Q: Here is a picture of what something is doing to our lawn. Can you identify the culprit, and can you tell us how to get rid of it? We find the diggings but no sign of holes. Help!
Ahmed Alei, Sacramento
A: As soon as you notice mounds of soil appearing on your property, whether they are in your lawn, your vegetable garden or orchard, begin to search for the cause, according to UC master gardener Annie Kempees. Two possibilities in this case would be the mole and the pocket gopher.
The mole (Scapanus species) is a small insect-eating mammal. Contrary to a commonly held belief, it isn’t part of the rodent family. In California, moles inhabit the Sierra Nevada, coastal range mountains and foothills, and the entire coastal zone. They aren’t usually found in the dry southeastern regions of the state or in much of the Central Valley, except for moist areas where the soil is rich in humus, such as riverbanks.
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The California Fish and Game Code classifies moles as nongame mammals. If moles threaten growing crops or other property, the owner or tenant may control the moles using any legal means.
Moles live almost entirely underground in a vast network of interconnecting tunnels. They frequently create shallow tunnels just below the surface where they capture worms, insects, and other invertebrates. Mole mounds tend to be circular around the margin. They may infrequently consume roots, bulbs and other plant material, although rodent species (such as pocket gophers, meadow voles and deer mice) are almost always the cause of such chewing damage.
Methods of mole management include trapping, repellents and baits. Some home remedies will deter moles, however, persistent ones will eventually work around underground barriers and fencing.
Flooding tunnels isn’t recommended. Repellents and frightening devices are not supported by research. Complete information about moles and these management techniques, may be found at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74115.html.
Pocket gophers, often called gophers (Thomomys species), are burrowing rodents that get their name from the fur-lined, external cheek pouches, or pockets, they use for carrying food and nesting materials. Pocket gophers are well equipped for a digging, tunneling lifestyle with their powerfully built forequarters; large-clawed front paws; fine, short fur that doesn’t cake in wet soils; small eyes and ears; and highly sensitive facial whiskers that assist with moving about in the dark.
Mounds of fresh soil are the best sign of a gopher’s presence. Gophers form mounds as they dig tunnels and push the loose dirt to the surface. Typically mounds are crescent or horseshoe shaped when viewed from above. The hole, which is off to one side of the mound, usually is plugged. In irrigated areas such as lawns, flower beds, and gardens, digging conditions usually are optimal year round, and mounds can appear at any time.
Pocket gophers are herbivorous and feed on a wide variety of vegetation but generally prefer herbaceous plants, shrubs and trees. Most commonly, they feed on roots and fleshy portions of plants they encounter while digging.
Pocket gophers often invade yards and gardens, feeding on many garden crops, ornamental plants, vines, shrubs and trees. A single gopher moving down a garden row can inflict considerable damage in a very short time. Gophers also gnaw and damage plastic water lines and lawn sprinkler systems. Their tunnels can divert and carry off irrigation water, which leads to soil erosion.
The California Fish and Game Code also classifies pocket gophers as nongame mammals. Pocket gophers that are injuring growing crops or other property, including garden and landscape plants, can be controlled any time and in any legal manner.
To successfully control gophers, early detection is best. Trapping and/or poison baits are common methods. If you have household pets or small children, poison baits would not be a wise choice.
Successful trapping or baiting depends on accurately locating the gopher’s main burrow. To locate the burrow, use a gopher probe. Probes are commercially available, or you can construct one from a pipe and metal rod. Probes made from dowels or sticks work in soft soil but are difficult to use in hard or dry soils. An enlarged tip that is wider than the shaft of the probe is an important design feature that increases the ease of locating burrows.
To find burrows, first locate areas of recent gopher activity based on fresh mounds of dark, moist soil. Fresh mounds that are visible above ground are the plugged openings of lateral tunnels.
Probe about 8 to 12 inches from the plug side of the mound; the main burrow is usually located 6 to 12 inches deep. When the probe penetrates the gopher’s burrow, there will be a sudden or subtle, noticeable drop of about 2 inches. Because the gopher might not revisit lateral tunnels, trapping and baiting them is not as successful as in the main burrow.
Additional information on controlling pocket gophers (including some videos on how to use the traps), baiting, fumigation, exclusion, natural controls, habitat modification and other control methods can be found at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7433.html.
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 email@example.com. Please put “Garden Detective” in the subject field and include your postal address. To contact UC Extension directly, call:
- Sacramento: (916) 875-6913; 9 a.m.-noon and 1-4 p.m. Monday-Thursday
- Amador: (209) 223-6838; 10 a.m.-noon Monday-Thursday; email ceamador. ucdavis.edu
- Butte: (530) 538-7201; 8 a.m.-noon and 1-5 p.m. weekdays
- Colusa: (530) 458-0570; 9 a.m.-noon and 1-4 p.m. Tuesdays; website: cecolusa.ucanr.edu
- El Dorado: (530) 621-5512; 9 a.m.-noon Tuesday-Friday
- Placer: (530) 889-7388; 9 a.m.-noon Tuesday-Thursday or leave a message and calls will be returned; website: pcmg.ucanr.org/got_questions
- Nevada: (530) 273-0919; 9 a.m.-noon Tuesday-Thursday or leave a message
- Shasta, Tehama, Trinity: (530) 225-4605
- Solano: (707) 784-1322; leave a message and calls will be returned
- Sutter, Yuba: (530) 822-7515; 9 a.m.-noon Monday-Tuesday and 1-4 p.m. Thursdays
- Yolo: (530) 666-8737; 9-11 a.m. Tuesdays and Fridays, or leave a message and calls will be returned