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Poster: Diseases of Plants: New & Emerging Diseases


High diversity in the population of an emerging blackberry pathogen, Fusarium oxysporum.
A. PASTRANA (1), S. Kirkpatrick (1), T. Gordon (1) (1) University of California, Davis, U.S.A.

A wilt disease of blackberry, caused by the soilborne fungus Fusarium oxysporum, has become a more widespread problem in California over the past two years. This emerging pathogen is severely reducing fruit production in affected fields. To improve our understanding of the structure of pathogen population, isolates collected from symptomatic blackberry plants in California and Mexico were evaluated for morphology, pathogenicity and vegetative compatibility. The translation elongation factor 1 alpha (TEF1-α), the intergenic spacer (IGS) and the β-tubulin regions were also sequenced. The combination of TEF1-α, β-tubulin and IGS sequences identified clusters of isolates that corresponded to vegetative compatibility groups (VCGs). A high number of distinct populations were founded both in California and Mexico. However, one VCG included isolates from both countries. No relation was found between VCG and cultivar or geographic origin. Diversity in the pathogen population suggests that the capacity to cause disease on blackberry is not a recent development.