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Zone Of Infestation (ZOI) Definition


The California Board of Forestry and Fire Protection originally declared a Zone of Infestation (ZOI) for Goldspotted Oak Borer (GSOB) on September 12, 2012. This was an official and formal action to recognize GSOB as a threat to California’s forest and woodland resources and exhibits leadership in the effort to combat GSOB while providing the public with important information. The ZOI has since been expanded twice, November 2014 and January 2016, to include new areas of infestation and areas with increased risk to host oak trees.


The value of establishing a Zone of Infestation for the goldspotted oak borer is linked to:

  • Fostering collaborative efforts with both current and potential local, state and federal agency partners working on GSOB prevention, containment, control and remediation.
  • Communicating the concern of both the Department and the Board for the GSOB issue and its current and potential impact in California to the public.
  • Showing support from both the Department and the Board for efforts to seek funding, research, education outreach, best management practices for control, management efforts in managing GSOB-infested wood, and other GSOB related activities.
  • Creating a directive that GSOB suppression and control measures be feasibly addressed in Timber Harvesting Plans within the ZOI (applicable only in mixed conifer stands where oaks are being harvested incidentally along with commercial species of conifers and a THP would be required).
  • Establishing an official mapped boundary of the known GSOB infestation which can serve to notify communities within the current infested area and also to alert communities in neighboring non-infested areas of proximity, spread and threat of GSOB.
  • Expressing the concern to the state legislature and governor’s office about the potential impact and harm that GSOB could have statewide.
  • Partnering with local governments in efforts to help stop the spread.
  • Supporting the use of California Conservation Camp crews in control or management projects for GSOB on private and state lands.

Expansion of GSOB Zone Of Infestation

The California Board of Forestry approved the expansion of the GSOB Zone of Infestation (ZOI) in January 2016. This decision expands the ZOI to include increased acres in San Diego County as well as areas of infestation in Riverside, Orange and Los Angeles Counties. The criteria used to determine the area are known GSOB locations, estimated flight range, locations of host species and lines of convenience (roads, property/ownership lines and other geographical features). For more details, see the following documents and map.

Board of Forestry News Release:GSOB ZOI Expanded (January 27, 2016)

GSOB ZOI expansion request proposal

Goldspotted Oak Borer Zones of Infestation - January 2016

gsob_zoi_map_01_27_16_crpd (3x4in_300dpi)

Print Map (Large PDF file)