Evaluating BEETcast™, a disease forecasting model, for timing fungicide sprays with CR+™ varieties.

Varieties are available that have a strong tolerance to Cercospora Leafspot (CR+™). In the Michigan Sugar Company growing region, growers have sprayed fungicides for Cercospora Leafspot using calendar dates and a disease forecasting model BEETcast™.  With the stronger variety tolerance to Cercospora Leafspot studies were conducted to determine the optimal spray interval by variety. Multiple varieties with a range of Cercospora Leafspot tolerance from high to low were tested by spraying fungicides at intervals of every 15 days, 35 disease severity values (DSV’s) and 55 DSV’s. Varieties with strong Cercospora Leafspot tolerance performed well when sprayed every 55 DSV’s. Varieties with weaker Cercospora Leafspot tolerance needed to be sprayed every 15 days or at 35 DSV’s.