Get Familiar with the Invasive Pests Threatening California Oaks
Beatriz Nobua-Behrmann, University of California Cooperative Extension, Orange and Los Angeles Counties
Julie Clark de Blasio, University of California Cooperative Extension, Ventura County
Randall Oliver, University of California Integrated Pest Management Statewide Program
More than 21,000 oaks have died in urban and natural areas of California during the last ten years as a consequence of invasive tree pests’ attacks. This extended tree mortality causes significant economic, ecological, cultural, and aesthetic losses to the region. Among the most relevant invasive insect pests currently threatening California trees are the goldspotted oak borer (GSOB), the invasive shothole borers (ISHB), and the Mediterranean oak borer (MOB). GSOB and ISHB have been present in Southern California since the early 2000’s, and they continue to spread throughout the region. MOB has been recently discovered in Napa County and surrounding counties, but the full extent of its distribution is still undetermined.
All three of these pests can survive in down wood for long periods of time, and often are invertedly spread to new locations through the movement of infested firewood and green waste. Actions to prevent the spread of these pests include buying firewood locally where it will be used ensuring the correct disposal of green waste (which includes chipping infested wood and, in some cases, solarizing or composting the chips).
As with any invasive species, finding infestations in the early stages allows for proper containment, management and, in some lucky cases, eradication. The key to make this early detection possible is to educate all stakeholders, including arborists, pest control advisers, government agencies, campground managers, and the general public, on how to identify and report the presence of these pests.
The University of California Cooperative Extension will be presenting and staffing a booth at the 8th California Oak Symposium with information about these three pests, including how to identify their presence, prevent the spread, and manage current infestations. More information on these pests can also be found at their respective webpages (www.ISHB.org, www.GSOB.org, and www.MOBpc.org), which include current information regarding distribution, identification, host species, and management, as well as tools to report suspected new infestations.