- Author: Mary Louise Flint
First identified in California in 2004, the goldspotted oak borer (GSOB), Agrilus auroguttatus, has killed more than 24,000 oak trees in San Diego County since its arrival, probably in the late 1990s. In 2012, it was detected in Riverside County and it is expected to spread northward in the state.
The most seriously damaged oaks are those in the red oak group including coast live oak, Quercus agrifolia, and black oak, Q. kelloggi. It also infests canyon live oak, Q. chrysolepis but has not been found to kill the other native oak species in the area, the Englemann oak, Q. englemanni. So far losses have been most serious in parks and forested areas, but landscape trees are also being killed.
A new Pest Note from the UC IPM program outlines management guidelines for this serious pest. Flatheaded borers such as GSOB are difficult to manage and seriously infested trees cannot be saved. The primary way GSOB spreads into new areas is through the movement of infested wood and the authors recommend leaving infested wood on site for 2 years. If wood is to be moved, the Pest Note provides guidelines for treating it through containment, grinding, and debarking. Guidelines for replanting infested areas, less susceptible oak species, biological control, insecticide applications and developing GSOB management plans are also described.
Many other borers attack oaks but do not kill trees. GSOB infested trees can be distinguished by the characteristic D-shaped emergence holes it leaves behind. A special feature of the Pest Note is a table illustrating the emergence holes of borer species on southern California oaks. Many photos are also included.
The information in this Pest Note: Goldspotted Oak Borer is based primarily on research studies by the authors: Mary Louise Flint (UCIPM and Entomology/UC Davis), Tom Coleman and Steve Seybold (USDA/US Forest Service), and Mike Jones (Entomology/UC Davis). Find it at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74163.html
- Author: Mary Louise Flint
Memorial Day weekend, traditionally considered the beginning of California's camping season, is right around the corner. If you are preparing for an upcoming trip, keep in mind that you can help protect California's forests by buying firewood from a local source near the campsite rather than bringing it with you.
When people move wood from place to place, they may also be moving invasive insects and diseases that threaten California's landscape and wildland trees. The goldspotted oak borer, which is devastating native oaks in San Diego, was likely brought there from Arizona in firewood. The polyphagous shothole borer, walnut twig beetle and thousand cankers disease, and the pathogen causing sudden oak disease, all continue to spread to new areas on infested wood chips, plant debris, or wood moved for woodworking or firewood.
Over the past year, the California Firewood Task Force has asked the public to "buy it where you burn it"—that is, don't bring wood from home when you camp, do use wood from local sources, and leave leftover wood at the campsite for the next camper. Even if wood does not appear to have borer holes or other evidence of pests, don't assume that the wood is pest free. Be on the safe side and don't move it.
The California Forest Pest Council established the Task Force in 2011 to educate Californians about what they can do to prevent movement of invasive pests in wood. The Task Force developed a Web site, put up billboards across California, sponsored children's activities at parks and fairs, encouraged campgrounds to sell only local firewood, gave presentations across the state, and developed best management practices, posters, and other information to engage the public.
For more information visit www.firewood.ca.gov/.
- Author: jggonzales@ucanr.edu(Jan Gonzales)
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