A new pest is threatening trees in Los Angeles County — the Polyphagous Shot Hole Borer (PSHB). The beetle bores through a tree’s bark and spreads a fungus that attacks the wood, disrupting the flow of water and nutrients the tree needs to survive. Eventually, branch dieback and death of the tree can occur. With the ability to attack a wide range of trees, this pest has already killed a large number of avocados internationally, box elders, oaks and other species along streets and in botanical gardens and backyards in Los Angeles County.

Like the Gold Spotted Oak Borer (GSOB), which has killed oaks in San Diego County and was recently found in Riverside County, the PSHB beetle may cause serious impacts in urban, suburban and wildland areas of Southern California.

In response, UC Cooperative Extension will co-host a hands-on workshop with the Resource Conservation District of Santa Monica Mountains and the Huntington Library, Art Collections, and Botanical Gardens. Homeowners will learn from experts how to identify new oak threats, including PSHB and GSOB, and a variety of common, rare and emerging insects and diseases. It is also an opportunity to meet local tree care and pest management professionals and hear ways to contribute to local monitoring efforts.

New Oak Threats Workshop

Jan. 12, 2013, 8:30 a.m. to 2 p.m.

The Huntington Library, Art Collections, and Botanical Gardens in San Marino

Advance registration is required with a $25 fee.

To register, please visit http://ucanr.edu/sites/socaloakpests/.

“These pests have the potential to seriously impact trees at homes, streets, parks and wildlands. It’s quite frightening,” said Sabrina Drill, natural resources advisor in Los Angeles County. “We need homeowners and tree care workers to be on the lookout to prevent the spread of this thing, particularly through firewood movement,” she added.

To learn more about Southern California’s oak trees, visit http://ucanr.edu/sites/socaloakpests/.

For more information on Cooperative Extension’s natural resources program, visit http://celosangeles.ucdavis.edu/Natural_Resources/.