EFFICACY OF AMINOCYCLOPYRACHLOR FOR CONTROLLING CRABGRASS, SWINECRESS, and VIRGINIA BUTTONWEED IN TALL FESCUE.  T. Reed and P. McCullough; Department of Crop and Soil Sciences, University of Georgia, Griffin, GA 30223. 

 ABSTRACT

Field experiments were conducted to evaluate efficacy of aminocyclopyrachlor and other herbicides for controlling swinecress (Coronopus didymus (L.) Sm.), smooth crabgrass (Digitaria ischaemum Shreb.), and Virginia buttonweed (Diodia virginiana L.) in tall fescue (Festuca arundinacea Schreb.). Aminocyclopyrachlor at 0.05 and 0.10 kg a.i./ha provided <35% control from February applications but both rates gave >90% control with April applications.  Fluroxypyr at 0.26 and 0.52 kg a.i./ha provided poor (<70%) control from February applications but control increased to 71% and >90% from April treatments, respectively. Triclopyr at 0.56 and 1.12 kg a.i./ha provided >90% swinecress control at both application timings and was comparable to 2,4-D + dicamba + MCPP.  In other experiments, single applications of aminocyclopyrachlor at 0.05 and 0.08 kg ai ha^-1 provided poor (<70%) and fair (70 to 79%) control of Virginia buttonweed, respectively, but sequential applications improved control 83 to 99%.  Single and sequential applications of aminocyclopyrachlor at 0.11 kg ai ha^-1 provided good (80 to 89%) and excellent (>90%) control of Virginia buttonweed, respectively.  Aminocyclopyrachlor at 0.11 kg ha^-1 provided fair control of smooth crabgrass at the multi-leaf stage but control was poor when applied at the multi-tiller stage.  Aminocyclopyrachlor at 0.05 and 0.08 kg ha^-1 provided poor control of crabgrass at both timings and were less effective than fenoxaprop at 0.10 kg ai ha^-1.