Cal Neighbors

A newsletter for neighbors of the University of California, Berkeley

Winter 2002
A special report on the role of the campus in the regional economy
UC Berkeley's impact goes beyond dollars and cents, report shows
Public use of campus library

Researchers work to halt oak disease
Researchers work to halt oak disease

By Sarah Yang

Oakland, Live Oak Park, Thousand Oaks neighborhood . . . If any plant or tree is identified with the East Bay, it is the gnarled and beautiful native oak.

Now, UC Berkeley researchers are working to contain the spread of a pathogen that has devastated wide swaths of California's coastal oak trees and has been discovered in Alameda County, including the Berkeley campus.

Sudden Oak Death was first noticed in Marin County in 1995 and has since felled tens of thousands of coast live oaks, black oaks and tan oaks in the state. Infections have also been discovered along Crow Canyon Road in Alameda County and near Lake Madigan in Solano County.

There are at least 10 known tree and plant species that are susceptible to the Phytophthora ramorum - the invasive microbe responsible for Sudden Oak Death. The highly contagious microbe is a brown algae related to the species responsible for Ireland's potato famine of the mid-1800s. Its ability to infect a wide array of plant
life through soil, water and air has made it particularly difficult to control.Identifying the microbe is not easy or clear cut. There are limited distinctive, diagnostic symptoms on many of the hosts, so confirmation in a laboratory is required. Even experienced researchers can't always tell whether or not a declining tree is infected.

Matteo Garbelotto, a leading researcher in Sudden Oak Death and a forest pathologist at UC Berkeley's College of Natural Resources, first noticed the infections in Berkeley while walking through campus. Subsequent tests confirmed the infections were caused by Phytophthora ramorum. The microbe has been found on at least three host species on the campus, including buckeyes and bay trees near
Faculty Glade and in an undeveloped area of the UC Botanical Garden.

"Within this genus, there is nothing else that can spread the way this pathogen can," said Garbelotto, who is also adjunct professor in the Department of Environmental Science, Policy & Management. "We're only beginning to understand how it spreads, and how it might be stopped." Campus groundskeepers, gardeners, arborists and horticulturists are now canvassing the campus and the botanical garden to determine how widespread the disease is.

Garbelotto has tested chemical treatments on hundreds of potted oak trees infected with P. ramorum. He found that phosphites injected through small drilled holes in the tree slowed the growth four-fold and significantly reduced the appearance of lesions.

He also found that coating the trunk of the tree with copper sulfate could prevent the microbe from entering the oak. The preventive treatment has already been used for the oak trees near the known points of infection on campus.

For concerned residents, the best defense against Sudden Oak Death is to promote general tree health: avoid frequent irrigation of oak trees, do not damage tree roots by paving and soil compacting, prune dead and dying branches in the dry summer months, and fertilize if the leaves are yellowing.

For information on Sudden Oak Death, visit http://www.suddenoakdeath.org/ or http://cemarin.ucdavis.edu/index2.html