garden q&a: moles don't like plants; voles do
Q: Two years ago, I built a raised garden bed. This year, moles tunneled under the frame and munched on the tomatoes. Any advice to prevent this from happening again?
A: Poor moles! They get in trouble for all kinds of issues that aren't their fault, and you aren't alone in blaming them for your garden's troubles. While it is quite possible that moles are at fault for tunneling under your raised bed, it is impossible for them to be attacking your tomatoes.
Moles are strict insectivores. They eat grubs, slugs, earthworms and other soil-dwelling insects. They do not eat plants. Moles live underground and, in spring and early summer, you'll see their raised tunnels. They also create mounds of excavated dirt. In summer and fall, their tunnels are deeper, and that's why we typically don't see any damage then. Mole tunnels are used as travel routes as well as traps for their insect prey. The damage moles cause is purely aesthetic because they aren't capable of eating plants.
So then, what is eating your tomatoes? It could be voles, which look much like a mouse but with a short tail and small ears. They live in large colonies and feed regularly on plant roots, bulbs, tree bark and even plant tops (though they don't commonly feed on plants such as tomatoes). Their “tunnels” actually are not tunnels at all, but rather well-worn paths in the grass or on top of the soil. They leave no mounds of dirt behind. Voles can be controlled with mousetraps baited with peanut butter (which, by the way, will NOT work for moles unless you bait the trap with a live earthworm or grub ... yuck.). Be careful if you do this, though, as dogs, cats and kids can access the traps, too. Putting the trap in an empty soup can helps shelter it from other non-target critters.
There also are several mole and vole repellents that are reportedly successful and safe. Castor oil repellants (like Mole-Med from www.gardensalive.com) work by applying either a liquid or a granular formulation over the area at regular intervals. You can make your own by putting 2 tablespoons of pure castor oil in one gallon of warm water. Add a few drops of dishwashing liquid and spray all affected areas once a month. Castor oil repellents work for both voles and moles.
I also think that chipmunks could be to blame for your tomato troubles. Though they aren't common garden pests, they have been known to tunnel in gardens and eat the occasional vegetable. Watch the garden carefully come spring because if chipmunks are the culprit, they are far more easily seen than voles or moles. They can be trapped in live traps (www.havahart.com) baited with sunflower seeds.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her website is www.jessicawalliser.com.
Send your gardening or landscaping questions to firstname.lastname@example.org or The Good Earth, 503 Martindale St., 3rd Floor, D.L. Clark Building, Pittsburgh, PA 15212.