Invasive Spotlight: Goldspotted Oak Borer (GSOB)

GSOB

Adult goldspotted oak borer, Agrilus auroguttatus, on an oak leaf. Photo by Mike Lewis, Center for Invasive Species Research, Bugwood.org

There are several flatheaded boring beetles in California, however only a few are of particular concern. The goldspotted oak borer (GSOB), Agrilus auroguttatus, is a metallic wood-boring beetle that threatens our native trees. Since it was introduced to Southern California on contaminated firewood in the early 2000s, this pest has caused extensive damage to woodlands and native oaks.

What does the goldspotted oak borer look like?

Adult GSOB are 0.4 inch long and 0.08 inch wide with bullet-shaped bodies. They are black with an iridescent green sheen and six distinct gold spots on their back.

What damage does the goldspotted oak borer cause?

Goldspotted oak borers only attack oaks (Quercus spp.). They are particularly damaging to coast live oak and California black oak. Adult beetles lay eggs on host trees and the larvae bore into the wood, feeding on the tree's vascular tissue. The larvae feed on the tree until they pupate into adults and exit the tree, leaving D-shaped exit holes in the bark. Extensive GSOB feeding can girdle trees, disrupting water and nutrient uptake and eventually causing the tree to die. 

What can you do about the goldspotted oak borer?

Don't move firewood! The most important way to prevent the spread of invasive wood borers like GSOB, is to buy firewood where you're going to burn it. If you live in an area of Southern California where GSOB is present, avoid planting susceptible trees. If you need to remove an infested tree, keep the cut wood away from healthy oaks and tarp or grind the wood to kill any larvae present. To report possible sightings, fill out the Goldspotted Oak Borer Symptoms Reporting Form at https://ucanr.edu/sites/gsobinfo/What_You_Can_Do/Report_GSOB_Symptoms/

To learn more about this invasive pest visit the UC IPM Pest Notes: Goldspotted Oak Borer or the UC ANR Goldspotted Oak Borer page.

Invasive Spotlight: Highway Iceplant

A patch of highway iceplant, Carpobrotus edulis. Photo by Mitch Barrie, Flickr.com.

You've probably seen this invasive plant growing along highways or the coast in California. Highway iceplant, Carpobrotus edulis, was intentionally introduced to prevent soil erosion along highways and coasts but it has since invaded many different ecosystems and outcompetes native plant species. The California Invasive Plant Council (Cal-IPC) rated this plant as an A-1 species, meaning it is one of the “most invasive and damaging species that are widespread in the state.”

What does highway iceplant look like?

The highway iceplant, also known as the hottentot fig, is a succulent with fleshy three-sided stems. It grows as dense ground-covering mats and produces large yellow to light pink flowers in the late spring and early summer.

What can you do about highway iceplant?

For decades iceplant was widely promoted as an ornamental landscape plant. While its popularity has dwindled, it may still be available for sale in some nurseries. Avoid buying and planting iceplant. Instead, choose plants native to California and visit the PlantRight website to find similar-looking alternative plants. If you have iceplant on your property, it can easily be removed by hand pulling. Be sure to get all live shoots as it can regrow from any node left behind.

For more information, visit the UC IPM Pest Notes: Invasive Plants or the Cal-IPC Plant Report on the highway iceplant.

The UC Master Gardeners are now accepting applications.  The deadline is quickly approaching!  Please have your application postmarked by November 20th.

Please click on the underlined links below to find the application and more information about our program.

Photo by Cindy Muther