Evaluating rapid response to a goldspotted oak borer diaspora

In 2012, the goldspotted oak borer (Agrilus auroguttatus, GSOB) was discovered in the mountain community of Idyllwild, 56.3 km north of its known area of infestation. This was the third time that a point of outbreak was discovered >32.2 km from the GSOB infestation area, suggesting that human transport of GSOB has substantially expanded the halo of California communities at imminent risk of GSOB-associated oak mortality. Even though this pattern of dispersal puts more communities at risk, the isolated nature of these new points of infestation offer some hope that their damage could be reduced or controlled by a rapid, initial response. Idyllwild suffered a major die-off of conifers in 2003, pre-adapting the community with an organizational structure, a tree removal/disposal infrastructure, and even some funding that was needed for a GSOB rapid response. Federal, state, and local agencies turned these attributes into a GSOB rapid response plan which also included components of detection, management, and education. As of 2014, our ad hoc response group had mapped the extent of oaks in decline in the region around Idyllwild, contacted all landowners and community residents through mailings and public meetings, conducted three training workshops, and surveyed approximately 154 properties. A total of 53 infested oaks have been found at 20 locations in Idyllwild and the adjacent community of Pine Cove, with the majority removed within a month of their discovery. Cross-sections from dead oaks indicate that infestations began in 2009, and that infested oak firewood may have been delivered to multiple locations generating simultaneous outbreaks. Although detections of GSOB-infested oak increased each year, we believe this represents an increased rate of discovery rather than an increased rate of infestation.