More results on a non-toxic treatment for oakworm infestations in coastal California

4 12 2025

Last year I shared a post on a non-toxic treatment for oakworm infestations here on the Central Coast of California. In that post I stated:

“In 2017 there was a severe oakworm infestation of coast live oaks in the Monterey region and elsewhere. I’m often contacted at these times by property owners concerned about their oaks. Many wish to spray the trees with insecticides to reduce the infestation. Upon my advice, I tell property owners that spraying chemical insecticides is not necessary for the oaks to recover from these infestations, provided they are given proper care. Since the oakworm infestations are related to a lack of cultural fires, which controlled their populations in the past, a way forward is to emulate fire effects on the forest ecosystem.

Thus, rather than using chemical sprays as is typically recommended by arborists, I prefer using fire mimicry treatments to oak trees infested with oakworm. In the present case study I recommended to the property owner to do fire mimicry treatments instead of spraying the oaks. Never knowing for sure, I explained to them that the oaks would likely recover from the infestation, and that they would show continued improvement in the following years. A second set of fire mimicry treatments were preformed the following year (2018).”

The repeat photo sets shown last year and the new ones from this year indicate that the oaks have continued to maintain healthy canopies following the 2017 oakworm infestation.


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