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Sudden oak death persists locally

Submitted by Ted Haynes of the Atherton Tree Committee.

Results of the 2012 survey of sudden oak death (SOD) infection, conducted by volunteers throughout the Bay Area, show the disease persists on the Midpeninsula. Of the trees sampled, infection rates were 15.7 percent in Woodside, 14 percent in Portola Valley, and 3.2 percent in Atherton.

Visit matteolab.org for more information on the results from the UC Berkeley Forest Pathology and Mycology lab.

Dr. Matteo Garbeletto, head of the lab, will conduct community meetings to present the survey results. For Woodside, Portola Valley, and Emerald Hills, the meeting will be held at the Woodside Town Hall, 2955 Woodside Road in Woodside, at 7 p.m. Friday, Oct. 26.

For Atherton and Los Altos, the meeting will be at the Los Altos Town Hall, 26379 Fremont Road in Los Altos, at 6 p.m. Friday, Nov. 2.

Field meetings to discuss SOD management and demonstrate treatment will be held at 1:30 p.m. Saturday, Oct. 27, at Portola Valley Ranch and at 10 a.m. Sunday, Nov. 3, at the Oak Grove Picnic Area in Foothills Park, 3300 Page Mill Road in Los Altos Hills.

Year-to-year comparisons and interpretation of survey results will require Dr. Garbeletto's expertise because the specific trees sampled vary from year to year and, in some cases, residents have removed both infected and uninfected trees.

In Atherton for example, three out of 19 trees sampled in 2010 were infected (16 percent infection rate), six out of 41 trees were infected in 2011 (15 percent), and only one of 31 trees was infected in 2012 (3 percent).

The pathogen that causes sudden oak death, Phytophthora ramorum, can infect 107 different plants, including camellias and rhododendrons. Most plants survive but some, especially bay laurels, spread the disease to oaks.

The annual survey, known as the "SOD Blitz," focuses on California bay laurels in order to best measure the spread of the disease. Once infection is detected in an oak, it is generally too late to save the tree.