Los Angeles

Southern California Trees Infested With Destructive Beetles

The beetles weaken trees' limbs and cause them to fall off by transporting fungi, which colonize and block nutrients from reaching the tree's branches.

Hundreds of Southern California trees are infested with a destructive beetle causing their branches to become weak and fall off.

About 65 infected trees were removed from Central Park in Huntington Beach last week, after the polyphagous hold borer, a type of Ambrosia beetle, took up residence in the trees. Akif Eskalen, a plant pathologist at University of California, Riverside, said the beetles likely reached California through wood shipping and packing containers.

The beetles damage trees by making tunnels in the trunks of them and carry fungi in their mouths, Eskalen said. The fungi colonize and block trees' vessels that carry water from their roots to their leaves, causing branches to die.

"They grow fungus, they feed on fungus and the fungus is a pathogen in the plant," Eskalen said.

The beetle, native of southeast Asia, has become widespread across SoCal. Eskalen brought about 52 scientists from the American Phytopathological Society, who are in California for the organization's annual meeting, to show them the damage the beetles caused to Pasadena trees.

In 2012, researchers from UC Riverside found a beetle carrying the disease referred to as "Fusarium Dieback" on a backyard avocado tree in Los Angeles, Eskalen said. His lab has been conducting experiments to find a way to control the beetle and the fungi and hoping for results by next year.

Eskalen said if SoCal residents notice symptoms of the beetles, including staining on tree trunks or entry holes about one millimeter in diameter, they should alert their local authorities.

"We'd like to know where these beetles are," Eskalen said. "When you have a heavily infested tree, find an expert and find out if your tree needs to be removed or not."

Eskalen said if a tree needs to be removed, the branches should be chipped into pieces less than one inch in size to control most of the beetles. The rest of the material should be covered with clear plastic for a few months and not moved from one location to another, to prevent the beetles from moving.

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