Seeking California Citrus Growers With Roof Rat Problems

Len Wilcox California Corner, Pests

Adult roof rat
(Photo by Jack Kelly Clark)

Researchers from the University of California (UC) Cooperative Extension and UC Davis are beginning a two-year study to develop an effective management program for removing roof rats from orchards. The researchers are looking for growers who will allow the UC to work in their orchards to test methods for monitoring roof rat activity.

Roof rats can run rampant and cause substantial damage in California orchards, according to UC Agriculture and Natural Resources (ANR) scientists.

“Roof rats are burrowing and nesting in the ground where they’re chewing on irrigation lines, causing extensive damage,” said Rachael Long, UC Cooperative Extension advisor, in a 2018 ANR news release. “They are also nesting in citrus trees, feeding on the fruit and terrifying field workers when they jump out as people are picking fruit. The chewing pests are also girdling citrus limbs, causing branch dieback.”

The researchers will study movement patterns of roof rats in orchards to learn where rats are spending their time and how far they move daily. This information will provide the framework to then test the efficacy of various management tools for removing roof rats from orchards.

Any grower interested in participating in this study should contact UC Research Associate Ryan Meinerz ( or 530-300-5002) for additional details.

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About the Author

Len Wilcox

Correspondent at Large for Citrus Industry Magazine and AgNet West