In a breakthrough in the study of sudden oak death, scientists at the University of California at Berkeley now have reliable guidelines on inhibiting the spread of the disease.
After a seven-year test involving 128 locations in Santa Cruz County woodlands, the scientists determined that creating an area around the oak tree that is free of California bay laurel (Umbellularia californica) trees, a prominent host of the pathogen, can be effective in preventing infection.
And in a bid to enlist more citizen scientists in the battle against sudden oak death, a free application was created for tablet computers and iPhone and Android smart phones. The SODmap Mobile App shows users the locations of infected oak trees and provides estimates on the risk of infection to nearby vulnerable oaks.
These recent developments came to the attention of the Almanac in connection with a hike arranged by the Midpeninsula Regional Open Space District for a group of about 80 scientists from around the world who were in the Bay Area for a sudden-oak-death symposium at UC Berkeley.
Organizing the symposium was a UC Berkeley scientist well known to Woodside and Portola Valley participants in sudden oak death tree-sampling weekends, or blitzes: Matteo Garbelotto, an adjunct professor in environmental science and a specialist in forest pathology and the study of fungi.
This reporter accompanied Dr. Garbelotto, employees from the open space district, and symposium scientists who had traveled by bus to the Los Trancos Open Space Preserve in the hills above Palo Alto. After a brief hike into the woods and an hour or so of talk about the status of the fight against the disease in the presence of the upright remains of an oak that the disease killed, the group decamped for a visit to the forests associated with the Crystal Springs Reservoir.
Caring for oaks
Scientists first detected sudden oak death in California in 1995, and since then the pathogen that carries the disease has killed millions of trees. Among the vulnerable species are California coast live oaks, canyon live oaks, black oaks, and tanoaks.
The effort by scientists to determine exactly what leads to a tree becoming infected has taken some time. The experiment was "quite complex," Dr. Garbelotto said. In a nutshell, he said, over seven years, scientists monitored events that could lead to infection and learned that it is "extremely rare" in dry years, that it can be more frequent in wet years, and that it depends on the density of bay laurel trees in the immediate vicinity of the oak and on how much rain falls over the three weeks prior to the organism arriving at the oak.
The upshot for communities where sudden oak death is a threat, including Woodside, Portola Valley and Atherton, is a straightforward set of recommended steps: