Formulation, application timing, and postapplication irrigation timing affect dislodgeable azoxystrobin from turfgrass

Abstract

AbstractAzoxystrobin is a broad‐spectrum strobilurin fungicide used widely in turfgrass systems, including lawns. Previous research has shown that various management practices influence pesticide dislodgement from turfgrass; however, limited research has been performed to determine their effect on azoxystrobin dislodge. A field experiment was conducted in Raleigh, NC, to quantify dislodgeable azoxystrobin (0.61 kg ai ha−1) foliar residue from tall fescue [Lolium arundinaceum (Schreb.) S.J. Darbyshire] across formulations (sprayable or granular), application timings (AM [0700 h Eastern Standard Time] or PM [1400 h Eastern Standard Time]), and postapplication irrigation timings (4 or 48 h after treatment [HAT]). Sample collection occurred 1, 2, 3, 4, 8, or 16 d after treatment (DAT). Evaluated management practices affected dislodgeable azoxystrobin, most notably from 1 to 4 DAT. Sprayable azoxystrobin applied in the PM resulted in greater azoxystrobin dislodged (1.0–8.0% of applied) compared with AM (0.3–5.5%), which were both greater than granular azoxystrobin applied in the AM or PM (<0.1–2.8%) from 1 to 4 DAT. Within sprayable azoxystrobin, five times greater azoxystrobin was dislodged by delaying postapplication irrigation until 48 HAT (1.2–11.8% of applied) compared with irrigation 4 HAT (0.2–1.2%) from 1 to 4 DAT. Information from this study improves our understanding of factors affecting pesticide dislodge and can be incorporated into turfgrass management strategies to minimize potential human pesticide exposure.