Invasive Oak Borers

Oak and Shot Hole Borers are coming to eat our trees!

University of California Cooperative Extension, Cal Fire and others sponsored a workshop on Goldspotted Oak Borers and Invasive Shot Hole Borers May 9. These are two different beetles but they both affect our forests.  GSBs came to California on firewood and are being transported from Southern California around the state that way. They affect our Coast Live Oaks, infesting large, mature, healthy trees. They have not yet arrived in SLO County, but they are moving up from the south.

The key to preventing them from spreading is educating the public not to transport firewood. The bugs travel in the bark. Oak firewood is valuable, so after trees are taken down, the uninformed and the unscrupulous may haul firewood around. Website.

Invasive Shot Hole Borers don’t eat the wood, but they infect the trees with a fungus that then kills the tree. Box Elders are especially vulnerable and may become amplifier trees that host millions of beetles and then infest all the trees around them.

Disneyland had a severe problem and sent some of their Tree Assessment Team to the workshop. The best strategy to manage them is to monitor and identify infested trees early on and spot treat them.

Forming an Emerging Forest Pest Committee could help. Cal Fire’s Kim Corella offered to connect with the Forest Committee, Greenspace and the Cambria CSD to create a network in the event an infestation is found. One beetle was found in a trap in SLO County, so the assumption is that this is a When, not an If.

These entities, UC, Cal Fire, can help, but eradicating these pests is on us. Local and private organizations can act faster than government. SLO’s city arborist said that as the city has grown, his budget and staff have been cut. He can only react to the most urgent situations, trees down and the like.

Orange County has already lost all its Box Elders. Visual surveys are the best way to identify infested trees. Individuals looking at trees are most likely to be the first ones to spot these pests. Check, and for detailed information on what to look for and how to ask for help to confirm whether the damage is from these insects.

shot hole borer

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