Voles and Linden Trees

Voles are a problem in some areas and they can be difficult to get rid of.

Voles look like mice with short tails. They create den holes in the ground and runways under the grass connecting the den holes. Stephan Morris/Shutterstock

Q: Last year, our yard was infested with voles. They ate the bark off several shrubs during the winter. We called someone to take care of this problem. They came out and sprinkled some poisoned food down in the vole holes and in their tracks. We spent about $300 for this first-time procedure, and then the company wanted $49 a month to do any additional treatments. So we did that for three months. They got rid of the voles.

The winter has passed, and now the voles are back. We don’t want to spend another $400 or $500, but we certainly want to get rid of the voles. Is there anything we can do? Are there any products on the market that consumers can buy to get rid of these little critters? We would certainly appreciate your advice.

A: As you know, voles look like mice with short tails. They create den holes in the ground and runways under the grass connecting the den holes. These runways sometimes become visible if there are lots of voles or if the grass above them dies back a little.

They reproduce rapidly and are eaten by many predators, so they are an important part of the natural ecosystem. In fact, they have been called the “Big Mac of the prairie.” If your property is near a prairie, meadow, or other natural area, you will be resupplied with more voles whenever you remove them from your property, no matter how you kill them.

Several poison controls are effective. You can check out a poison bait system at VoleControl.com. The problem with poisons is that you could be poisoning the natural predators or any cats or dogs that eat dying or dead voles, so that could become a problem. Repellents that work on odors or sounds are typically ineffective. Traps that have a covering over the top to make them safer for people and pets are also very effective.

Q: I have a Redmond linden tree that was planted eight years ago. It sits near a small retention pond, so the earth around it is often wet after a heavy rain. I just noticed a ring around the trunk at ground level (slightly below the mulch) that appears to be decay. Below that ring, the trunk is thicker by over an inch. Above the ring, the trunk looks normal, but it is thinner than below the ring. The tree appears to be healthy and is currently full of live buds.

Is the tree sick? Is there something I should be doing to protect it?

A: The various cultivars of American linden are grafted onto seedling linden trees. My first suspicion is that the graft union is causing the slight bulge around the trunk and that this tissue looks different from the bark above and below that line. Think of the graft union as a sort of scar tissue that is different from either of the tree varieties growing above or below the graft. If you pry this bark with your finger and it appears to be solid tissue—not soft, smelly, decaying tissue—then I would leave it alone and watch the tree to see whether it continues to grow this spring.

Several things can cause damage all the way around a tree trunk at low levels. Lawn mowers, string trimmers, and rodents are the three most common. Damage from any of the three could be fatal if it is all the way around the trunk. Don’t allow grass to grow up to the trunk of any tree. It is practically impossible to cut down or remove the grass without damaging the tree trunk.

There should always be a ring of mulch around the base of a tree. The mulch should not be piled up on the trunk because it can harbor voles and mice that gnaw on the trunk under the protection of the mulch. If the rodents did damage the tree over the winter, it should look like someone whittled away at the tree trunk, and the damaged area should be the narrow section, which does not fit your description as well as the graft union idea.

If the trunk is damaged, the tree will still bud out from moisture stored in the trunk and possibly a little water that continues to make it past the damaged area. The tree leaves will start to grow and then die. There is nothing you can do to fix this problem, although, like I said, I don’t think this is the problem on your tree.

Courtesy of Jeff Rugg