Effect of post application irrigation timing on fungicide efficacy of dollar spot on golf putting greens

Abstract

Evaluation of the impact of post application (PA) irrigation or rainfall on performance of modern fungicide chemistries is lacking. Spring applications targeting soilborne diseases on putting greens require PA irrigation, which may impact control of foliar diseases such as dollar spot. In this study, four different fungicides with varying phytomobility and modes of action (fluazinam, mefentrifluconazole, pydiflumetofen, and prothioconazole) were applied to a golf course putting green to assess the effect of PA water application on foliar disease control. After fungicide application, 5.1 mm of water was applied to each treatment at four different timings (no water, immediate, 1 h, and 12 h) with an irrigation simulator. The study was replicated twice, once at the 12.8°C soil temperature threshold (May 1) and once when the Smith–Kerns Dollar Spot Prediction Model exceeded 25% probability (May 19). The impact of PA irrigation timing on fungicide efficacy for dollar spot control timing varied among the different fungicides and run timing. Effective fungicide chemistries applied earlier in the spring and applied during predicted favorable conditions for disease development both provided dollar spot control to June 25 and 27, respectively.