Historically, Fusarium oxysporum f. sp. fragariae (Fof), the causal agent of Fusarium wilt in strawberry, has been a major problem for strawberry production in California, but has been largely absent in the rest of the United States. During the growing seasons of 2023-2025, independent detections of Fof were made on strawberry plants exhibiting symptoms of Fusarium wilt in the eastern U.S. states of Florida, North Carolina, New York, Connecticut, and Virginia. Sixteen isolates were obtained from symptomatic plants across this region and a subset (n=14) were confirmed to be Fof by pathogenicity testing, morphological characterization, PCR diagnostics, and whole-genome sequencing. Specifically, these tests demonstrated that all tested isolates were virulent on susceptible (fw1) strawberry cultivars but not on resistant (FW1) cultivars, classifying them as race 1. While all isolates tested positive with the more recently developed Fof-specific PCR assay by Burkhardt et al. (2019), many (43.75%) failed detection with the commonly used Suga et al. (2013) assay. Comparative genomics revealed that these isolates represent at least three distinct phylogenetic clades (Y1, Y2, and the putative Y10), suggesting multiple independent introductions rather than a single dissemination event. The genetic diversity of the eastern U.S. Fof populations and their likely origin from nursery stock highlight the need for more robust diagnostics, certified clean planting stock, and region-specific resistance trials to manage Fusarium wilt beyond California.
Westrick et al. (2026) studied this question.