Cercospora leaf spot, caused by Cercospora beticola Sacc., is the most detrimental disease of sugar beet (Beta vulgaris L.) in the Great Lakes Region. Field trials determined efficacy of BEETcast™ 50/35, BEETcast™ 55/50, and calendar spray schedules using 115 or 235 L ha 1 carrier volume with disease severity value (DSV) accumulation beginning at 1 May or crop emergence. Disease progress was minimized by spray schedules with conservative application intervals compared to longer application intervals. Area under the disease progress curve was reduced by a carrier volume of 235 L ha 1 compared to 115 L ha 1 at one of five sites, and DSV start date at emergence compared to 1 May at one of two sites. Aerial C. beticola conidia concentration was assessed in 6 h intervals and peaked in September with daily mean maxima from noon to 6 pm. Daily mean air temperature was related to daily mean conidia concentration when all data were considered and when concentration exceeded 30 spores m 3.