March 29, 2024
'Scariest tree pathogen in the world' spreading rapidly in California
BERKELEY - Sudden Oak Death (SOD), a deadly disease for oak trees, is on the rise in California. According to a survey conducted by UC Berkeley scientists, the number of infected trees has almost doubled since 2018.

Matteo Garbelotto, the director of the UC Berkeley Forest Pathology and Mycology Laboratory, has been involved in conducting the survey of 14 California counties (stretching from Humboldt to Monterey) for the past 12 years. This year, two aspects of the results stood out to him.

"We found this year the most sharp increase ever in the number of trees affected," Garbelotto told SFGate.com. However, this was expected due to the wet winters we've had in California for the past two years — the spores spread faster with significant rainfall.

What was really unexpected was the scope of where they were finding the outbreaks.

"I saw a lot of outbreaks that we had seen before in the 12 years of our program, but I saw all the outbreaks being expressed at once this year," he said. In previous years, some outbreaks would decrease while others would flare up — this year, every outbreak flared up. "This patterns shows me that the organism has really spread into the ecosystem of Coastal California. Now it's already established everywhere, and it flares up when the weather is favorable.
Story Date: December 8, 2019
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