How do I get rid of voles and moles in my raised-bed tomato garden?

– Richard Smith, Sacramento

According to UC master gardeners Bill Pierce and Mary Griggs, voles or field mice are relatively easy to control. Controlling moles is more difficult.

Many gardeners tolerate the damage and depend upon the family cat. The use of traps, repellents and toxic baits should be used with care around cats and dogs.

Moles live almost entirely underground in a vast network of interconnecting tunnels. They can eat some roots, bulbs and other plant material, but generally the greatest problem caused by moles is their burrowing, which dislodges plants and dries out their roots.

Mounds and surface runways are obvious indicators of the presence of moles. The excavated soil may be in small chunks and single mounds often appear in a line over the runway connecting them.

Moles can cause significant damage in the garden and lawn. To control, a combination of methods may be necessary.

Trapping is the most universally applicable and dependable method of mole control. Understanding mole behavior determines the way you set your traps.

To be effective, the trap must be set to catch the mole underground. When a mole's sensitive snout encounters a foreign object in the burrow, the mole is likely to plug off that portion and dig around or under the object. Therefore, traps should be set to straddle or encircle the tunnel, or be suspended above it.

In addition to trapping, there are repellents and toxic baits. For extensive information on eradicating moles, go to www.ipm.ucdavis.edu and look for the "Pest Note on Moles," No. 74115.

Voles are collectively called meadow mice. Voles are mouselike rodents somewhat similar in appearance to pocket gophers. Although voles spend considerable time above ground, most of their time is spent below ground in their burrow system.

The clearest signs of their presence are the well-traveled, above-ground runways that connect burrow openings; the runways are usually hidden beneath a protective layer of grass or other ground cover.

Voles are active day and night, year round. They are normally found in areas with dense vegetation. To prevent vole damage, you need to manage the population in an area before it reaches high numbers. This often can be achieved by removing or reducing the vegetative cover.

Monitoring for their presence and modifying their habitat are essential. A wire fence at least 12 inches above the ground with a mesh size of one-quarter inch or less will help to exclude voles from entire gardens.

Trapping, baiting and repellents are also available. For extensive information on eradicating voles, go to the same website listed above and look for "Pest Note on Voles," No. 7439.

These two Pest Notes are also available by sending a self-addressed, stamped business-size envelope to: Pest Notes, Nos. 74115 and 7439, UC Cooperative Extension, 4145 Branch Center Drive, Sacramento, CA 95827.

Garden Tip

• Watch for signs of powdery mildew on roses, grapes and ornamentals, particularly on new leaves. The spores can go through their entire life cycle in 72 hours. Powdery mildew hates water, but loves new growth and warm weather – 68 to 77 degrees is ideal. Watering plants in the morning – including a spray on new leaves – can help thwart the spores.

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