Garden Detective

Thirsty ground squirrels eating drip irrigation lines

Ground squirrels are a common and destructive pest.
Ground squirrels are a common and destructive pest. file photo

Experts tackle readers’ garden questions.

Q: I have ground squirrels that have eaten into most of my drip system hoses. If I were to bury the lead lines, then when I run the spaghetti lines to the plants, they bite them and it’s not really all that noticeable until the plants die. Is there a catch-call solution in dealing with squirrels, short of shooting them? Is it really necessary to run the lead lines inside PVC? Then, I still have the spaghetti line to deal with.

Tim Mero, Folsom

Master gardener Catherine Barkett: Squirrels can be destructive pests. During the drought, they were probably chewing into irrigation lines to find water.

There is no way to completely protect your yard from squirrels, but you can definitely discourage them and minimize the damage they do.

Before you decide on a plan of attack, identify the kind of squirrel you have. For help, check out the University of California’s Pests in the Urban Landscape blog. . Tree squirrels are considered “game” mammals and there are restrictions on catching, trapping and killing them. Ground squirrels are not considered “game” and not protected.

The most complete approach to managing squirrels in your yard will be a multi-faceted, long-term, integrated pest management (IPM) strategy. To make your yard less attractive to squirrels, increase the number of predators. A tall pole on your property may attract hawks. Most dogs and cats, even if they never catch a squirrel, chase and annoy them. Owl decoys may be helpful if you move them frequently enough that the squirrels do not get used to them.

You can also make your property less attractive by removing piles of old wood or dead weeds, which are hiding places for ground squirrels. Some evidence shows that California ground squirrels dislike lush vegetation, perhaps because it gives their predators places to hide.

The United States Department of Agriculture has been researching the effectiveness of physical barriers for keeping ground squirrels out of military sites. These include clear plastic fences, pea gravel trenches, low-voltage electric fences and small-mesh barriers that extend above and below ground. To monitor the results of the research, visit the USDA’s wildlife damage webpage.

Using hard irrigation piping, or anything that will encase and protect the rubber tubing, will discourage squirrels, although, as you note, spaghetti lines are also vulnerable and it is difficult to encase them. PVC pipe, landscape fabric or wire mesh wound all the way around the rubber tubing would discourage ground squirrels from chewing the lines from above or underneath. It is labor intensive, but might be less expensive in the long run than continually replacing your drip lines.

One irrigation specialist recommends giving squirrels their own drip line drinking fountain by putting a saucer under an emitter. It might be worth a try!

For more information on ground and tree squirrels, visit the UC integrated pest management website at ipm.ucdavis.edu and look for Pest Notes 7438 (Ground Squirrels) and 74122 (Tree Squirrels). For information on the biology, identification, regulation and management of ground squirrels in California, read the UC information, www.groundsquirrelbmp.com.

Catherine Barkett is a UC Cooperative Extension master gardener for Sacramento County.

Garden questions?

Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties. Send questions to Garden Detective, P.O. Box 15779, Sacramento, CA 95852. Send email to h&g@sacbee.com. Please put “Garden Detective” in the subject field and include your postal address. To contact UC Extension directly, call:

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