Evaluation of Fungicide Spray Programs with Differential Application Timing to Manage Cercospora Leaf Spot in a Highly Tolerant Sugar Beet Variety in Northwest Minnesota, 2025

Cercospora leaf spot (CLS), caused by Cercospora beticola, is among the most devastating foliar diseases of sugar beet. Small, circular tan to brown leaf spots often coalesce into large necrotic lesions under severe infections, leading to defoliation, reduced root yield and sugar recovery. In this study, we evaluated the efficacy of fungicide spray programs with emphasis on the timing of the initial fungicide application and subsequent applications for managing CLS. The trial was conducted at the University of Minnesota, Northwest Research and Outreach Center, Crookston, MN on a highly tolerant sugar beet variety (Beta vulgaris ‘Crystal 260RR’). Results from this trial will help inform sugar beet growers of the most effective fungicide spray programs for managing CLS.