Which soilborne pathogens are most common in California strawberry fields? Part 1 – Watsonville/Salinas district

In the California strawberry industry, it’s widely accepted that there are four major diseases caused by soilborne pathogens: Macrophomina root rot (caused by Macrophomina phaseolina) (Fig. 1), Fusarium wilt (caused by Fusarium oxysporum f. sp. fragariae), Verticillium wilt (caused by Verticillium dahliae), and Phytophthora crown and…

Cal Poly Strawberry Center’s Field Day is Aug. 3

Only six weeks away! Join more than 400 strawberry growers, researchers and industry representatives for this year’s Strawberry Center Field Day. Participants will rotate through stations, hearing from Cal Poly students and staff about the latest research taking place at the Strawberry Center. Topics include the…

Spider mites in saturated strawberry fields

Twospotted spider mites prefer lower humidity, yet they are reproducing and even thriving in some strawberry fields with flooded furrows, even right now after the historical rain storms. Although the flooding causes higher humidity in the field overall, the microclimate around the plant is still hospitable…

Highest rainfall in 18 years

The much-needed rainfall this year has already exceeded annual rainfall for the previous 18 years and we still have two months to go before we’re out of our normal wet season. As of January 17, 2023 rainfall for the current Water Year (measured from July 1…

Grower/PCA Round Table: Santa Maria Lygus Bug discussion summary

A small round table meeting was hosted by the California Strawberry Commission (CSC) in Santa Maria to help mediate a discussion on concerns of high lygus bug populations (Fig. 1). Both Cal Poly Strawberry Center (CPSC) and the California Strawberry Commission spoke on issues related to…

Cal Poly Strawberry Center Disease Diagnostic Service

About the plant disease diagnostic service Soil-borne pathogens such as Macrophomina phaseolina are challenging strawberry production as they become increasingly prevalent across California (Fig. 1). Accurate disease diagnosis is the cornerstone of integrated pest management. The Strawberry Center’s disease diagnostic service has been serving California strawberry…

Off-cycle Zythia leaf blotch

We usually see Zythia leaf blotch (caused by Zythia fragariae) during the early spring when plants are small and the weather is cool and wet. With summer planting in Santa Maria occurring in May, especially in fields close to the coastline where fog and heavy dews…

Tunnel plastics, UV and powdery mildew

In the vast majority of seasons, powdery mildew (PM) (caused by Podosphaera aphanis) is the most economically important foliar disease of strawberries in California. Many growers have observed that PM is particularly destructive in glasshouses and under plastic tunnels. This could be due to the difference…

Why don’t we grow strawberries from seed?

Virtually all strawberry plants grown to produce fruit were planted as a transplant. Transplants take on many forms, but in California we use bareroot transplants (Fig. 1). Why not use seeds instead? Those little things on the outside of every strawberry fruit are seeds encased in…

Salt marsh caterpillar damage in strawberries

The salt marsh caterpillar is a common species which feeds on many different species of plants and can be found sporadically on strawberries throughout the year. The defoliation can be quite dramatic in spots when several egg masses hatch at once and the larvae start to…

SWD parasitoid releases!

Spotted wing drosophila, Drosophila suzukii (SWD), will have a new natural enemy to contend with in the Salinas and Santa Maria growing regions. After ten years of research by a determined group of entomologists to find a better parasitoid for SWD, Ganaspis brasiliensis (Gb for short)…

Root-Knot Nematode in Strawberry

Do you know how to diagnose root-knot nematode in strawberry? We recently came across a rare occurrence of root-knot nematodes in two samples submitted to the Strawberry Center’s Disease Diagnostic service. The samples were both from the Santa Maria district and were both positive for root-knot…

Rhizopus rot or “leak”

June is here and temperatures are rising. Along with rising temperatures comes a shift in fruit rotting fungi from Botrytis to Rhizopus (Fig. 1). Rhizopus stolonifer causes Rhizopus rot or “leak”. The term “leak” comes from how the fruit are liquified by the fungus and “leak”…

RECENTLY PUBLISHED: Fungicide resistance in strawberry powdery mildew in California

Strawberry powdery mildew caused by Podosphaera aphanis, is an important disease in California strawberries (Fig. 1). Strawberry Center master’s student Michael Palmer recently published his work on fungicide resistance in the journal Plant Disease (https://doi.org/10.1094/PDIS-12-20-2604-RE). Because P. aphanis is an “obligate parasite” all of the experiments…

Classic Botrytis data from 1987

A lot of people never heard the word “epidemic” (the rapid spread of a disease), “pandemic” (spread of a disease over a wide area) or “epidemiology” (the study of how disease spreads) until the COVID pandemic. Plant pathologists have been trying to figure out what drives…

Bronzing caused by frost

In my last post, I showed a bunch of photos of frost injury. Later I noticed another effect: Bronzing (Figs. 1, 2 & 3). Just like misshapen fruit can be caused by damage to the developing flower parts, bronzing can result from damage to the epidermal…

Disease diagnostic lab updates

Here’s an update on the Cal Poly Strawberry Center’s Disease Diagnostics. A total of 16 samples have been submitted so far of which 11 have been diagnosed with the pathogens in (see Table below). Relative to this time last year we are seeing more samples positive…

Frost injury

Recent frosts at the Cal Poly farm has brought frost injury in all its variety. According to the Compendium of Strawberry Diseases “frost injury is probably the most common non-pathogen related and non-insect-related disorder affecting strawberry flowers and fruit.” Whenever temperatures dip to below freezing, expect…

Let’s get started!

Welcome to the Cal Poly Strawberry Center BLOGThis idea started at our 2021 Field Day where almost 100 growers and PCAs signed up to receive research updates from the Strawberry Center. We added another 180 people to the list since then. We’re glad you’re here and are excited…