As noted in the
Plum Bud Gall Mite (PBGM) Fact Sheet, this is a fairly new pest in California, and there aren't tested treatment options available. However, a CDFA
pest rating proposal for the plum bud gall mite says, “The galls appear to have little or no impact on stone fruit trees in this state.” It later states, “The impact to stone fruit has been minor and apparently limited to the presence of galls. Fruit production and general tree health do not appear to be impacted.”
The Santa Clara County Department of Agriculture doesn’t require residents to report that they have PBGM anymore. Their advice as of December 2024:
- If a resident has PBGM, cut it out, put it in a plastic bag or cover it with a tarp, and solarize it before opening the bag or uncovering and putting the green waste in their city collection bin. Solarization recommendations for the invasive shothole borer can be used.
- As far as treatments go, constant monitoring of trees is required. When the crawlers emerge, that’s when you can spray with an insecticidal oil to kill them.
- If sharing budwood, only share if there are no mites on the property.
Note that UC advocates using the Integrated Pest Management Process (IPM) for dealing with garden pests. The process provides a balanced approach between managing pests and caring for the environment. It starts with identifying which pests are present, how many there are, and what damage they’ve caused. Once that’s known, a decision can be made as to whether to take any action and, if so, what to do.