Implementation of BeetCast, a predictive model for managing cercospora leafspot, in Michigan. BeetCast is a predictive model designed to improve fungicide application timing for management of cercospota leafspot. The objective of this study was to evaluate the accuracy of BeetCast in Michigan. Studies were conducted at six locations; Beckenridge, Saginaw, Fairgrove, Pigeon, Sandusky and Ruth, MI. Treatments included applying fungicides based on BeetCast and applying fungicides based on visual

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... sease symptoms. BeetCast combines temperature and leaf wetness to create a disease severity value (DSV). The DSV can be used to predict cercospora leafspot disease development. Fungicides can then be applying based on the number of disease severity values (DSVs) that have accumulated. Traditionally fungicides were applied based on ftrst symptoms of disease (l st spot) and then reapplied every 14 to 21 days after 1sl spot based on the fungicide label. Fungicides were ftrst applied when 55 DSVs accumulated, 70 DSVs accumulated and when the 1st spots appeared. Follow up applications were made when 35 DSVs accumulated, 55 DSVs accumulated, 70 DSVs accumulated and when 18 days had passed. Following BeetCast by applying fungicides when 55 DSVs accumulated required fewer fungicide applications compared applying fungicides based on visual disease symptoms to achieve the same level of cercospora leafspot control. In 2 of 6 locations, sugarbeet yield was improved by applying fungicides starting when 55 DSVs accumulated, and then reapplying fungicides when 35 or 55 DSVs accumulated, compared to applying fungicides every 70 DSVs or based on visual disease symptoms.