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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #399252
Research Project: Disease Management and Improved Detection Systems for Control of Pathogens of Vegetables and Strawberries

Location: Crop Improvement and Protection Research

Title: Sporodochia formed by Fusarium oxysporum f. sp. fragariae produce airborne conidia and are ubiquitous on diseased strawberry plants in California

Author
item Henry, Peter
item DILLA-ERMITA, JADE - University Of California
item Goldman, Polly
item JAIME, JOSE - California State University
item Ramos, Gerardo

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2023
Publication Date: 9/1/2023
Citation: Henry, P.M., Dilla-Ermita, C.J., Goldman, P.H., Jaime, J., Ramos, G. 2023. Sporodochia formed by Fusarium oxysporum f. sp. fragariae produce airborne conidia and are ubiquitous on diseased strawberry plants in California. Phytopathology. 113(8):1399-1404. https://doi.org/10.1094/PHYTO-10-22-0375-SC.
DOI: https://doi.org/10.1094/PHYTO-10-22-0375-SC

Interpretive Summary: Fusarium wilt of strawberry is an economically damaging disease caused by a fungus, Fusarium oxysporum f. sp. fragariae. This fungus was previously thought to only move to new locations on infested soil or plants. This work demonstrates for the first time that F. oxysporum f. sp. fragariae can also move to new fields with airborne spores. The airborne spores are produced by a fungal growth called a ‘sporodochium’, which can proliferate on dead, above-ground parts of the strawberry plant. The sporodochia were found in 21 out of 24 Fusarium wilt-diseased fields and were present on almost every plant where discovered. Sporodochia produced by F. oxysporum f. sp. fragariae are apparently very common and present a new obstacle to control and containment of this damaging pathogen.

Technical Abstract: Sporodochia are dense masses of fungal hyphae bearing asexual conidia. For Fusarium oxysporum, sporodochia are known to produce airborne conidia and enhance the dissemination of this otherwise soilborne pathogen. Sporodochia are small and transient, and they are documented for only a few formae speciales of Fusarium oxysporum. This study reports sporodochia produced by F. oxysporum f. sp. fragariae, the cause of Fusarium wilt of strawberry, in the Monterey Bay region of California. Sporodochia were consistently present in Fusarium wilt-afflicted strawberry fields and were discovered in 21 of 24 Fusarium wilt-diseased fields. Only necrotic tissues were observed bearing sporodochia, and they were most frequently observed on petioles and peduncles. Sporodochia grew significantly longer up peduncles than petioles, extending further away from the base of the plant and toward parts of the canopy more subject to wind dispersal. A stolon hosted the longest stretch of sporodochia growth, along its entire 35 cm length and on the base of the daughter plant. Macroconidia were produced by all sporodochia samples, and we did not find microconidia on any samples. An initial series of experiments confirmed the potential for sporodochia to disperse conidia over short distances. The prevalence of sporodochia producing airborne spores of F. oxysporum f. sp. fragariae has great importance for disease management and biosecurity.