|Ellis, Margaret - California State University|
|Diaz, Josue - California State University|
|Hutmacher, Robert - University Of California, Davis|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/2019
Publication Date: 8/5/2019
Citation: Ellis, M.L., Diaz, J., Hutmacher, R.B., Ulloa, M. 2019. Genotypic and phenotypic evaluation of Fusarium oxysporum F. sp. vasinfectum race 4 isolates collected from cotton in California. Meeting Abstract. 253-P1.
Technical Abstract: Fusarium oxysporum f. sp. vasinfectum (FOV) race 4 is an aggressive wilt pathogen of cotton that is also capable of causing seedling mortality. FOV race 4, first identified in California in 2001, has been a recurring and expanding threat to California cotton. The goal of this research was to genotype and phenotype current field populations of FOV race 4 in California. A total of 138 isolates were collected from seven commercial or grower fields in the San Joaquin Valley during the 2017 and 2018 growing season. Isolates were genotyped using FOV race 4 specific primers, and DNA sequencing of the translation elongation factor. It was previously believed that FOV race 4 was clonal population in California, however our results identified at least two genotypes. Sixteen representative isolates were evaluated for wilt and seedling capabilities using a rolled towel and root dip inoculation assay, respectively. Plant material for both assays included the FOV race 4-moderately resistant Upland cultivar FM-2334 and susceptible Pima cultivar PHY-830. For the rolled towel assay, seedlings were rated at ten days using a disease severity index and ordinal rating scale. For the root dip assay, plants were evaluated at six weeks for foliar and vascular discoloration symptoms. There was a significant difference among isolate and variety (P<0.0001) in both assays for all data collected. All isolates were able to produce wilt and seedling symptoms on cotton.