A pathogen that has devastated wide swaths of California's oak trees has been discovered on the grounds of UC Berkeley, campus officials announced Oct. 31, 2001. The microbe responsible for sudden oak death (SOD) has infected three host species, including two California bay trees near the Faculty Glade. The infection has not been detected in any of the oak trees on campus, suggesting that it arrived recently.

Matteo Garbelotto of the UC Berkeley College of Natural Resources noticed the infections while walking through campus. Subsequent tests confirmed that the infections were caused by Phytophthora ramorum (see California Agriculture, January-February 2001). Garbelotto and UC Davis associate professor Dave Rizzo, in conjunction with the California Oak Mortality Task Force, were recently awarded a $1 million grant from the San Francisco-based Gordon and Betty Moore Foundation, to study P. ramorum.

Approximately 50 campus groundskeepers, gardeners, arborists and horticulturists from UC Berkeley's Botanical Garden have received training to identify signs of SOD infection. They are canvassing the campus and gathering samples of suspicious vegetation. Disease management will include regular monitoring of the campus grounds and preventative treatments with fungicides. Areas surrounding the campus also will be surveyed through a joint effort between UC Berkeley and the Alameda County Agricultural Commission.

There are at least 10 known tree and plant species that are susceptible to the P. ramorum pathogen. 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.

Nonnative Argentine ant workers nurture scale insects in exchange for the sweet honeydew they excrete. By protecting scale, aphids and other homoptera from potential predators, Argentine ants promote populations increases among these agricultural pests.

SOD 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 recently been discovered along Crow Canyon Road in Alameda County and near Lake Madigan in Solano County.