Strawberry Center Diagnostic Update – Spring 2025

The Strawberry Center’s diagnostic service is on track for another record-breaking year. As of June 15, over 150 plant samples have been submitted for pathogen screening—surpassing the pace of previous years. For comparison, we reached 150 samples in late August of 2024 and received a total of 123 samples throughout all of 2023. This year, 42% of submitted samples are from the Santa Maria district, 28% from Watsonville-Salinas, 25% from Oxnard, and 5% from Northern California.

To date, Fusarium oxysporum f. sp. fragariae race 1 is the most commonly isolated pathogen, present in 21% of samples (Fig 1). This frequency is consistent with previous findings—22% in 2024 and 24% in 2023. We expect to see more Macrophomina as we get into the summer months since it thrives under high temperatures and drought stress.

Join us for our upcoming Field Day on July 24 to receive the latest updates on trends and findings from our diagnostic services!

**Figure 1**. Disease/pathogen identification from diagnostic samples submitted, as of June 2025. A small percentage of samples (~6%) were omitted due to unusual circumstances.

* 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., *Zynthia* *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 for free. 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 Commission Office (3130-3 Skyway Dr suite 305/306, Santa Maria, CA 93455) and the Watsonville Commission Office (180 Westridge Dr #101, Watsonville, CA 95076).

We ask that you ship samples early in the week to ensure they arrive before Friday. If you are dropping off samples, we request that you avoid doing this Thursday after business hours or on Friday to ensure that we process the samples prior to the weekend.