Aminocyclopyrachlor Efficacy for Controlling Virginia Buttonweed (Diodia virginiana) and Smooth Crabgrass (Digitaria ischaemum) in Tall Fescue

Abstract

Virginia buttonweed and smooth crabgrass are problematic weeds in tall fescue and may warrant control with herbicides at similar timings. The objectives of these field experiments were to evaluate (1) aminocyclopyrachlor rate and application regimens for controlling Virginia buttonweed and (2) the influence of growth stage on aminocyclopyrachlor efficacy for controlling smooth crabgrass. 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 to 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 multileaf growth stage prior to tillering but control was poor when applied at the multitiller 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.