Tree & Forest Health

Tree and forest health are affected by many issues, including drought, tree pests, wildfire, etc. This page provides information on the specific concerns in our area, as well as suggestions on what you can do to make a difference.

Gold Spotted Oak Borer (GSOB)

Shot Hole Borers

Don’t move firewood

Tree mortality crisis

Gold Spotted Oak Borer (GSOB): GSOB is an invasive pest that is contributing to the death of thousands of oak trees across San Diego County. Follow the link below to find out more information, including how to identify and report GSOB.

Overview: A New Threat to Oaks in Southern California

Developing an Integrated Pest Management Program


Brochure: A New Threat to Oaks in Southern California

Best Management Practices (BMPs)


Shot Hole Borers: The Polyphagous SHB and Kuroshio SHB attack many types of trees, including native, ornamental, and fruit trees (such as avocado), destroying both natural environments and commercial groves. They spread a disease called Fusarium Dieback, which can lead to tree mortality. The Polyphagous SHB and Kuroshio SHB are different insects, and currently only KSHB is known to occur in San Diego County. However, the two insects and the damage they do are very similar.

Click here for an overview on the two beetles, including links to a wide variety of resources:

Click here for list of known host species, which will help you better understand the risk to trees on your property:

A Devastating Threat to California Trees

Prioritizing Management Efforts

Identifying Symptoms and Look-Alike Pests



Don’t move firewood: Destructive insects and diseases often lurk in firewood. Moving firewood can help transport pests that destroy trees and forests – sometimes even hundreds of miles away. Remember to burn it where you buy it!

For California standards


Tree mortality crisis: Due to the deadly combination of drought and bark beetles, California is experiencing a tree mortality crisis. Weakened by four consecutive years of drought, over 66 million conifers and hardwood trees have succumbed to bark beetle attacks, and died. This is a serious issue – especially as it pertains to wildfire – that needs all of our support.