Pathogenic and phylogenetic analysis of Fusarium oxysporum from sugarbeet in Michigan and Minnesota.

Fusarium yellows of sugarbeet (Beta vulgaris), caused by Fusarium oxysporum f. sp. betae, can lead to a significant reduction in root yield, sucrose percentage, and juice purity. Fusarium yellows has become increasingly common in both Michigan and Minnesota sugarbeet production areas, and although genetic resistance provides some control, growers have reported failures when resistant varieties are grown in different parts of the country, potentially due to the variability of local F. oxysporum populations. Previous research has demonstrated that F. oxysporum collected from symptomatic sugarbeet can be highly variable in pathogenicity but that this is not solely due to the wide geographic distribution of sugarbeet production. F. oxysporum isolates were collected from symptomatic sugarbeet throughout the production region of Michigan and Minnesota and were characterized utilizing pathogenicity and phylogenetic analysis. The F. oxysporum population from Michigan and Minnesota was found to be variable in pathogenicity to sugarbeet and was polyphyletic. Therefore, the population from Michigan and Minnesota could not be classified into distinct races, but rather was adequately described by three previously reported phylogenetic clades. Additional