Q. When the snow finally melted a couple of weeks ago, we noticed that something has eaten the bark off the trunks of several new crabapple trees and burning bush in our landscape. Is there anything we can do to save these plants?
A. Deep, persistent snow cover this winter has provided a haven for hungry meadow voles and field mice as they feed on the bark of many trees and shrubs right at the soil line. At the same time, crusted snow has allowed rabbits to feed on the bark of the same plants two, three and even for feet off the ground.
The good news, if you can call it that, is that most multiple-stemmed shrubs including redtwig dogwood, burning bush, viburnums, rhododendrons, etc. can recover from this type of wildlife damage. New buds just below the feeding damage will emerge (at the tip of my thumbnail in the photo at left), and within a couple of months a number of new shoots will have grown several inches to more than a foot in length (below, at right)!
Simply cut these plants back to a point just above the new shoots. Though drastically reduced in size, these plants will gradually regain their previous size and form, as if they'd undergone intentional "rejuventation" pruning!
On the other hand, single-trunk fruit and ornamental trees will gradually decline and eventually die if most or all of the bark has been eaten from around the entire trunk, at left. Carbohydrates (plant food) produced in the leaves of damaged plants will not be able reach the root system because the transport tissue (phloem) immediately beneath the bark will have been eaten, too! In fact, it's this sugar-containing tissue that the critters prefer.
The only chance for saving a girdled, single-trunk trees is to perform a “bridge” graft. Good pictures and an explanation of this technique has been prepared by M.E. Ferree and Gerard Krewer, Extension Horticulturists at the University of Georgia and can be found by clicking here. However, since bridge grafts can be tricky to perform, recommend that you hire a certified nursery professional or certified arborist to perform the procedure if the damaged plants are extremely valuable.
You can reduce the chance of this type of damage to plants in your landscape in the future by enclosing the trunks of young trees in protective cylinders fashioned from ¼ inch mesh hardware cloth or plastic drainage pipe, at right. Bury the bottom of the cylinders under several inches of soil to prevent mice and voles from burrowing under them. Also make the cylinders tall enough to cover the trunk all the way up to the lowest set of branches to prevent rabbits from getting at the bark while perched on top of crusted snow that may be several feet deep.
And, finally, as tired as you may be after shoveling out your driveway and sidewalks, it’ll also be a good idea to wade out and shovel the snow away from the base of valuable single-trunk trees in your landscape. Mice and voles will not feed as heavily on exposed trunks, and rabbits won’t be able to gnaw on branches above the hardware cloth or drainage pipe barriers while perched on top of a snowdrift.