Influence of post‐application irrigation and mowing timing on fungicide fate on a United States Golf Association golf course putting green

Abstract

Fungicides are routinely applied to golf course putting greens throughout the growing season. Gaining a better understanding of fungicide fate can improve fungicide use and stewardship. Therefore, optimizing fungicide applications with postapplication management practices may enhance fungicide movement and limit potential off-target effects. Two field studies were initiated on a golf course putting green to evaluate the influence of post-fungicide application irrigation and mowing timing on fungicide movement into the soil profile and removal in turfgrass clippings. Plots were treated with a single application of either pyraclostrobin, triadimefon, or penthiopyrad and received 0.64 cm post-application irrigation immediately or 6 h after application or received no post-application irrigation. Clippings were collected 0, 1, and 3 d after treatment (DAT). Cores were harvested 0, 1, 3, 5, 7, and 14 DAT and dissected into the remaining aboveground vegetation (RAV; verdure/thatch; 0-to-2.5-, 2.5-to-5.1-, and 5.1-to-7.6-cm soil subsections). A small amount of fungicide (<3.6%) was removed with clippings regardless of mowing and irrigation treatment. Post-application irrigation treatment influenced fungicide movement; however, >50% of fungicide remained restricted to the RAV for the first 3 DAT. Less fungicide remained restricted to the RAV, and more fungicide was detected in deeper soil depths when plots were irrigated immediately after application. Fungicide was only detected at the 5.1-to-7.6-cm depth when plots were irrigated immediately.Applying post-application irrigation immediately may result in more fungicide moving down to soilborne targets. Irrigating 6 h after application facilitated moderate fungicide movement compared with irrigating immediately but was better than no post-application irrigation.