Bark Beetles Thrive on Drought, Threaten Pines Over Wide Area

Bark beetles the size of pencil tips but extremely opportunistic in times of drought have killed or infested hundreds of acres of pines in the mountains of San Diego County, and forest managers say there is little more to do than hope for rain.

Twenty-one representatives from the U. S. Forest Service, the California Department of Forestry and the state park system met Wednesday at the Escondido Public Library to determine the extent of the worst pine-beetle infestation in 30 years. The infestation is said to be reaching epidemic proportions from the San Jacinto Mountains in San Bernardino County to the Laguna Mountains in San Diego County.

Palomar Mountain has suffered the worst infestation in San Diego County, with an estimated 75 acres of pines already killed, according to Roger Wong, a resource manager with the Palomar District of the U. S. Forest Service.

Officials with the U. S. Forest Service said the number of dead and infested trees is substantially lower on land where infested trees have been removed and forests have been thinned, such as in the Laguna Mountains. The state park system, which governs Cuyamaca Rancho State Park, stands by its policy of “letting nature take its course” and is not removing infested trees or spraying with insecticides.

Eradication Efforts Hurt

Some U. S. forest officials have said that their efforts to eradicate the bugs--ips and Western pine beetles--may be hampered by movement of beetles from state parkland.

“The drought, combined with a lack of logging and thinning, has caused this problem,” Wong said in an interview Monday. “The Forest Service wants to control the beetle outbreak. We don’t feel this is a very healthy situation for the forest, both in terms of retaining the pines and because it presents a fire management problem. We want to retain our coulter- and ponderosa-pine tree cover, even if it is a natural outbreak.”

Jack Shu, district superintendent for Cuyamaca and Palomar state parks, said, “The state parks’ position has been that infestations of natural cause should be let go. We’ll have to look at it further to see if we have to take any action.”

After nearly four hours of discussion, an entomologist with the U. S. Forest Service summed up what can be expected as Southern California enters its third drought year.

Heavy Rain Needed

“The crystal ball is this: If the forests are unhealthy, as they are right now with the drought, the beetles will be in abundance. This cold weather we’re having is not going to affect them at all. (The only hope) is for us to return to normal or above-normal rainfall to relieve the drought stress,” entomologist Bruce Roettgering said.

The ips and Western pine beetle are indigenous to Southern California’s forests, but two years of drought have weakened many trees, resulting in an explosion in the beetle population. A healthy tree has sufficient moisture to build up adequate pressure behind its sap to “pitch” the beetles out as they burrow through the bark.

No formal policy decisions were made at the meeting, but most representatives agreed that forest managers at best will only be able to save the pines in small target areas, such as campgrounds and government land adjacent to valuable private holdings.

Officials said private landowners in the Julian and Palomar Mountain areas can hire professional pesticide sprayers to coat their trees with a protectant called carbaryl, which is about 90% effective in repelling the beetles.