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Our trees and shrubs have gone through a lot this past summer. We have seen heavy rain, and the lack of rain. There have been some very hot days and stormy nights. I wrote earlier this year that one of my tall elm trees was struck by lightening and I’m waiting to see how it comes through the winter.

Speaking of winter, even a mild winter can take its toll on young trees and shrubs. One of the easiest things you can do to help your ornamental trees and shrubs is to make sure they are thoroughly watered before the ground freezes. Even if the fall is rainy it may not be enough for young trees and shrubs.

Adequate moisture is especially true for evergreen because they need moisture all winter long. Water serves as a buffer against low soil temperatures by holding heat in the soil. Also, serious root damage can occur in dry soils where the frost penetration will be deeper and the soil temperature lower.

Now is the time to apply a mulch around your trees and shrubs. Use two to four inches of wood chips or bark over the root zone to help retain moisture and maintain a more constant soil temperature. Keep the mulch a couple of inches from the trunk as it may cause the bark to stay moist and decay.

Winter burn is a real problem for yews, hemlock, arborvitae, and other evergreens. This bleaching or browning of the foliage usually occurs on the south, or windward side, but in a severe winter the whole plant may be affected. It is caused by the sun heating the needles until they begin to transpire which causes them to release moisture. Terry Yockey, who gardens in Red Wing, suggests that you protect them from winter sun and wind by building a temporary screen. Drive four wooden stakes into the ground around the plant and wrap the stakes with burlap and staple it to each corner. For large shrubs and two-sided, V-shaped windbreak should work. Point the V to the south, southwest, or in the direction of winter winds.

Sunscald is another common winter problem, especially for young, thin-barked trees. On cold days, the sun heats up the bark which stimulates tissue activity. When the sun goes under a cloud, the rapid temperature drop kills the active tissue, causing a cracked area of dead bark. The best protection against sunscald is to use loose-fitting, plastic tree guards until the tree becomes older when it will have a thicker bark for insulation.

The stretchy tree wrap is no longer recommended because it is not always effective at preventing sunscald. Also, tree wrap does not protect the tree from insect entry, but rather encourages insects to burrow underneath it.

Many times people leave the wrap on too long in the spring which causes moisture to be trapped between the wrap and the trunk. This creates rotting and potential insect problems.

Rodents such as rabbits and mice can also cause serious damage to the bark of young trees. To prevent the girdling of your trees is to us a cylinder mesh hardware cloth and place it around the trunk. It should extend two to three inches below the ground to keep the mice and voles from burrowing underneath, and at least 18 inches above the anticipated snowline to keep the rabbits away.

I’ll end the article as I began––be sure to keep watering the young trees and shrubs until the ground is frozen. Keep a gallon jug of water outside and when it freezes you can stop watering.

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In Your Yard and Garden

Wait until the ground freezes to mulch. Have material set aside. If it snows before the ground freezes, it's ok to mulch over the snow. Strawberries should be mulched with straw soon. The ground typically freezes by mid-November. Use clean (weed free) hay or straw. Raking leaves from the yard is not advised as the leaves will mat too much. You can use bagged leaves as mulch because the bags will keep the leaves from getting wet and matting down.

Fall bearing raspberries can be pruned back after fruiting but research has shown that later winter/early spring pruning is best. The nutrients stored in the canes are re-absorbed by the roots.

Clean up fallen fruit and leaves. Destroy diseased plant material. Do NOT compost it. Resist the urge to prune fruit trees after harvest. Wait until late winter or early spring for this task.

Ways to Access Information

•The voice mail is checked year round. Leave a message at 651-674-4417, ext. 18, and a Master Gardener will return your call.

•www.extension.umn.edu/county/chisago Check out the 'Hot Topics' box in the middle of the page for current Chisago County Master Gardener news and events.

•You can also click on 'Ask a Master Gardener' next to the cute little flower on the right hand side of the page. Here you can search 1000's of answers from Master Gardeners around the state. If you don't find your answer you can submit a question online or search for University publications.

•Bell Museum of Natural History

•For information about snakes, skunks, raccoons or other wildlife around your yard, call the wildlife information line at (612) 624-1374 or www.bellmuseum.org.

•To see the latest Yard andGarden newsletter, go to: http://www.exten sion.umn.edu/yardandgarden/YGLNews/YGLNews.html.

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