Mediterranean oak borer threatens Sonoma County’s white oaks
An invasive beetle is killing Sonoma County’s white oaks, and the pace alarms people who watch our forests. “Jeannie Chin had sent us an invitation to a Zoom meeting and I went and it is terrifying,” said conservationist Jill Beckler after a webinar on Mediterranean oak borer.
Also called MOB, the tiny ambrosia beetle bores into valley and blue oaks and can kill a tree within a year or two. A forester who spoke at the webinar, Matt Banquero, said he “has seen thousands of trees killed.”
What it looks like on the ground
Early damage often appears in the canopy. “It hits the top of the tree and may cause flagging or dieback or sparseness,” Beckler said. Once symptoms appear, decline can be swift. “And then depending on the season, the tree will die either that year or the following year.”
Until recently, many assumed the problem was localized. Beckler thought it was confined to the Laguna de Santa Rosa and said she hadn’t noticed dead trees along Todd Road. “But apparently it’s terrible,” she said. Her summary for Sonoma County: “So it’s bad, and it’s here.”
Containment is key
There is no quick fix for a tree already under attack, Beckler said. The immediate goal is to keep the beetles from spreading. “The only advice seemed to be to tarp the wood,” she said — a practical step to keep adult beetles from flying out of cut material. “They’re already in the wood by the time you cut your tree down,” she added…