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Deadly tree disease, sudden oak death, found in the Presidio

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Sudden oak death has been found in the Presidio for the first time, but is thought to be an isolated case, a scientist investigating the occurrence said Tuesday.

Presidio workers made the discovery in October at a location near Pacific Heights, but only recently were scientists able to confirm it hadn’t spread to surrounding trees, according to Dr. Matteo Garbelotto of the Forest Pathology and Mycology Laboratory at UC Berkeley.

Garbelotto said the 25-foot coast live-oak tree was “bleeding” a “viscous sap,” which is associated with trying to fight off sudden oak death. It was thought to have been infected in 2006 during a rainy spring season that helped spores spread the pathogen, he said.

The disease also appeared briefly several years ago in Golden Gate Park. The Presidio is home to between 200 and 300 native coast live oaks.

“I don’t think this is the beginning of a disaster,” Garbelotto said, adding that the oaks themselves do not have spores and thus cannot spread the disease. “Locally, I think we are OK, but I am really more concerned on a national level.”

Sudden oak death is not native to North America and is believed to spread through ornamental plants, and in the wild via bay laurel trees. Since it was first discovered in California, millions of trees have died, according to Garbelotto.

“It’s the most serious disease of forests in the world,” he said.

Genetic testing indicates that the particular strain affecting the Presidio tree likely came from an ornamental plant in a nearby garden outside the Presidio, according to Garbelotto.

Presidio officials and lab staff are working to spread the word among local homeowners.

aburack@sfexaminer.com