Help Protect California’s & Save Homeowners and City Taxpayers Enormous Expense

Action: contact California Secretary of Agriculture Karen Ross ([email protected]) and the President of the State Board of Food & Agriculture Craig McNamara ([email protected] ) to ask that the California Department of Food and Agriculture (CDFA) regulate the movement of firewood. Also inform your members of the state legislature and Senate and your town’s mayor of your request and ask that they support it.

Rationale:

California’s oak trees are symbols of the state; they improve our neighborhoods, are important components of healthy urban and wildland ecosystems, and support a wide range of wildlife.

These are now threatened by non-native insects and diseases such as the goldspotted oak borer (GSOB), polyphagous shot hole borer (PSHB), and sudden oak death (SOD). Depending upon the of oak and its location, it might be threatened by some or all of these introduced pests.

Oak Species SOD GSOB PSHB California black oak () X X Canyon () X X X Coast live oak () X X X Engelmann Oak () X Shreve's oak ( var. shrevei) X Valley oak () X tanoak (Notholithocarpus densiflorus) X

GOLDSPOTTED OAK BORER

GSOB attacks coast live oak (Quercus agrifolia) – the iconic symbol of California with its wide- spreading branches. Coast live oak grows along the western coastal range, from central California southward to northern . It is particularly well adapted to the fires so common in these ecosystems. Coast live oaks are also found in southern California’s parks, residential landscapes, and streets where they provide shade and aesthetic value.

Since 2002, coast live oak trees in County have been killed by the goldspotted oak borer (GSOB), an invasive species. GSOB outbreaks have now been detected in three additional counties distant from the original outbreak: near the town of Idyllwild in Riverside County; at Weir Canyon just east of in Orange County; and at the town of Green Valley north of Los Angeles in Los Angeles County. GSOB is being spread by human activities!

GSOB also attacks California black oak (Quercus kelloggii), the state’s largest oak. It grows from Baja, California to southwestern Oregon in all mountain ranges of these regions at elevations up to 7,500 feet.

GSOB has killed nearly 100,000 California black oak trees in San Diego and Riverside counties. Black oaks in Yosemite National Park are at risk should GSOB be carried there in campers’ firewood.

Finally, GSOB attacks Canyon live oak (Quercus chrysolepis), an evergreen that grows at lower elevations of the mountains of southern Oregon and California, eastward to and New Mexico. It is a common element in the mixed evergreen forests of California and is somewhat resistant to sporadic fires.

POLYPHAGOUS SHOT HOLE BORER

A second threat to oaks comes from the polyphagous shot hole borer (PSHB -Euwallacea sp.) and the Fusarium fungus which it carries. This disease complex threatens coast live oaks and possibly canyon live oaks. This disease complex is found in parts of Los Angeles, Orange, San Bernardino, and Riverside counties. An apparently related disease is in San Diego County. The insect attacks more than 300 types of woody , among them 11 species native to southern California; 13 agriculturally important trees, such as avocado; and 53 species that, cumulatively, constitute more than half of all trees planted in urban areas of southern California.

GSOB is thought able to spread throughout much of the state. ALL Areas at Risk to GSOB of the GSOB outbreaks are believed to have resulted from movement of wood infested by GSOB – most likely firewood.

Continuing to allow people to move firewood helps the insect spread to new, vulnerable areas. Such vulnerable areas include Yosemite National Park. In order to slow their spread, people need to be persuaded to stop moving firewood – whether it is for a weekend camping trip or to supply stoves in their homes or vacation retreats.

Many entities in California participate in educating people about the pest risk associated with firewood, including CalFire (the forestry department) and CDFA. However, the absence of regulations restricting movement of firewood undermines the message. First, the lack of regulation allows firewood vendors to ignore the educational message, since there is no sanction. At a deeper level, failure to regulate also conveys an impression that the risk associated with firewood is not considered sufficiently serious to warrant an official response. Failure to regulate firewood movement means that GSOB and PSHB will spread more quickly from southern California to cities, suburbs, and wildland areas in the central and northern parts of the state. The result will be loss of the oaks’ ecosystem services and huge costs to homeowners and municipalities because they will be forced to remove dead and dying trees before they fall.

(The polyphagous shot hole borer originated in Vietnam, a tropical country. Therefore, it might not spread into northern parts of California – although no one yet knows its limits.)

For more information on sudden oak death, visit http://www.suddenoakdeath.org. For more information on the goldspotted oak borer, visit http://www.gsob.org. For more information on the polyphagous shot hole borer, visit http://eskalenlab.ucr.edu/avocado.html.

Information provided by Faith Campbell, Center for Invasive Species Prevention; [email protected]