By Julie Clark, Community Education Specialist III
Goldspotted borer (GSOB) is a beetle invasive to oaks in California. Infestations have ravaged oak woodlands in San Diego and Riverside counties the last 12 years and in Anaheim Hills, Angeles and San Bernardino National Forests the last few years. Preferred hosts are black oak, canyon oak, coast live oak, and occasionally Engelmann oak.
Oak woodlands are highly valued ecosystems that support numerous species of fauna. Oak trees serve as the anchor for these systems and support over 5000 insect species, over 105 bird species, 105 mammal species, 58 species of amphibians and reptiles during their respective life cycles. Many beneficial insects rely on oaks to complete their life cycles and do not damage the trees in doing so.
The insects damage the water and food transfer structures (xylem and phloem) of the tree, causing crown die-back and eventual death in heavily infested (amplifier) trees. Widespread loss of oaks from GSOB has occurred in Idyllwild and San Diego County mountain areas.
Although GSOB are winged, they do not fly long distance. UC researchers, partners with CAL FIRE and the California Firewood Task Force discovered that several of the infestations throughout Southern California were caused by introduction of firewood imported from infestations in other areas.
D-shaped GSOB exit holes. Credit: UC ANR
Ventura County is vulnerable to attack by the beetle and other invasive tree pests that are on watchlists for the area. Best ways of being assured your firewood is safe include purchasing locally source material or selecting kiln-dried or certified firewood.
For more information:
Report suspected GSOB infestation:
- Author: Mary Louise Flint
[From the April 2014 issue of the UC IPM Green Bulletin newsletter]
Over the last several decades dozens of exotic pests have invaded California landscapes, causing at least temporary havoc and sometimes severely affecting the aesthetic value of plants or even killing them. Giant whitefly, hackberry woolly aphid, eucalyptus red gum lerp psyllid, Diaprepes root weevil, myoporum thrips, light brown apple moth, spotted wing Drosophila, and olive fruit fly are just a few now established pests that were unknown in the state 25 years ago.
These invaders have come from all over the globe—Asia, Africa, Europe, Australia, Central and South America, and parts of North America. Many new pests arrived on nursery stock; others were imported with shipments of wood, produce, or packing material. Some pests were inadvertently brought in on vehicles or with travelers. Many safeguards including quarantine programs, border inspections, careful procedures at plant nurseries, and outreach programs to educate the public about not moving wood, plants, or produce into the state have had a significant effect in reducing the spread of invasive pests. However, despite these efforts, there is little doubt that new species will continue to arrive.
Five of the newest invaders of concern to landscapers are described in the following paragraphs. For information on these and other exotic pests see the web sites of the UC Riverside Center for Invasive Species Research, the California Department of Food and Agriculture, or the UC Statewide IPM Program.
Goldspotted oak borer. First identified in eastern San Diego County in
Polyphagous shot hole borer. Like the walnut twig beetle, this tiny
Brown Marmorated Stink Bug. A native of Asia, the brown marmorated
This article was originally published in the April 2014 issue of the UC IPM Green Bulletin. See this and other articles at http://www.ipm.ucdavis.edu/greenbulletin/index.html.