As of today, management programs for GSOB are focused on limiting its spread into new areas and protecting healthy oak trees.
WHAT YOU CAN DO
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- MANAGING OAK FIREWOOD PROPERLY: GSOB larvae remain in cut oak logs and firewood from GSOB-killed trees and are a threat of further infestation. Wood from attacked trees should not be removed from local infested areas. Transporting infested firewood is likely the most significant pathway for introducing GSOB into non-infested areas. Never remove or transport oak firewood in or out of parks and campgrounds, burn your supply of firewood before leaving a recreation area, and use only local sources of firewood.
- PLANTING LESS SUSCEPTIBLE OR RESISTANT OAK: when planting trees in infested areas, consider planting native non oak species or Engelmann oak. Diversifying an area with several tree species will provide a more resilient landscape over the long term.
- REMOVING INFESTED TREES: infested trees likely can't be saved and as they die the potential for falling limbs presents a hazard to humans and to structures. In addition, fuel from dead oaks also presents a fire hazard especially around structures. When removing trees, treat and handle cut wood carefully to prevent GSOB spreading (see below for treating cut wood instructions).
- TREATING CUT WOOD: if cut wood must be moved outside the infested area, it should be treated by tarping or screening (containment) for 2 years, grinding, or debarking prior to transport. 1) containment = tarping with clear plastic will contain any emerging adults and prevent them from infesting new trees. Alternatively, small woodpiles can be surrounded with screening to prevent the dispersal of adult GSOB. Leave piles of tarped or screened cut wood on site and in full direct sunlight for at least two years, checking them periodically in order to make sure any hole is secured. 2) grinding = this is the best method to ensure beetles won't survive. Shreding wood into narrow strips will destroy bark and eliminate all life stages of the GSOB. 3) debarking = removing the bark from cut wood will separate the beetle populations from wood. The removed bark need to be destroyed, tarped, or left at the wood collection area, as far away from living trees as possible.
- BIOLOGICAL CONTROL: there are three natural enemies of the GSOB, two parasitoid wasps that attack and kill GSOB larvae and a predatory mite that feeds on larvae, pupae and adults, but none is currently believed to be effective in controlling the beetles from spreading. Woodpeckers also prey on GSOB larvae and pupae in San Diego County, but they are not enough strong to prevent the GSOB from establishing.
- CHEMICAL CONTROL: in general, insecticides treatments for controlling wood borers are more effective for preventing infestation of healthy trees than stopping existing infestations. Severely infested trees should be removed rather than sprayed and wood from these trees properly managed to prevent GSOB spread. If opting for this solution, property owners should hire a pest control professional who has the experience and proper equipment for treating large oak trees.
- HEAT TREATMENT: of instead wood material at 160F for a minimum of 75 minutes in an automated wood-drying kiln has been shown to eliminate many insects and diseases from firewood. However, there is still no evidence which confirms that this temperature and time will kill GSOB.
For more information on management practices and details for the different management options please refer to:
- California Oak Mortality Task Force, (2010). Save trees, keep firewood local. Retrieved from: www.dontmovefirewood.org
- Coleman, T.W., Grulke, N.E., Daly, M., Godinez Cesar, Shilling, S.L., Riggan, P.J., Seybold, S.J., (2011). Coast live oak, Quercus agrifolia, susceptibility and response to goldspotted oak borer, Agrilus auroguttatus, injury in southern California. Forest Ecology and Management, 261, 1852-1865.
- Corella, K.S., Owen, D.R., (2015). Managing Bark Beetles in Urban and Rural Trees. Tree Notes, Nr. 19
- Hagen, B.W. (1990). Keeping native California oaks healthy. Tree Notes nr. 7. California Department of Forestry and Fire Protection.
- Hishinuma, S., Coleman, T.W., Flint, M.L., Seybold, S.J. (2011). Goldspotted oak borer field identification guide. University of California Agriculture and Natural Resources. Retrieved from: http://www.ipm.ucdavis.edu/PDF/MISC/GSOB field-identification-guide.pdf
- United States Department of Agriculture Forest Service (2008). Pest alert. Pacific Southwest Region State and Private Forestry.
You can also contact the Cleveland National Forest's Descanso Ranger District at (619) 445-6235.
- California Oak Mortality Task Force, (2010). Save trees, keep firewood local. Retrieved from: www.dontmovefirewood.org
- Coleman, T.W., Grulke, N.E., Daly, M., Godinez Cesar, Shilling, S.L., Riggan, P.J., Seybold, S.J., (2011). Coast live oak, Quercus agrifolia, susceptibility and response to goldspotted oak borer, Agrilus auroguttatus, injury in southern California. Forest Ecology and Management, 261, 1852-1865.
- Corella, K.S., Owen, D.R., (2015). Managing Bark Beetles in Urban and Rural Trees. Tree Notes, Nr. 19
- Hagen, B.W. (1990). Keeping native California oaks healthy. Tree Notes nr. 7. California Department of Forestry and Fire Protection.
- Hishinuma, S., Coleman, T.W., Flint, M.L., Seybold, S.J. (2011). Goldspotted oak borer field identification guide. University of California Agriculture and Natural Resources. Retrieved from: http://www.ipm.ucdavis.edu/PDF/MISC/GSOB field-identification-guide.pdf
- United States Department of Agriculture Forest Service (2008). Pest alert. Pacific Southwest Region State and Private Forestry.
You can also contact the Cleveland National Forest's Descanso Ranger District at (619) 445-6235.