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…
FW1-resistant varieties with Fusarium wilt in Oxnard, CA
Some strawberry varieties are genetically resistant to the Fusarium wilt disease. For example, Fronteras, Portola, and San Andreas are Fusarium wilt-resistant varieties from the University of California. A description of disease resistance for currently available varieties is on the California Strawberry Commission web site. All Fusarium wilt-resistant…
New publication reports efficacy of UV-C against powdery mildew in FL and CA
A recent publication by Mello et al. reports that strawberry powdery mildew (SPM) was reduced by nighttime application of UV-C to field plots at 200 J m-2 . Disease reduction was equivalent to that provided by weekly fungicide applications in CA and superior to that provided…
Insect pest management in strawberries: A closer look at the IPM toolbox
Insect pest management in strawberries: A closer look at the IPM toolbox, Sarah Zukoff
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…
A bumper crop of lygus: 7 facts about lygus bugs you may not have known
This summer we’ve experienced high levels of lygus infestation, especially in the Santa Maria and Oxnard growing districts. It’s a good time to review some basic lygus biology. 1. There are 19 species of Lygus in California; however, only two species can be regularly found in…
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)…
New research shows 1,3-D is effective against Macrophomina
A new publication by Baggio et al. (2022) out of the University of Florida provides evidence that 1,3-dichloropropene (1,3-D) alone and in mixture with chloropicrin were more effective in reducing inoculum of Macrophomina phaseolina than chloropicrin alone. We generally think of 1,3-D (known under the trade…
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”…
Predatory mite bottle counts for 2021-2022 update: Spider mite biocontrol in California strawberries: Part 2
Strawberry growers requested quality checks on the predatory mite products they were buying since they felt the numbers promised on the label did not always match the number of live mites they actually received. Here I summarize the samples we have received so far from January…
What can we learn from Macrophomina in chickpea?
It’s helpful to look at similar systems to learn more about your own. For example, we can learn a lot about Macrophomina in strawberries by looking at the diseases this fungus causes in many other crops where it has been studied more intensively. A recent paper…
JUST PUBLISHED: Fungicide performance against powdery mildew, 2021
The results of two powdery mildew fungicide trials conducted in 2021 were just published in Plant Disease Management Reports. In these trials, 17 unique products were evaluated for performance against powdery mildew under greenhouse conditions (Fig. 1). Weekly disease incidence and severity was assessed one day…
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…
JUST PUBLISHED: Fungicide performance against Botrytis fruit rot 2021
The results of two fungicide trials conducted in 2021 were just published in Plant Disease Management Reports. In these trials, 20 unique products were evaluated for performance against Botrytis fruit rot (Fig. 1). After 5 applications (Fig. 2), fruit were evaluated in the field (at-harvest) and…
Lygus bug insecticide mortality bioassays: A preliminary look at 2021 results
Lygus bugs are starting to find their way from drying weeds on the hillsides to our beautiful blooming strawberry fields in the Santa Maria area about two weeks earlier than normal. Several fields have already been sprayed or are planning to be sprayed soon. As growers…
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…
An Automated Harvesting Update: Harvest CROO Robotics, Traptic, and Advanced Farms
Harvest costs represent over 70% of operating costs/acre to produce strawberries in California (UC Davis Cost Study, 2021). With the passing of SB-3 minimum wage increase requirements in 2016, the California Strawberry Commission has recognized labor-saving automation as the industry’s leading research priority. By 2018, there…
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…
JUST PUBLISHED: Strawberry host plant resistance to powdery mildew
Michael Palmer finished his master’s thesis last winter and his second paper just appeared in the journal Plant Health Progress (https://doi.org/10.1094/PHP-12-20-0101-RS). This paper works out the methods for screening strawberry cultivars for their susceptibility to powdery mildew caused by Podosphaera aphanis. Michael screened 10 strawberry cultivars…
“How many predatory mites are in there?” Spider mite biocontrol in California strawberries: Part 1
Many strawberry growers in California have happily embraced biological control to help them manage their ever-growing spider mite populations in both their organic and conventional fields by releasing commercially grown predatory mites (PM). However, some have expressed concern over the control they are seeing (Fig. 1)…
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…
Strawberry Center BLOG 