Fungicide Rotations and Host Resistance for Cercospora Leaf Spot Management in Sugar Beet
ISSN 2158-9429
Volume 18, Issue 2 - December 2025
Editor: Bindu Poudel-Ward
Abstract
Cercospora leaf spot (CLS), caused by Cercospora beticola, is a major foliar disease of sugar beet in North Dakota, Minnesota, and other regions with warm, humid conditions. Intensive fungicide use has driven resistance development across multiple fungicide classes, reducing control efficacy. This study evaluated rotations and mixtures of single- and multi-site fungicides for CLS management. Field trials (2023–2024) in North Dakota and Minnesota tested two sugar beet varieties, one resistant and one susceptible to CLS. Treatments included triazoles, QoI + triazole premix, and multi-site protectants (tin, copper, mancozeb). Both variety and fungicide treatment significantly affected disease severity. Resistant varieties consistently had the lowest disease severity, while in susceptible varieties, rotations achieved control comparable to mixtures. These findings highlight the importance of integrating resistant germplasm with fungicide rotation to sustain CLS management and mitigate fungicide resistance risk.
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