Persistence of fungicides applied to control snow mold of turfgrass as influenced by snow cover and antitranspirants.

Turfgrass managers rely on fungicides to suppress snow mold diseases in areas with persistent snow cover, which are commonly applied once or twice in late fall prior to snow cover. Fungicide applications targeting snow mold are expected to control snow mold diseases for the duration of winter; however, climate change is increasing the frequency of winter rainfall and snowmelts and may alter the duration of snow mold control. A 3-year study was conducted in Madison, WI to assess the impact of snow cover and antitranspirants on the persistence of the commonly used fungicides chlorothalonil and propiconazole. Snow cover, fungicide treatment, and the use of antitranspirants had minimal impacts on fungicide persistence and disease control. The most important factors influencing persistence of the fungicides were snowmelt and winter rainfall events, yet antitranspirants demonstrated modest evidence of extending chlorothalonil persistence in certain years. These results demonstrate that increasing snowmelt and winter rainfall events associated with climate change will increase dissipation of fungicides used for snow mold suppression which will likely impact disease control.