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Still time for winter tree chores

Dreams of a white Christmas seem rather sketchy this year, with our temperatures fluctuating between above freezing to well below freezing. Slick roads and foggy conditions seem to be the norm.

However, these conditions are prime for some winter protection chores that a thick layer of snow would not allow.

One task that could be easily taken care of is wrapping your young, thin-skinned bark trees or your fruit trees. There are two reasons to protect these trees; the first is from rodent or rabbit damage.

These pests will chew the tender bark at the base of the tree during the winter months as a source of food, causing damage to critical plant tissue. The tree's bark layers contain critical plant tissue that transport nutrients and water up and down the tree. If damage is done to these layers, the tree becomes girdled and most likely will die if it encircles the trunk.

Another reason to wrap or protect young, tender trees is from sunscald.

Sunscald damage often appears as elongated, sunken, dried or cracked areas of dead bark. This damage is most common on the south or southwest side of the trunk. Sunscald is caused on cold winter days when the sun heats up the bark to the point that the cambium layer is stimulated and activity occurs. Once the temperature drops quickly due to the sun setting, or even cloud cover, the cambium tissue that became active is suddenly killed.

Tree species most susceptible to sunscald include: cherry, crabapple, honey locust, linden, maple, mountain ash and plum. As the tree ages, the bark becomes more thick and sunscald is not as likely to occur, but young trees should be protected.

To protect your trees from either rodent or rabbit damage or sunscald, simply wrap the trunk with a commercial tree wrap, or slip on a plastic tree guard. Other one-quarter inch or smaller metal mesh material can be placed around the trunk of the tree to protect from rodents or rabbits. When protecting against rodents and rabbits, the material should be placed from the base of the trunk to 18 to 24 inches up the trunk; even higher when snow levels exceed this.

For sunscald, any other light-colored material can be used to protect a tree's trunk. This helps reflect the sunlight and keep the bark at a more consistent temperature.

Regardless of what material you use, be sure to remove it come spring and reapply again next fall. Leaving the material on all year can cause other types of damage during the growing season.

Evergreens also need protection in the winter months to help protect against winter-burn. Evergreen shrubs that are low growing should simply be covered with snow or mulch. Caution that putting mulch on these low-growing evergreens can be challenging to clean out come spring.

For taller evergreens, wrapping with burlap can help reduce the chances of winter-burn as well as damage from heavy snows. However, if evergreens did not have sufficient moisture throughout the growing season and moisture stored for the winter, the needles may still desiccate, turn brown and die.

So take advantage of the lack of snow and take care of any unfinished tree and shrub protection chores you may not have had time to finish a few months ago. The long-term health of your plants may depend on this winter protection.

For more information on winter protection visit www.extension.umn.edu/garden/yard-garden.

Robin Trott is a horticulture educator with University of Minnesota Extension in Alexandria. Contact her at 320-762-3890 or at trot0053@umn.edu.

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