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Tiny Beetle Kills Trees, Ups Fire Risk

beetle shot borer el cajon trees park

A tiny beetle is so widespread in California that lawmakers, concerned for the safety of millions of trees, are looking for a way to stop its destruction.

New efforts are now underway in San Diego County to stop the spread of the shot hole borer.

The beetle has already wiped out thousands of willow trees in the Tijuana River Valley Regional Park and has infested trees at San Elijo Lagoon Ecological Reserve in Cardiff-By-The Sea.

Park rangers said the tenacious beetle seems to target trees along waterways. However, its destruction is widespread.

“This bug does not discriminate against any trees,” said Flinn Springs County Park Ranger Patty Heyden. “It’ll hit any tree that is around.”

Heyden and rangers in El Cajon removed a sycamore tree infested with the beetle.

The shot hole borer, which is smaller than a sesame seed, infiltrates trees with a fungus that quickly spreads under the bark.

“They disrupt the whole vascular system of the tree, the whole water carrying system of the tree,” explained Pat Nolan, plant pathologist at County of San Diego. “And eventually there are so many cuts in them that the water can’t get from the roots up to the top of the tree.”

Discoloration and wet stains on the bark and branches are signs of infestation.

Nolan said the insect’s presence is often not noticed initially. “If you start counting, there could easily be 30, 40 thousand holes in a tree.”

Rangers believe the pest was somehow transported through a wood shipping crate from Southeast Asia to Southern California.

Currently, rangers are not able to contain the beetle’s spread. The shot hole borer has no native predator and no cure exists for the fungus.

State lawmakers are now taking up the fight to eradicate the tiny pest.

This legislative session, Assem. Lorena Gonzalez-Fletcher (D-80) introduced Assembly Bill 2054, which sets aside $5 million to create a coordinated, statewide plan of attack.

“Dead trees of course in a summer season is a recipe for wildfire,” said Gonzalez-Fletcher. “That’s one of the huge concerns, I think, especially in our eastern portions of the county.” 

Local parks also have a strategy for the fallen trees.

“When we remove a tree, we chip up the bark and we solarize it. We pile it up, we put clear plastic on it, let it set for a year and let it cook, and that helps destroy the larvae,” explained Heyden. “Then we use it for mulch and it returns to the earth.”

At Flinn Springs County Park, rangers and volunteers have planted nearly one hundred trees to make up for the trees that died after becoming infested.

At Tijuana River Valley Regional Park, rangers plant at least three trees for each one that’s removed.

But the new trees can’t grow more quickly than the destructive pest, which experts estimate could kill millions of trees in Southern California.

“Everybody is in danger of losing their trees to this bug,” said Heyden. “It’s a scary thing. It really is.”

Photo Credit: NBC 7
Source: NBC San Diego

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