Strawberry anatomy: part 3 – leaves and stems
Compared to the flower and the fruit, the anatomy of the strawberry leaf and stems seems like it would be much simpler. But it’s not. To begin with, strawberry leaves are trifoliate, meaning that there are three leaflets for each leaf (Fig. 1). Leaves are connected…
Strawberry anatomy: part 2 – the fruit
We continue this 4-part series on strawberry anatomy by now focusing on the mature fruit. See also, part 1 – the flower. All the structures of the flower are present on the mature fruit, they just look a little different. The calyx is slightly expanded and…
The Lewis Mite Saga Continues
“If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will…
Strawberry anatomy: part 1 – the flower
This is going to be a four-part series on strawberry anatomy. We’ll start with the flower (part 1), move to fruit (part 2) and leaves (part 3) and finish on the crown and root (part 4). Knowing a plant’s anatomy is important because it helps us…
Heated Hole Puncher Ready for Field Use
With beds shaped, dripline installed, mulch laid, and fumigation en route, a strawberry grower’s next concern is when to burn or punch holes before planting. Hole preparation can be time consuming and therefore costly work, requiring large labor crews to accomplish. Using rudimentary tools, a single…
Launch of summer internships with industry partners
The Strawberry Center launched a new summer internship program this year, giving students the opportunity to gain hands-on experience in both applied research and commercial berry production through partnerships within the industry. The program’s first cohort was made up of three current Center student assistants: Shaelyn…
Strawberry Center Field Day, July 24th, 7:30 AM
Join more than 600 strawberry growers, researchers and industry representatives for this year’s Strawberry Center Field Day. Participants will rotate through five stations, hearing from students and staff about the latest research taking place at the Strawberry Center. The event is approved by CDPR and CCA…
When mildew evolves: Understanding strawberry powdery mildew’s secret weapon
Powdery mildew is a common disease that affects strawberries and is caused by a fungus called Podosphaera aphanis. It thrives on dry leaf surfaces when weather is mild (between 60° to 80° F) and humidity is high. What does it look like? Early in its development,…
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…
Current Issues in the Strawberry Industry: 2025 lectures now available
Each year in the Spring academic quarter we invite a series of speakers to Cal Poly to deliver a lecture on a current issue in the California strawberry industry. We just finished this year’s series and thought you might like to see the lineup. All lectures…
Lygus Season 2025
I am so happy to start working on Lygus hesperus this year. The mites took a bite out of me and my lab. It was a mite-y task, but we finished it with all our might and strength. They might have beaten us down, but we…
The race to cool: keeping strawberries fresh postharvest
Quick cooling and maintaining a fruit pulp temperature of 34°F are essential for reducing spoilage and extending the shelf life of strawberries. With recent temperature increases and more on the near horizon, it’s critical to remember: strawberries should be cooled within one hour of harvest. As…
Root-knot nematode diagnostic update
The nematode species most commonly associated with California strawberries is the northern root-knot nematode (N-RKN), Meloidogyne hapla (Fig. 1). At the Strawberry Center’s Disease Diagnostic Service, we observed an increase in submitted samples with root-knot nematodes present. Four of these nematode samples were submitted to the CDFA…
Mites vs Predators vs Adjuvants vs Assumptions
My master’s student Colin Koubek has finished the first phase of a series of experiments examining a selection of fungicides used in 2023 and their interactions with selected adjuvants on the survival of Phytoseiulus persimilis. This effort is part of a larger research project to examine…
Strawberry Commission Hosts Regional Strawberry Grower Meeting in Santa Maria, Friday April 25, 2025
WHEN: Friday, April 25, 2025; 7:30 AM to 2:30 PM WHERE: Santa Maria Fairpark Pavillion; 937 S. Thornburg St., Santa Maria, CA CONTINUING EDUCATION UNITS: 3.5 DPR CEUs hours; 4.5 CCA CEUs hours This is a key strawberry research meeting that brings together the best and…
New UC fungicide efficacy table published
Drs. Adaskaveg, Michailides, and Eskalen of the University of California just published the latest edition of “Fungicides, Bactericides, Biocontrols, and Natural Products for Deciduous Tree Fruit and Nut, Citrus, Strawberry, and Vine Crops in California, 2025.” Center Director Dr. Holmes and Field Research Manager Kyle Blauer…
What causes fruit splitting?
In early Spring, I often observe a problem on fruit that is very dramatic and consistent. It happens almost every year to some degree and is often more severe in certain cultivars/varieties. The incidence of the problem ranges from less than 1% to as high as…
Why don’t we grow strawberries from seed – REVISITED
Back in August 2023, I wrote a blog post titled “Why don’t we grow strawberries from seed.” This blog post became way more popular that I expected (over 58,000 views as of 11 March 2025). One potential reason is this week’s announcement about Ohala’s strawberry consortium…
Prime time for angular leaf spot
We posted last March about angular leaf spot and it’s back this year for a repeat performance. We got about two inches of rain yesterday afternoon and last night. This morning, the angular leaf spot showed so much bacterial ooze that it looked like someone with…
A leopard doesn’t change its spots, but these mites will!
If you search “Lewis mite” or “Eotetranychus lewisi” in google scholar you will find less than 450 scientific papers, but if you type in “two-spotted spider mite” or “Tetranychus urticae” you will find over 119,000 papers. Lewis mites appear to be an under researched pest. This…
Fruit size and catfacing
In case you missed it, Mark Bolda and I co-authored a blog on Mark’s Strawberries and Caneberries blog on Feb 17, 2025. The topic is fruit development as it relates to fertilization and development of the achenes and fruit. Catfacing results when fertilization isn’t uniform but…
Entomology Roadmap 2025
The work is quite feasible, and it is the only thing in our power . . . Let go the past. We must only begin. Believe me and you will see.” -Epictetus, Discourse, 2.19.29-34 Insects and mites unfortunately do not celebrate the holidays, nor do they…
Monarchs on the March and What it Means
If you haven’t heard the news, the monarch butterfly is under consideration for protection as a threatened species under the Section 4(d) of the Endangered Species Act. This journey began with a lawsuit from various environmental groups in 2014 and we are now reaching the finish…
BOOK REVIEW: Yielding Fruit – The Life and Times of Royce S. Bringhurst
Royce S. Bringhurst (Fig. 1) helmed the UC Davis strawberry breeding program from 1953 to 1989, leaving an indelible mark on California agriculture. His biography, written by his son John R. Bringhurst, was published in 2018 and is available for purchase here. This 559-page book, supplemented…
Cal Poly Strawberry Center Diagnostics
As 2024 comes to a close, the Strawberry Center Pathology Lab reflects on all of the projects, grants, and student successes this year. One of the highlights is our ongoing diagnostic plant service provided to California strawberry growers at no fee, funded by the California Strawberry…
Avaunt Lygus!
Disclaimer: This is not an endorsement of Avaunt. The content of this post is meant to be educational. The informed opinion presented here is based off of two trials we completed in Santa Maria using a backpack sprayer and a standard tractor spray. Additional information is…
“Old but Gold”: Meta-analysis shows the value of Captan in strawberries
A team of scientists at the University of Florida, Corteva Agriscience and Syngenta Crop Protection recently published a meta-analysis using data from 25 field trails conducted in Florida from 2005 to 2021. The analysis showed that Captan applications significantly improved marketable yields and reduced Botrytis fruit…
Strawberry Skynet: Artificial general intelligence and integrated pest management in strawberry production
There is only one way to happiness and that is to cease worrying about things which are beyond the power or our will. – Epictetus Artificial Intelligence has gripped the attention of many people in the last two years. If you have held stock in NVIDIA,…
Three lessons from my first Field Day
It’s been nine months since I first began my post as the entomologist at the Strawberry Center, but it seems like two weeks. It has been a blur of activity to develop and run experiments, hire the right people, chug from the firehose, and be able…
Lost in the Suzukii Sauce
Drosophila suzukii, or spotted wing drosophila (SWD) is mother nature’s loving way of reminding us how much she sometimes hates us. SWD can grow on anything. Some growers were hit hard in June of this year in Santa Maria and Oxnard with Drosophila. Processers were rejecting…
Macrophomina’s host range was exaggerated
A paper just published in Phytopathology by Pennerman, Dilla-Ermita and Henry (https://doi.org/10.1094/PHYTO-05-23-0154-R) reports that the host range of Macrophomina phaseolina has been exaggerated for decades. After a critical review of the literature (894 publications to be exact), the authors found that the claim that M. phaseolina…
Current Issues in the Strawberry Industry: 2024 lectures now available
Each year in the Spring academic quarter we invite a series of speakers to Cal Poly to deliver a lecture on a current issue in the California strawberry industry. We just finished this year’s series and thought you might like to see the lineup. Most of…
Beware the temptation of Fraus
The Greco-Romans are the progenitors of much of our culture. Besides aqueducts, lead plumbing, asbestos curtains, and functional forms of government, they had wonderful representations of human flaws. The ancient Roman personification of treachery and fraud was the goddess Fraus. She is depicted in artwork and…
Which soilborne pathogens are most common in California strawberry fields? Part 2 – Santa Maria district
In 2021, an effort began to determine which of the four major soilborne pathogens of strawberry in California – Macrophomina phaseolina, Fusarium oxysporum f. sp. fragariae, Verticillium dahliae, and Phytophthora spp. – are most common. Pathogen surveys of strawberry fields in the three major growing districts…
The Lygus Question
Figure 1. DALL-E generated image from the author’s text input of a Lygus bug pondering his existence while thinking about a strawberry. The Lygus Question is one that has dogged me in my whole career as an entomologist. When I first started working on bush beans,…
Angular leaf spot showing up
We are seeing quite a bit of angular leaf spot (ALS) in our fields and getting some calls about it in other areas of the state. Angular leaf spot is a bacterial disease caused by Xanthomonas fragariae. It typically shows up this time of year when rains…
Beware the storm that delays the Lygus swarm?
“More is lost by indecision than wrong decision.” – Marcus Tullius Cicero Rainfall influences the timing of the Lygus migration. Dr. Peter Goodell, the retired extension super-agent in the Central Valley, wrote that the rainfall extended into spring allows for longer wild host growth which resulted…
JUST PUBLISHED: Fungicide performance against Botrytis fruit rot
The results of two fungicide trials conducted in 2022 and published in Plant Disease Management Reports in 2023 are presented here. In these trials, 20 unique products were evaluated for performance against Botrytis fruit rot (Fig. 1). After 5 weekly applications (Fig. 1), fruit were evaluated…
It’s Botrytis fruit rot season 🙁
Our most economically important fruit disease is Botrytis fruit rot (BFR). BFR thrives under cool, wet conditions. Temperatures between 60F and 75F and wetness lasting over 16 hours are ideal for infection and disease development. These conditions are most likely to occur during the winter and early Spring,…
The Bug Man Cometh
Two months have flown by faster than I realized. Leaving the South and coming back to the West Coast after almost a decade is a bit jarring. Gone are the slow dusty beats of the corn, cotton, and soy tractors traversing the field filled with Ford…
Boom Sprayer Calibration
Boom Sprayer equipment should be calibrated at least once per production season in order to ensure that the correct/desired amount of spray material is being applied. There are six steps to sprayer calibration and regular maintenance: Detailed calibration instructions (video) can be found on the California…
RECENT ASHS PODCAST EPISODE ON CALIFORNIA STRAWBERRIES
The American Society for Horticultural Science has a podcast called “Plants, People, Science”. Take a listen to Episode 7 (The Sweet and the Not-so-Sweet of the U.S. Strawberry Industry) where Gerald Holmes (Strawberry Center, Director) discusses many aspects of the California strawberry industry, including robotics, labor,…
New publication confirms trends in fungicide resistance
A recently published paper in Phytopathology by Naegele et al. adds to the work done by Cosseboom (MS Cal Poly, 2018) with regards to fungicide resistance in Botrytis cinerea in California. Cosseboom’s study was conducted in 2016 and included 888 isolates collected from strawberries throughout the three…
Botrytis and Bees
Wouldn’t it be wonderful if we could get bees to deliver an effective agent to strawberry flowers that would protect them from infection by Botrytis cinerea? Researchers in Sweden (Iqbal et al. 2022; https://doi.org/10.1094/PHYTO-05-21-0205-R) used bumblebees to pick up a biocontrol fungus (Aureobasidium pullulans) and deliver…
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…
What is the most popular strawberry cultivar grown in California?
It depends on what year(s) you’re interested in and if you’re talking about public or proprietary cultivars. For example, if you’re talking about 2022, ‘Monterey’ was the most popular public cultivar, grown on 10,003 acres or 33.4% of the total acreage grown in the state. Proprietary…
Want to learn about the quality of predatory mites you are receiving for your strawberry fields?
We can test the quality of strawberry growers’ predatory mites (BOTH bottles or bean leaves). The freshest predatory mites guarantees the best results! We don’t want the mites to wait in the weather, so contact us the day before the mites arrive to schedule a drop-off…
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…
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