The oak trees get infected in the trunk and die over a two to three-year period, she said.
The tree that spreads SOD to the oaks is the bay laurel, which can grow beside and at times become intertwined with the oaks, said Matteo Garbelotto, director of the University of California at Berkeley's Forest Pathology and Mycology Lab.
During the Blitz, community members go out into the oak forests and take leaf samples from bay laurel trees that carry the SOD microbe. The leaves are then sent to the lab to find out if the samples show evidence of SOD.
Last year, the infection rate for trees sampled in the south Peninsula area was the highest out of 18 participating areas in Northern California at 19.1% for the 88 trees that were sampled, according to the results from the lab.
"The way to slow down the disease is to find a way to reduce the number of bay laurel," Garbelotto said. "Also, if we can increase the distance between the oaks and the laurel, the range that the disease can spread goes down."
The infection rate for oaks within 15 feet of a bay laurel is about 75%, he said. After a distance of about 20 yards, the infection rate drops substantially.
The infected oaks can fall down when they are still green, potentially on top of a house or a car, Garbelotto said.
"If an infected oak is near your house, you want to take it out because if it burns in a fire it will spread to your home," he said.
Garbelotto will also be presenting an update on infestations around the Bay Area and will also discuss new treatment and disease diagnostic options and the discovery of outbreaks in areas previously thought to be uninfested.
Garbelotto was on the team that first isolated the microbe that causes SOD.
The team found that the pathogen originated in ornamental plants that had arrived from Asia, including rhododendrons and camellia, and escaped into the larger environment, he said.
The phenomenon happened first in California, but there have also been recent SOD outbreaks in England, Belgium, Holland, Ireland, France and southern Oregon, he said.
In San Mateo County, the SOD infections, carried by bay laurel and tan oaks, move through the ridge top of the Santa Cruz Mountains and then east down the hill through Woodside and Portola Valley to urban areas, where the temperature is warmer and the severity of the infections decreases, Garbelotto said.
The blitz results meeting will begin at 7 p.m. at Independence Hall, 2955 Woodside Road.
For more information, contact Woodside Town Manager Kevin Bryant at (650) 851-6790 or [email protected], or Portola Valley Assistant Town Manager Brandi de Garmeaux at (650) 851-1700, ext. 222 or [email protected]
This story contains 520 words.
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