findings by farmers, which is NESARE’s primary mandate from Congress. Outcome funding enables more adoption of new information by farmers because it requires that researchers have measurable goals for changes in the behavior or condition of farmers that are engaged with their research. Accomplishing these goals requires all research projects to have an educational program, deliberate and intensive engagement with farmers, and a plan for verifying changes resulting from the engagement. Most non-outcome funded research grant programs focus on obtaining research results, with only a small emphasis on the adoption of these results by the clientele being served. The change to outcome funding by NESARE made it difficult for some researchers to compete for NESARE grant funds. Researchers who were not accustomed to thinking in terms of how their research could be adopted by farmers were at a disadvantage. Researchers who were already working with farmers to plan, implement and evaluate their research, however, became highly successful in NESARE’s program after 2000. Writing competitive proposals in an outcome funded grant program like NESARE’s requires close cooperation with farmers, knowledge about how adults learn, and an effective verification plan to document the amount of adoption at the end of a grant, rather than a description of the type and quantity of activities that will occur. This presentation will provide a mini-workshop about outcome funding as practiced by NESARE. Key concepts used in outcome funding will be explained and characteristics of strong proposals will be discussed.