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How to keep rodents and deer from snacking on your tree (and how to repair the damage if they do!)

How to keep rodents and deer from snacking on your tree (and how to repair the damage if they do!)

Heidi Wechselberger |

Deer, rabbits and mice have a tough time finding food until everything has thawed in the spring. Until then, they have to eat…and some of the easiest treats to find are in your garden.

This is great news for hungry critters, but not for your trees! Animals peel tree bark off in strips to eat, which can ultimately kill your tree. You can treat the damage, but we think the best practice is to try to prevent it from happening in the first place. Here’s how:

Protect the trunk with tree guards

Young, tender, trees are the most attractive treat, and the most at risk for permanent damage. For these trees, we recommend putting plastic tree guards on in the fall to prevent animals from nibbling on the trunk.

Make sure the tree guard is tall enough to extend 50cm past the highest point you think the snow could accumulate to over the winter. Otherwise the animal might still be able to reach its target when standing on top of the snow.

Larger trees can have their trunks wrapped with burlap, which will stop deer from being able to do a lot of damage to the trunk itself. It doesn’t stop them from eating the branches though. Deer usually leave larger trees alone because the bark is just not as tender as that on younger trees, or as easy to remove.

Apply repellents

Discourage deer, mice and rabbits from treating your garden like an all-you-can-eat buffet with repellents designed for that purpose. Most contain Thiram, which is bitter to the taste and makes your garden bounty much less appetizing to uninvited guests. They come in liquid or pellet form and are very easy to use.

The best time to apply them is late fall, when trunks and branches are dry, leaves have fallen and temperatures are still above freezing. Read the label carefully before use, as some products should not be used on fruit trees if anyone intends to eat the fruit.

Repair the damage

Deer and rodents damage trees in two ways: by stripping bark off the trunk or larger branches; and by doing a little unauthorized pruning (nibbling the ends off branches.)

The damage done to ends of branches is mostly cosmetic. Just tidy up chewed branch tips with sharp, clean pruning shears and you may not even notice the “adjustments” once the tree leafs out.

Damage to the trunk is more serious. The good news is if the damage is less than 25% of the trunk’s circumference, your tree will likely survive. You can try to protect the wound with a sealant, which makes it more difficult for insects and fungi to enter the tree in the spring, but chances are the tree will heal itself without your help.

If the wound extends more than 75% around the trunk of your tree, you may be looking at replacing it. Call a certified arborist if you’d like to know for sure.