Oak borer infestation not an epidemic on the Hill: Much more damage cited in San Diego County

Share via email

The Goldspotted oak borer has established itself in Idyllwild, but its spread and breadth have been much slower than its invasion in San Diego County, according to Dr. Tom Scott and Kevin Turner, both of the University of California, Riverside, Cooperative Extension.

Both men were in Idyllwild last week to discuss the GSOB presence and current conditions with members of the Mountain Community Fire Safe Council and its GSOB volunteers.

“We’re still discovering trees [with GSOB], but we’re not seeing an escalating outbreak,” Scott said. “We’re still finding trees already infested, but they are not spreading rapidly.”

As of early October, a total of 53 trees on the Hill had been identified as being the target of GSOB infestations. Since the first identified tree was in the fall of 2012, both men thought the GSOB’s infestation has been slower and less pervasive than in San Diego County.

There, the GSOB’s presence has begun to spread throughout the county from its original locations. Scott described what he believes is the first natural expansion of its habitat since it has been found in a location miles from human habitat. Since the beetle’s larvae are within the bark of oaks, officials have thought the beetle spreads primarily through the transport of oak firewood until this discovery.

While it is still early to identify the difference between the GSOB’s spread here and in San Diego County, Turner acknowledged that no other community has committed as much resources — funding and volunteers — to combat the insect’s invasion of forest oaks as Idyllwild.

Scott estimated that nearly 40,000 acres in San Diego have been identified as GSOB locations. Between 50,000 and 200,000 oaks have probably died as a result of this infestation, he added.

Exacerbating the insect’s damage, and a possible harbinger of more damage, is its attack on Coastal Live oaks near Mt. Palomar. Previous GSOB victims have been limited to Black oaks.

The Goldspotted oak borer has established itself in Idyllwild, but its spread and breadth have been much slower than its invasion in San Diego County, according to Dr. Tom Scott and Kevin Turner, both of the University of California, Riverside, Cooperative Extension.

Both men were in Idyllwild last week to discuss the GSOB presence and current conditions with members of the Mountain Community Fire Safe Council and its GSOB volunteers.

“We’re still discovering trees [with GSOB], but we’re not seeing an escalating outbreak,” Scott said. “We’re still finding trees already infested, but they are not spreading rapidly.”

As of early October, a total of 53 trees on the Hill had been identified as being the target of GSOB infestations. Since the first identified tree was in the fall of 2012, both men thought the GSOB’s infestation has been slower and less pervasive than in San Diego County.

There, the GSOB’s presence has begun to spread throughout the county from its original locations. Scott described what he believes is the first natural expansion of its habitat since it has been found in a location miles from human habitat. Since the beetle’s larvae are within the bark of oaks, officials have thought the beetle spreads primarily through the transport of oak firewood until this discovery.

While it is still early to identify the difference between the GSOB’s spread here and in San Diego County, Turner acknowledged that no other community has committed as much resources — funding and volunteers — to combat the insect’s invasion of forest oaks as Idyllwild.

Scott estimated that nearly 40,000 acres in San Diego have been identified as GSOB locations. Between 50,000 and 200,000 oaks have probably died as a result of this infestation, he added.

Exacerbating the insect’s damage, and a possible harbinger of more damage, is its attack on Coastal Live oaks near Mt. Palomar. Previous GSOB victims have been limited to Black oaks.

Share via email

Leave a Reply

Your email address will not be published.

s2Member®