Michigan is the second-largest producer of dry beans in the United States. Among the yield-limiting diseases dry bean production faces is Fusarium root rot, which can lead to decreased nutrient and water uptake, plant stress, and even plant death. Cultural control can manage root rot, however tolerant cultivars or seed treatments may be more effective, especially if common casual agents are known. To understand which species of clade 2 of the Fusarium solani species complex (FSSC) were causing Fusarium root rot in Michigan, a survey was conducted revealing 50% of samples collected to be F. cuneirostrum, 37% F. brasiliense, and 13% as F. phaseoli. Isolates collected were moderately to highly pathogenic on two cultivars of dry beans. Isolates representative of both MAT idiomorphs were detected. An inoculated field trial was conducted to determine pathogenicity of F. brasiliense and F. virguliforme on two dry bean cultivars in the field. F. brasiliense decreased stand and dry plant mass while both pathogens increased root rot. Using two qPCR assays revealed the colonization potential of F. brasiliense in taproots to be greater than that of F. virguliforme. Two seed treatments were also examined as means of F. brasiliense management on dry beans. A seed treatment containing fluopyram reduced the quantity of F. brasiliense in the taproots of both cultivars though neither seed treatment influenced yield. Greater understanding of the Fusarium root rot pathogens present in Michigan and the efficacy of seed treatments can improve dry bean production.
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