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Since oak mortality in east San Diego County was attributed to Goldspotted Oak Borer (GSOB) in 2008, infestations have spread throughout the county and beyond. Satellite GSOB infestations were identified in Riverside County in 2012, Orange County in 2014, and Los Angeles County in 2015.
The adult goldspotted oak borer (GSOB) Agrilus auroguttatus is a small, bullet-shaped beetle about 10mm (0.4 in.) long and has six golden yellow spots on its dark green forewings. Mature larvae are white, legless, slender and about 18mm (0.75 in.
If wood cant be moved away from uninfested trees, consider covering the wood piles with thick mil, clear, plastic tarp or metal window screen (with a mesh small enough to stop mosquitoes) to trap emerging GSOB until they die from starvation.
Removing the bark and drying small pieces of oak firewood under direct sunlight for one growing season is another tactic that may help contain pest populations. Homeowners should contact a licensed professional tree care specialist about this treatment option.
The goldspotted oak borer (GSOB) has been found in three species of oak in our area: Coast Live Oak (Quercus agrifolia), Canyon Live Oak (Quercus chrysolepis), and California Black Oak (Quercus kelloggii).
Goldspotted oak borer (GSOB) larvae remain in cut oak logs and firewood from GSOB-killed trees or green infested trees and are a continual threat of further infestation. Wood from GSOB infested trees should not be removed from local infested areas.
Researchers are testing several management tactics for goldspotted oak borer (GSOB) in Southern California. The following management options are provided based on current GSOB research findings.
The damage that GSOB causes has the potential to devastate oak woodlands, as infestations impact the oldest and most prolifically reproducing trees. Poor oak recruitment and regeneration not only threatens the oak forests themselves, but also the wildlife that utilize oak resources.
