US: Angular leaf spot troubles California strawberry growers

Fresh Strawberry

Fruits

United States

Sustainability & Environmental Impact

Published Mar 24, 2024

Tridge summary

The Cal Poly Strawberry Center has reported an increase in angular leaf spot (ALS), a bacterial disease affecting strawberry fields. ALS, caused by Xanthomonas fragariae, is spread by water and thrives at around 68º F. It can be identified by 'windows' in the leaves and a gummy bacterial ooze. While existing infections cannot be cured, the disease can be managed by allowing plants to recover under drier conditions and using three specific products to prevent future spread. The susceptibility of different strawberry cultivars to ALS varies, but more data is needed.

Disclaimer: The above summary was generated by a state-of-the-art LLM model and is intended for informational purposes only. It is recommended that readers refer to the original article for more context.

Original content

Editor’s note: This is a post from the Cal Poly Strawberry Center’s blog, written by Gerald Holmes, director of the center, and Shashika Hewavitharana, assistant professor and strawberry plant pathologist. 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 are more frequent. The optimum temperature of the pathogen is ~68º F and it is known to be killed above 90º F. The splashing water will spread the pathogen to wherever the splashing takes it. You can diagnose this disease easily in the field. Look for the “windows” in the leaves when held up to a bright light/sun (picture 1). On a dewy morning, the lesions will show bacterial ooze that looks gummy when wet and shiny (like lacquer) when dry (picture 2). The most effective way to manage this disease is preventing it from getting ...

Source: Fruitgrowersnews