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 … Continue reading Tunnel plastics, UV and powdery mildew
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 … Continue reading Why don’t we grow strawberries from seed?
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 … Continue reading Salt marsh caterpillar damage in strawberries
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) … Continue reading SWD parasitoid releases!
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 … Continue reading New research shows 1,3-D is effective against Macrophomina
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 … Continue reading Root-Knot Nematode in Strawberry
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” … Continue reading Rhizopus rot or “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 … Continue reading Predatory mite bottle counts for 2021-2022 update: Spider mite biocontrol in California strawberries: Part 2
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 … Continue reading What can we learn from Macrophomina in chickpea?
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 … Continue reading JUST PUBLISHED: Fungicide performance against powdery mildew, 2021
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 … Continue reading RECENTLY PUBLISHED: Fungicide resistance in strawberry powdery mildew in California
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 … Continue reading Classic Botrytis data from 1987
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 … Continue reading JUST PUBLISHED: Fungicide performance against Botrytis fruit rot 2021
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 … Continue reading Lygus bug insecticide mortality bioassays: A preliminary look at 2021 results
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 … Continue reading Bronzing caused by frost
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 … Continue reading Disease diagnostic lab updates
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 … Continue reading An Automated Harvesting Update: Harvest CROO Robotics, Traptic, and Advanced Farms
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 … Continue reading Frost injury
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 … Continue reading JUST PUBLISHED: Strawberry host plant resistance to powdery mildew
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) … Continue reading “How many predatory mites are in there?” Spider mite biocontrol in California strawberries: Part 1
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 … Continue reading Let’s get started!