The Strawberry Center’s diagnostic service has experienced another record breaking year for samples received. Between Jan 1 and Dec 31, 2025, 411 samples were submitted for pathogen detection. For comparison, there were 201 and 132 samples in 2024 and 2023, respectively. This year, 51% of submitted samples were from the Santa Maria district, 27% from Oxnard, 16% from Watsonville-Salinas, and 6% from Northern California.
To date, Fusarium oxysporum f. sp. fragariae race 1 is the most commonly isolated pathogen, present in 25% of the samples submitted in 2025 (Fig 1) with Macrophomina phaseolina closely behind at 23%. Co-infection with at least two major or minor pathogens occurred in 25% of samples. In addition to our standard pathogen detection, 10 plant samples were selected at random and sent to Tri-Cal Diagnostics to compare results. Results from Cal Poly were in 100% agreement with the results from TriCal Diagnostics.
Figure 1. Disease/pathogen identification from diagnostic samples submitted, from Jan 1 to Dec 31, 2025.
* Indicates pathogens that are not known to be solely pathogenic to strawberry.
**Samples are screened for Fusarium oxysporum f. sp. fragariae races 1 and 2, Macrophomina phaseolina, Phytophthora sp., Pythium sp., Verticillium dahliae, Colletotrichum sp., Zythia fragariae, Neopestalotiopsis sp., Cylindrocarpon sp., Rhizoctonia solani, Botrytis cinerea, Xanthomonas fragariae, and Meloidogyne sp.
How to submit a sample
Any strawberry grower can submit a plant sample to our lab free of charge. We request that your sample consist of 4 to 6 plants that are symptomatic, but not fully necrotic (dead). Samples should come in a sealed plastic bag with the completed submission form attached (https://strawberry.calpoly.edu/strawberry-disease-information-form). Samples can be dropped off or shipped to our office (Cal Poly Strawberry Center, 1 Grand Ave, Building 83, STE 1B, San Luis Obispo, CA 93407). In addition, there are drop off locations at the Santa Maria Strawberry Commission Office (3130-3 Skyway Dr suite 305/306, Santa Maria, CA 93455) and the Watsonville Strawberry Commission Office (180 Westridge Dr #101, Watsonville, CA 95076). We ask that if you ship or drop off a sample off-site, you avoid doing so on Fridays.
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Wondering if strawberry growers submit clinic sample that turn out to be abiotic. Some clinics receive 25-35% of samples that are non-pathogenic disorders or injury.
Indeed. About 25% of the samples end up testing negative for any of the 4 major soilborne pathogens. We do not receive many foliar samples which is a part of the plant subject to many and varied abiotic disorders.
We get plenty of samples where the causal agent is not determined – something like 20-25% of samples. These are suspected to be either abiotic in cause or plant sample was inadequate in some way.