Additional uses of the Smith–Kerns dollar spot model for improved dollar spot suppression

Abstract

The Smith–Kerns Dollar Spot Model has been used to time preventative fungicide applications to optimize control, but additional uses of the model may expand its impact and further reduce unnecessary fungicide. This project investigates two additional uses of the model, (1) to assess whether early-season fungicide applications allow for increased model thresholds to be used the rest of the season and (2) to determine whether the model can be used to schedule when reductions in fungicide reapplication intervals are most effective. Both studies were conducted in Madison, WI, in 2022 and 2023. In the early-season study, inclusion of an early-season fungicide did not provide significant evidence for increased model thresholds to be used the remainder of the season. In the reapplication interval study, a model threshold of 60% indicated that dollar spot pressure was high, suggesting that reapplication intervals should be shortened. Collectively, these results provide additional uses of the Smith–Kerns Dollar Spot Model and increase the ability for golf course superintendents to implement data-driven strategies in their dollar spot management programs.