New publication confirms trends in fungicide resistance

Figure 1. Botrytis fruit rot often starts beneath the calyx where moisture can get trapped, along with petals, where it will persist long enough for the pathogen to germinate and infect the fruit. (photo by G. J. Holmes) A recently published paper in Phytopathology by Naegele et al. adds to the work done by Cosseboom … Continue reading New publication confirms trends in fungicide resistance

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 it to strawberry flowers, reducing Botrytis fruit rot by … Continue reading Botrytis and Bees

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 cultivars are those held by private companies such as … Continue reading What is the most popular strawberry cultivar grown in California?

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 by twice weekly fungicide applications in FL.  No negative … Continue reading New publication reports efficacy of UV-C against powdery mildew in FL and CA

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 in temperature and relative humidity or to filtering UV … Continue reading Tunnel plastics, UV and powdery mildew

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 name TELONETM) as an effective nematicide with minor efficacy … Continue reading New research shows 1,3-D is effective against Macrophomina

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 were done using live plant tissue (Fig. 2). This … Continue reading RECENTLY PUBLISHED: Fungicide resistance in strawberry powdery mildew in California

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 to see a variety of deformed fruit and blackened … Continue reading Frost injury

JUST PUBLISHED: Strawberry host plant resistance to powdery mildew

The author (Michael Palmer) in a strawberry field in Santa Maria, CA. Photo by G. J. Holmes 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 … Continue reading JUST PUBLISHED: Strawberry host plant resistance to powdery mildew