Many forest insects and diseases in California thrived in 2013, in part due to the ongoing statewide drought, according to the just published California Forest Pest Conditions Report for 2013. Extremely dry conditions placed additional stress on forests that were already enduring the effects of overcrowding. Dense groups of trees competing for limited site resources are extremely susceptible to injury and mortality from insects and diseases as well as fire, especially during drought conditions.
In 2013, invasive species such as the goldspotted oak borer, previously only found in San Diego County, spread to Riverside County. Sudden oak death killed an additional 294,000 coastal oak and tanoak trees over approximately 47,500 acres, and the newly identified invasive polyphagous shot hole borer/Fusarium disease complex spread from Los Angeles and Orange Counties into Riverside, San Bernardino, and San Diego Counties. Over 110 plant species were found to be hosts of the complex, with damage and mortality found in such species as coast live oak, avocado, olive, persimmon, and big leaf maple, as well as numerous other popular, common plants.
Each year the California Forest Pest Conditions Report documents information on forest health and pest issues impacting California’s forests, woodlands, and urban trees. It is intended to be a resource for forest managers, pest management specialists, landowners, and other interested parties both within and outside of California.
“Californians should to be concerned with current urban and wildland forest health issues which affect all of us, economically and emotionally,” said Chair of the California Forest Pest Council Bob Rynearson. “The Forest Pest Conditions Report is a simple way for policy makers, land managers, and homeowners to keep abreast of the latest trends in our state.”
The California Forest Pest Conditions Report is a publication of the California Forest Pest Council and its associated members. Contributors include the USDA Forest Service, Pacific Southwest Region, Forest Health Protection; California Department of Forestry and Fire Protection; the California Department of Food and Agriculture; University of California (UC); and UC Cooperative Extension.