Peninsula tanoak trees will serve as guinea pigs in a new federal experiment that will study their resistance to Sudden Oak Death syndrome — caused by a fungus thathas killed tens of thousands of trees since its discovery in 1995.
The Midpeninsula Regional Open Space District is backing the USDA Forest Service’s study with $60,000 in funding over the next three years, and has already contributed tanoak acorns from the district’s 17 preserves in San Mateo and Santa Cruz counties.
Those acorns — along with ones from Marin, El Dorado and Monterey counties and from Oregon — will be inoculated with the phytophthora ramorum fungus and then returned to disease-infested areas to see which ones resist infection as they grow, according to Susan Frankel, program manager with the forest service.
"We wanted to be involved, because Sudden Oak Death is so bad here," said Cindy Roessler, resource management specialist with the open space district. The district has not counted its dead trees, but thousands have died since the fungus arrived on the Peninsula in the late 1990s.
While tanoaks are the most susceptible, some also possess a natural resistance to Sudden Oak Death.
"The long-term goal is to figure out a way to use [its] natural resistance to our advantage," Frankel said. "But how we get to that point to manipulate the resistance, it’s a long way and we’re just starting."
The phytophthora fungus responsible for Sudden Oak Death spreads through ecosystems during rainy spring weather and weakens trees when they’re stressed, killing them within three to five weeks. It kills several kinds of oaks — including coast live, black and canyon oaks, along with ornamental plants like rhododendrons — and infects other flora, from California bay laurels to redwoods.
Discovered in 1995, Sudden Oak Death has been identified in 14 Bay Area and coastal California counties, along with Curry County in Oregon, according to Roessler. It now garners $4 million in annual federal funding.
The forest service’s tanoak experiment is just the latest in a battery of research projects undertaken by the federal government and the University of California, according to Dave Rizzo, associate professor of plant biology at the University of California at Davis. Even so, scientists’ understanding is only just beginning.
"We’re still trying to learn its life cycle," Rizzo said. "We can protect individual trees with fungicides, but what do we do with infected forests? We need to learn about the ecology of these forests."