Persistence in and Release of 2,4‐D and Azoxystrobin from Turfgrass Clippings

Research has shown that pesticide residue in clippings from previously treated turfgrass may become bioavailable as grass decomposes, adversely affecting off‐target organisms. We conducted a field study to quantify 2,4‐D (2,4‐dichlorophenoxyacetic acid) and azoxystrobin (methyl(E)‐2‐{2[6‐(2‐cyanophenoxy)pyrmidin‐4‐yloxy]phenyl}‐3‐methoxyacrylate) residues in turfgrass clippings collected from hybrid bermudagrass [ Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt–Davy], tall fescue [ Lolium arundinaceum (Schreb.) S.J. Darbyshire], and zoysiagrass ( Zoysia japonica Steud.). A subsequent greenhouse experiment was conducted to measure pesticide release from clippings into water. 2,4‐D (1.6 kg a.i. ha −1 ) and azoxystrobin (0.6 kg a.i. ha −1 ) were applied to field plots at 32, 16, 8, 4, 2, 1, or 0 d before collection of the clippings. Clippings were collected from each experimental unit to quantify pesticide release from clippings into water. Both 2,4‐D and azoxystrobin were detected when turfgrass was treated over the 32‐d experimental period, suggesting that clipping management should be implemented for an extended period of time after application. Pesticide residue was detected in all water samples collected, confirming 2,4‐D and azoxystrobin release from turfgrass clippings; however, pesticide release varied between compounds. Two days after clippings were incorporated in water, 39 and 10% of 2,4‐D and azoxystrobin were released from clippings, respectively. Our research supports the currently recommended practice of returning clippings to the turfgrass stand when mowing because removal of 2,4‐D and azoxystrobin in clippings may reduce pest control and cause adverse off‐target impacts. Core Ideas 2,4‐D and azoxystrobin residues were detected in clippings 32 d after treatment. 2,4‐D and azoxystrobin were released from turfgrass clippings into water. Pesticide release from turfgrass clippings into water varied between compounds.