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As I write this article we have received at least three snowfalls, the last one accumulating more than 20 inches of snow. We also have had temperatures close to twenty below.

While it is a good idea to get heavy snow off of some evergreens, one must be careful not to damage or break the branches. When the temperature hovers around zero, the branches can become quite brittle. Even though the evergreens bend down, they usually resume their normal position as they come out of dormancy in the spring.

Speaking of trees, this is the time of the year to prune some trees. There should always be a reason for pruning. For a young tree, its need for pruning will vary at each stage of development. When the tree is young, you should establish its basic structure by eliminating double leaders, weak crotches, and conflicting and inward growing branches.

Older, established shade trees require less pruning. At this stage, you should prune only for corrective purposes such as branches or limbs that are damaged, dead, or dying. Secondary branches that are crossing other limbs and rubbing together should be pruned also. That can cause bark damage that invites disease and insects. Although pruning is necessary for a mature tree, it can be a severe shock to a tree. Be sure to have a reason for every cut. This is why most shade trees should be pruned during the dormant season.

Oak trees should be pruned during December, January, and February to minimize the chance of oak wilt infection. Some feel that birch trees should not be pruned until late summer or early fall to avoid exposing the trees to a very nasty pest called the bronze birch borer.

Short-needled conifers that grow continuously through the growing season can be pruned at any time, but early in the growing season is usually the best. This includes junipers, white cedar or arborvitae, yews and hemlocks. Although the spruce, fir, and douglas fir don't grow continuously, the time for pruning them is not critical. However, pruning in late winter or before growth begins is probably best.

Pines only put on a single flush of tip growth each spring and then stop growing. Prune before these "candles" of new needles become mature. Pines do not have lateral buds, so removing terminal buds will take away new growing points for that branch. Eventually, this will leave dead stubs. Pines seldom need pruning, but if you want to promote more dense growth, remove up to two-thirds of the length of newly expended candles. Don't prune further back than the current year's growth.

Some species such as maples, walnuts, and birches may bleed when the sap begins to flow. This is not harmful and will stop when the trees leaf out. It is still too early in the year to prune fruit trees. They can be pruned in March when the coldest part of the winter is over. There is still plenty of time for the tree to heal before the growing season arrives.

Please note that there are three publications available at the Extension Office regarding pruning trees. They are: Pruning Trees and Shrubs, Pruning Fruit Trees, and How to Prune Trees.

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