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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #402019
Research Project: Disease Management and Improved Detection Systems for Control of Pathogens of Vegetables and Strawberries

Location: Crop Improvement and Protection Research

Title: First report of Fusarium oxysporum f. sp. fragariae race 2 causing Fusarium wilt of strawberry (Fragaria × ananassa) in California

Author
item DILLA-ERMITA, CHRISTINE - University Of California
item Goldman, Polly
item Jaime, Jose
item Ramos, Gerardo
item PENNERMAN, KAYLA - Oak Ridge Institute For Science And Education (ORISE)
item Henry, Peter

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2023
Publication Date: 8/23/2023
Citation: Dilla-Ermita, C.J., Goldman, P.H., Jaime, J., Ramos, G., Pennerman, K., Henry, P.M. 2023. First report of Fusarium oxysporum f. sp. fragariae race 2 causing Fusarium wilt of strawberry (Fragaria × ananassa) in California. Plant Disease. 107. Article 2849. https://doi.org/10.1094/PDIS-02-23-0217-PDN.
DOI: https://doi.org/10.1094/PDIS-02-23-0217-PDN

Interpretive Summary: Many strawberry varieties/cultivars are genetically resistant to the Fusarium wilt disease, which is caused by the fungal pathogen Fusarium oxysporum f. sp. fragariae (Fof). For example, Portola, Victor, and San Andreas are Fusarium wilt-resistant varieties from the University of California. These varieties have the same Fusarium wilt resistance gene called Fw1. Until now, this gene was effective against all strains of the Fusarium wilt pathogen, called Fof race 1, in California. The Henry Lab at the USDA-ARS just discovered a strain of Fof that causes disease on varieties with the Fw1 resistance gene (including: Portola, Victor, and San Andreas). This new strain, called Fof race 2, was isolated from diseased plants at a Portola summer-planted field in Oxnard. The distribution of affected plants in the field suggests this Fof race 2 strain was already in the soil and did not arrive with transplants. Furthermore, plants from the same nursery field are healthy in other, nearby areas. Efforts are ongoing to determine if Fof race 2 is present in any other fields in the area and to develop management recommendations for fields infested with race 2.

Technical Abstract: In fall of 2022, a high level of disease severity was observed at a summer-planted, organically farmed strawberry field near Oxnard, California. Symptoms included asymmetrical foliar chlorosis, which is typically associated with Fusarium wilt. However, the cultivar Portola was being grown, and this cultivar has the FW1 gene conferring resistance to Fusarium oxysporum f. sp. fragariae race 1. Abundant F. oxysporum mycelia grew from surface sterilized petioles plated on Komada’s medium. Pure cultures from these petioles caused foliar chlorosis, severe wilting, and mortality on cultivars with the FW1 resistance gene (cv. Fronteras and cv. San Andreas) and susceptible controls (cv. Monterey). These results are the first report of F. oxysporum f. sp. fragariae race 2, which can cause disease on FW1 cultivars, in California.