Proper pruning will ensure healthy trees in your landscape

Published: Sunday, Nov. 27 2011 4:00 p.m. MST

A previous column on pruning left many unanswered questions, so I wanted to follow up with some additional advice. Remember, these tips apply to shade trees, not fruit trees, as they are both pruned very differently.

Fruit tree are pruned every year to force the tree to produce a good crop of fruit What seems like extreme pruning opens the tree up to the sunlight, which helps produce quality fruit.

Shade trees, by contrast are aesthetic additions to our landscapes. They do not need heavy pruning to force growth that is going to produce abundant blossoms.

As long as a shade tree grows to its natural form, the only pruning we need to do is to eliminate defects.

This corrective pruning is best done while the trees are young and you are standing on the ground or a very stable short ladder.

Starting with a definition of proper pruning may give some helpful advice.

"Proper pruning" means the removal of living, dying and dead parts of the tree for the benefit of the tree, surrounding plants and people.

Now is a good time to assess your leafless deciduous trees for any defects that are readily apparent and are easier to correct.

While many gardeners are reluctant to prune their trees, remember that trees can grow new branches if some are removed. Trees do not have a nervous system that feels pain as ours does.

There is no need to give the tree aspirin or other painkillers or use an anesthetic when we prune. Although there are many pruning paints and wound dressings on the market, save your money. Wound dressing encourage the wood to decay as trees are incapable of healing.

Pruning is never a substitute for selecting and correctly planting the right tree. Excessive pruning to radically alter a tree's natural shape or to drastically reduce its size is an exercise in futility.

Start pruning only what needs pruning early in the life of the tree.

This will establish the desired structure for future growth. Most nurseries try to sell quality plants that are well-grown, but as with any thing that is alive, trees do not always cooperate.

The following defects need to be eliminated by corrective pruning on young shade trees.

Narrow or "V" shaped branch angles or crotches are going to severely weaken a tree. The reason is that the wood does nogrow or knit together. It touches, but the narrow V fills with debris and old bark.

Once these branches are under stress from snow, wind or other forces, the crotch splits and the tree is destroyed.

The solution is to cut out one of the stems. The longer you delay pruning, the worse the problem becomes and the harder it is to correct.

For most species of deciduous trees, the strongest branches are attached to the trunk at about a 45-degree angle. Some upright trees come off at much narrower angles, while evergreens come off at about 90 degree angles.

Water sprouts are another type of undesirable branches. These vigorous, very upright shoots grow in the interior of the tree and quickly interfere with the growth of the desirable branches.

Cut these down to the base as quickly as possible — or even better, rub them off when they are only a couple of inches tall in the summer. Water sprouts also attract insects and are prone to disease.

Crossing or rubbing branches are also problems.

Tree bark protects the tree much like your skin protects you. Branches that rub open the bark and allow insect and diseases to invade. Remove these problem branches as soon as possible to prevent infections or other damage.

Never cut the central leader or trunk of a well-formed tree unless you are trying to force low-branched trees or multiple-stemmed plants. Cutting the branches or topping the tree stimulates many trunks to grow.

Some grafted trees are prone to suckering. These sprouts come up around the base of the tree and interfere with the beauty and natural tree growth. Use a sharp knife to cut them off as close to the roots as possible.

No matter what type of pruning you do, make clean and smooth pruning cuts. Make certain the bark at the edge of the cut is firmly attached to the wood. A few minutes spent now will help prevent serious tree damage in the future.

Larry A. Sagers is a horticulture specialist for the Utah State University Extension Service at Thanksgiving Point.

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