Oak disease's latest victims - Clippings

University of California researchers recently reported that two more of the state's trees--coast redwood and Douglas-fir--are susceptible to Sudden Oak Death (SOD), a disease caused by the pathogen Phytophthora ramorum.

This summer scientists were testing the branches and needles of coast redwood to see if it had been affected (Clippings, Summer 2002). Their fears were confirmed, and the tree was added to a growing list of species threatened by the deadly disease.

In addition to the redwood, Doug-fir saplings have shown symptoms of infection. According to The Forestry Source newspaper, the extent to which the disease will affect these two stalwarts of California's forest industry remains to be seen. State officials have said that both species would he a focus of state and federal regulations aimed at preventing the disease's spread.

When a tree contracts SOD it begins to ooze reddish brown sap, the crown wilts, and the tree suddenly dies. The deadly disease has killed coast live oak, tanoak, and California black oak and killed or sickened additional species ranging from bigleaf maple to evergreen huckleberry.

Last April a federal quarantine banned the shipment of soil and plants from more than a dozen host species outside the infected countries. State regulations prohibit plants, plant parts, unprocessed wood, and wood products from being moved within or from infested counties without the authorization of the local county agricultural commissioner.

California Governor Gray Davis (D) has also requested $10 million in federal aid to help fight SOD's spread. In a letter to President Bush, Davis wrote, "The implications of this disease are enormous, including a major change in the environment and landscape of California, severe economic dislocation, and an increase in fire danger."

When trees die in large numbers, it poses a threat for wildfire, erosion, and stormwater runoff. Wildlife habitat deteriorates, landslides are more likely, and watersheds can become drought-prone.