Fusarium species causing Fusarium yellows of sugarbeet.

Species of Fusarium isolated from sugarbeet with Fusarium yellows symptoms from throughout the Western U.S.A. in 2001 were examined for pathogenicity on sugar­ beet in greenhouse tests. Thirteen pathogenic isolates were obtained, of whlch the majority (69%) were F. oxysporum However, four other species were found that caused symp­ toms on sugarbeet that were indistinguishable from Fusarium yellows caused by F. oxysporum f. sp. betae. These included isolates of F. acuminatum, F. avenaceum, F. solani, and F. moniliforme. Of these, only F. acuminatum had previously been reported to cause yellows symptoms on sugarbeet in the United States. The presence of addi­ tional species in sugarbeet has important implications for disease management.