Health Appraisals for your San Diego Oak Trees

Attention favored clients owning Oak trees in San Diego, please read the following: Insect pest destroying Oaks!

Note: DO NOT use any out of area or infected Oak for firewood! Below is a picture of the culprit. Hopefully you'll never see it or its devastating effects.

The potentially lethal gold-spotted Oak borer is threatening California's treasured Oak trees. The virulent super beetle attacks trunks and branches of healthy, adolescent and mature Oaks. It feeds primarily on the bark. of the tree (Photo courtesty U.S. Forest Service).

To protect Southern California's majestic oaks from this emerging threat, officials are urging San Diego County residents NOT to bring in firewood from outside the county, and to avoid cutting down back country Oaks to use for firewood. It's suspected this killer bug came into the area from tainted/imported firewood, possibly from Mexico.

The brown, bullet-shaped beetle with gold spots on its wings is attacking Coast Live Oaks (Quercas agrifolia), California Black Oaks and Canyon Live Oaks in the mountains of eastern San Diego County, south of Julian. This bug is endemic to Mexico and Guatemala and has been found in recent years in the Southwest states of Arizona and California.

The gold-spotted oak borer attacks the trunks and branches of healthy, mature oaks, feeding on the bark, and in turn, cutting into the Cambium layer of the tree.

Tom Coleman, an entomologist for the Cleveland National Forest, and the person who discovered the insect problem, and who is studying the pest, said, "I tend to believe it was brought in on firewood, most likely from Mexico."

There are well over half a million acres of Oaks in Southern California. Most of the trees are found within 40-50 miles of the ocean. Some of the largest local stands are in the hills between Ramona and Julian, on Palomar Mountain and on the Santa Rosa Plateau near of Murrieta, among other places. These are also areas that have particularly dry micro climates. The areas off Sunrise Hwy in the Laguna's, have also been decimated as well. Everywhere you look, you'll see dead Oak trees. It's devastating.

At the same time, the Cleveland National Forest's Palomar and Descanso districts have stopped issuing permits to cut oaks for firewood, Coleman said. Everyone needs to be vigilant about firewood use and report any suspicious activity in this regard.

The recent rains this February 2009 have helped bring stress levels down, but it doesn't help that the region's prized oaks already are under stress because of the severe and prolonged drought that has persisted most of this decade. Several years ago S.D. received a total of only four inches of rain. That's about the equivalent of the annual rainfall for the Saraha Desert!

Just as stress affects people and animals, it also impacts trees. The single greatest source of stress for tress is dehydration. That's why it's important to periodically have a Certified Arborist examine and check up on your Oak trees..

Particularly troubling is the fact that this insect is invading even healthy areas. "We're even seeing it in people's yards, where they are getting water," Entomologist Coleman said.

Mr. Coleman estimates that more than 17,000 Oaks have been lost to the borer around Julian, Alpine, Pine Valley, Descanso and Mount Laguna, at elevations ranging from about 2,000 feet above sea level to 6,000 feet.

So far, no eradication effort is under way because little is known about the beetle, Coleman said. However, keeping your trees properly hydrated, particularly during the hot/dry months, and properly fertilized, will help.