Proper evaluation of tree damage vital to decisions

Sunday, December 16, 2001

A storm can leave trees looking like there's no tomorrow. Major limbs may be broken or damaged, foliage can be shredded or stripped or the bark may be torn or gouged. But what at first glance may look like mortal wounds are not necessarily fatal to a tree. Trees have an amazing ability to recover from storm damage.

Before writing off a damaged tree as a "goner," homeowners should evaluate the trees by asking the following questions.

Other than the storm damage, is the tree basically healthy and vigorous? If the tree is basically healthy, is not creating a hazard and did not suffer major structural damage, it generally will recover if first aid measures are applied immediately after the storm.

Are major limbs broken? The larger a broken limb is, the harder it will be for the tree to recover from the damage. If a majority of the main branches are gone, the tree may have little chance of surviving.

Has the leader been lost? The leader is the main, upward-trending branch on most trees. In species where a leader is important to upward growth or desirable appearance, it may have to be a judgment call. The tree may live without a leader, but at best would be a stunted or deformed version of the original.

Is at least 50 percent of the tree's crown (branches and leaves) still intact? This is a good rule of thumb on tree survivability. A tree with fewer than half of its branches remaining may not be able to produce enough foliage to nourish the tree through another season.

Is the tree a desirable species for its location? If the tree is in the wrong location, such as a potentially tall tree beneath a power line, or an undesirable species for the property (messy fruit or other such characteristics), it may be best to remove it if it has suffered serious damage.

The questions listed above will help you make informed decisions about your tree. In general, the answer as to what to do about a particular tree will fall into one of three categories.

It's a keeper

If damage is relatively slight, prune any broken branches, repair torn bark or rough edges around wounds and let the tree begin the process of wound repair. A mature shade tree can usually survive the loss of one major limb. The broken branch should be pruned back to the trunk (avoid cutting into the branch collar). In the months to follow, large wounds should be closely monitored for signs of decay.

A basically healthy tree that suffers minor damage, such as several broken branches, may survive if enough strong limbs remain. Young trees, especially, can sustain quite a bit of damage and still recover quickly. If the leader is intact and the structure for future branching remains, remove the broken branches and let the tree close over the wounds to begin recovery.

Wait and see.

If a valuable tree appears to be a borderline case, resist the temptation to simply cut it down and be done with it. In such cases, it may be best to stand back for a while and think it over. Remember that time is on your side. After careful pruning of broken branches, give the tree some time to recover. A final decision can be made later.

Resist the temptation to prune too heavily. Remember that the tree will need all the foliage it can produce in order to make it through the next growing season. Remove only the damaged limbs, then wait to see what happens.

A healthy mature tree can recover even when several major limbs are damaged. With large trees, a professional arborist should be brought in to assess damage on a borderline situation and to safely accomplish needed pruning and branch removal.

Say goodbye

Some trees simply can't be saved or are not worth saving. If the tree has already been weakened by disease, if the trunk is split or more than 50 percent of the crown is gone, the tree has lost its survival edge.

An otherwise healthy young tree that has lost too much of its crown will probably not be able to grow enough new branches and leaves to provide needed nourishment and will never be able to regain its former beautiful shape.

A tree with a rotten inner core in the trunk or structural weakness in branching patterns can cause a split trunk - the tree equivalent of a heart attack. The wounds are too large to mend and the tree has lost its sap lifeline between roots and leaves. Such a tree is all but dead.

Some of your trees may have damage that's too close to call, or may have hidden damage.

To help with questions, a tree professional may be needed. Don't hire just anyone who shows up at your door following a storm. Look for qualified arborists in the phone book or contact your state or city forester.

Joe Garvey is a district forester with the Missouri Department of Conservation.

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