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How to prune trees

February 2, 2013

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When cold temperatures keep you indoors, it is the perfect time to tackle pruning chores.

Most trees and shrubs respond best to severe trimming if done during winter before new growth begins. Pruning at the wrong time of year will not kill, but it may result in damaged, weakened or misshapen plants. Also, oak trees are highly susceptible to deadly oak wilt disease if not pruned on a cold winter day*.

Reasons for pruning are: to train the plant, to maintain plant health, to improve the quality of flowers, fruit, foliage or stems or to restrict growth. The need to prune can be almost eliminated if you select the proper plant for the location. Tip: Site plants according to their size at maturity.

By making pruning cuts in a certain order, the total number of cuts can be reduced, which reduces the possibility of plant damage.

First, remove dead, broken or diseased limbs by cutting them at the point of origin or back to a strong lateral branch or shoot. (A lateral branch originates from the main trunk.) Also, remove any water sprouts, which are vigorous shoots arising from the trunk or older branches. These shoots generally do not develop into desirable limbs.

Next, make training cuts as needed. Plants are “trained” by cutting back lateral branches, which helps the plant to develop a desired shape. This type of pruning may be done to help a plant fill in areas opened by storm damage or to keep a plant in bounds when it begins to overtake a space.

The final step in pruning a tree or shrub is to make corrective cuts to eliminate weak or narrow crotches (angles that develop between two connecting branches) and remove the less desirable central leader where double leaders occur. A central leader is the main stem of the tree from which other branches develop, generally the trunk.

There are varied opinions about dressing pruning wounds. The latest science shows that wound dressings do little to prevent damage or disease. Pruning paint can actually slow the healing process so they are not generally are not recommended. The exception is oak tree wounds. Where oak wilt disease is prevalent, such as in North Central Texas, wound dressing should be used. It helps to prevent bark beetles from spreading the disease from tree to tree through cut surfaces.

MAKE CUTS CLEAN

Make cuts clean and smooth to encourage rapid healing. Using sharp, clean pruning equipment will help you to make clean cuts. Avoid tearing the bark when removing large branches. Do not leave stubs. Doing so may cause die back, which is the dying back of stems due to adverse weather conditions, insects, disease or other causes.

When pruning, it is advisable to cut back each stem to a bud or branch. Generally, a plant’s bud arrangement determines its growth habit. The position of the last pair of buds determines the direction in which a new growth shoot will grow. Buds on top of the twig will probably grow upward at an angle and to the side that buds are directed. Buds pointing to the outside of a plant are more desirable than buds pointing to the inside. By cutting to an outside bud, new shoots will not grow through the interior of the plant.

When cutting back to an intersecting (lateral) branch, choose a branch that forms an angle of no more than 45 degrees with the branch to be removed. Also, the branch that you cut back to should have a diameter of at least half that of the one to be removed. Make slanting cuts when removing limbs that grow upward; this prevents water from collecting in the cut and expedites healing.

To open a woody plant, prune out some of the center growth and cut back terminals (tip ends of branches) to the buds that point outward. In shortening a branch, cut it back to a side branch and make the cut a half-inch above the bud. It the cut is too close to the bud, the bud usually dies. If the cut is too far from the bud, the wood above the bud usually dies, causing dead tips on the end of the branches. If more side branching is desired, remove the tips of all the limbs.

*Note: Oak trees should only be trimmed on the coldest days of winter or hottest days of summer.

Resources: AgriLife Extension, USDA Forest Service

Horticulture questions? Call the Texas AgriLife Extension, Hood County, 817-579-3280.

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Category: Horticulture Archived