Prevent winter damage to trees, shrubs

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The polar blast that started last week has left us with temperatures 20 to 30 degrees below normal for November. This year, it’s even more important to take steps to protect your trees and shrubs from winter damage. University of Minnesota Extension officials offer these tips.

Animal damage

Deer, rodents, mice and other animals can feed on tender parts of trees and shrubs throughout the winter. Deer can cause extensive damage when the rub their antlers on trees.

Rodent damage can be minimized by wrapping 1/4-inch mesh hardware cloth around the trunk. It should be 18 to 24 inches higher than the snow line. This cloth can be left on year-round if you leave some room to allow for growth.

A repellant such as thiram, a common fungicide, can be sprayed on trees and shrubs to repel both rodents and deer. You’ll need to reapply it after heavy snow or rain. To make thiram more effective for deer, dip heavy rags in the repellant and hang them in the trees.

Frost heaving

As soil freezes and thaws between fall and spring, the soil expands and contracts. This can push new plantings and shrubs out of the ground, and damage roots. Place a 4- to 6-inch layer of mulch around your plants and shrubs to keep soil temperatures more constant.

Sun scald

Sun scald on ash (left) and spruce trees.

Sun scald

Dried, cracked, or sunken areas of bark on a tree, especially on the south or southwest side, is a sign of sun scald. Newly planted or young trees are most susceptible, as are thin-barked trees: cherry, crabapple, honey locust, linden, maple, mountain ash, plum.

You can prevent sun scald by wrapping the trunk with a commercial tree wrap, plastic tree guards or any other light-colored material in fall. This will reflect the sun, which keeps the bark at a more constant temperature. Remove the wrapping in spring after the last frost.

Salt damage

If you have trees and shrubs planted near streets or pathways where salt is used to clear ice, the salt can damage your plants. Even if you don’t use de-icers on your property, salt can be sprayed onto plants by passing cars or absorbed from runoff where salt was used.

Placing a burlap screen between the plants and the salty areas will help protect plants from salt spray.

“Even though plants respond differently to winter stress and each winter provides a different set of stressful conditions, plants possess a remarkable ability to withstand extremely severe winter conditions,” UM Extension officials say. “Minnesota winters should not discourage planting of traditional or new plant species.”

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