FALL APPLICATIONS OF PRODIAMINE + SULFENTRAZONE FOR PREEMERGENCE CONTROL OF ANNUAL BLUEGRASS AND CRABGRASS.   C. Johnston and P. McCullough; Department of Crop and Soil Sciences, University of Georgia, Griffin, GA 30223. 

ABSTRACT 

Preemergence herbicides are applied in fall for annual bluegrass (Poa annua) control and residual effects may control summer annual weeds.  The objective of this research was to evaluate efficacy of fall applications of Echelon (prodiamine + sulfentrazone) at 1.25 kg ai/ha applied as a granular (G), suspension concentrate, or water dispensable granule compared to prodiamine at 0.56 or 0.84 kg ai/ha, F9001 (0.3G) at 1 kg ai/ha, and indaziflam at 53 g ai/ha.  Applications were made on October 3, 2011 to a ‘Tifway’ bermudagrass (Cynodon dactylon x C. transvaalensis) fairway.  All treatments provided complete control of annual bluegrass at 203 days after applications (DAA).  Echelon, F9001, and prodiamine treatments provided poor control of parsley-pert (Aphanes arvensis) but indaziflam provided complete control at 203 DAA.  At 332 DAA, the granular Echelon formulation and F9001 provided excellent control (≥90%) of smooth crabgrass but control was (<70%) from other treatments.  Results suggest all Echelon formulations provided comparable control of annual bluegrass to prodiamine and indaziflam in fall while the granular formulation and F9001 had enough residual to control smooth crabgrass at the rates tested.