Protecting Peñasquitos Oak Trees



The pink ribbons dangling from trees in Los Peñasquitos Canyon Preserve signify a fight against goldspotted oak borers.

If you’ve ever been to Los Peñasquitos Canyon Preserve, you’ve likely appreciated the oak trees. Perhaps not by name or out loud, but these lovely trees bring welcome shade on hot sunny days. 

If you’ve been to the preserve lately, you’ve likely noticed pink ribbons dangling from many an oak. That’s because beetles called goldspotted oak borers (GSOB) have taken up residency. The giant California live oaks that we often take for granted are threatened. 

According to the Friends of Los Peñasquitos Canyon Preserve, this issue was discovered in 2018 and they estimate the beetles had been spreading in the area for a few years. Firewood is the most common source of GSOB arriving in new locations. They think firewood near Peñasquitos probably came from Julian, which was the first area in California to be infested. And that infestation has been traced to firewood imported from Arizona, where GSOB are native.

Aguilar Plant Care has been contracted to spray the affected trees, which happened last weekend. These efforts will not eradicate the invasive species, but the goal is to reduce the spread and death of trees.

Los Peñasquitos generally is home to mule deer, bobcats, coyotes, and raccoons, just to name a few mammals. You may see all kinds of birds including aquatic ones such as great blue herons, egrets, and mallard ducks. There are Pacific tree frogs, crayfish, and even largemouth bass. It’s an amazing jewel of San Diego with water cascading through volcanic rock and meandering beneath a forest of mature California live oaks. Without the oak trees, none of it would be the same.

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Thanks to all involved in the efforts to preserve the oak trees and Peñasquitos.

What Can You Do?
•Make sure you don’t bring infested firewood to other areas.
•Contact a professional if you have oak trees that are affected.
•Get involved with organizations such as Friends of Los Peñasquitos Canyon Preserve.

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Nicki Miller
Nicki Miller
Nicki Miller, co-editor of Bluedot San Diego and Bluedot Santa Barbara, has been creating content and editing for more than 20 years, working at The Washington Post, Martha's Vineyard Magazine, Women's Running Magazine, and San Diego Humane Society. Nicki wants to contribute to a more eco-friendly world and has a particular interest in articles about taking care of people and animals, and how that leads to a healthier planet.
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