Evaluation of Copper-based Fungicides and Alternative Tank-Mix Partners to Manage Cercospora Leaf Spot in Sugar Beet in Northwest Minnesota, 2025

Cercospora leaf spot (CLS), caused by Cercospora beticola, can cause significant economic loss to sugar beet growers in the mid-western United States. Leaf spots typically appear at the time of row closure, rapidly expand into large necrotic lesions under warm and humid conditions leading to complete defoliations and loss of root and sucrose yield. In this study, we evaluated the efficacy of copper fungicides within a four-spray fungicide spray program for management of CLS. The trial was conducted at the University of Minnesota, Northwest Research and Outreach Center Crookston, MN on a moderately susceptible sugar beet variety (Beta vulgaris ‘Crystal 912RR’). Results from this trial will help sugar beet growers make informed decisions on selecting a copper-based fungicide for managing this CLS.