The type of care you give damaged trees should depend on their age, the extent and type of damage, and the time required for surrounding soil to reach normal moisture levels.
A tree's age will largely determine its ability to recover. A young, vigorous tree will be more likely to survive than an older one, though sometimes an older tree's deep roots will help it withstand the force of a flood. In general, a damaged older tree will be weakened more than a young tree receiving the same damage.
Damage to trees may include fallen trees, broken and torn limbs, wounds, split branches, uprooting, weakening and exposed roots.
Plan ahead before deciding what to do with fallen trees. In general, it is best to reset only small trees since large trees will be weakened and may fall again, perhaps damaging property.
Decide what to do with tree stumps. If you are going to leave them, cut them off flush with the ground. If you plan to remove them, leave 4 feet of stump standing. Removal will be cheaper and easier if the stump can be pulled, rather than dug out.
Broken and Torn Limbs
This damage will affect the shape as well as the general health of the tree. Prune the tree properly to avoid additional damage.
- Cut off broken or torn limbs to avoid unnecessary bark stripping. Leave a smooth finish flush with the trunk or branch from which you prune.
- Do not cover the cut surface with a prepared tree paint or wound dressing. These products may trap moisture and disease-causing microorganisms.
- To remove large, heavy limbs, use three cuts to avoid ripping bark and wood.
- Make a cut on the underside of the limb, about 1 foot from the trunk or branch from which you are pruning. Cut only about one-third through the limb.
- Make a second cut on the upper side of the limb, about 2 to 6 inches farther out on the limb than the first cut. Continue sawing until the branch splits off.
- Remove the remaining stub by making a single cut flush with the trunk or branch from which you are pruning.
The amount of damage to the bark of larger shrubs and trees will affect the plant's ability to recover, especially when there is more than one type of injury.
- Remove all jagged and protruding wood. Make smooth, clean cuts with a saw or chisel.
- If the wounds are bark wounds, remove loose bark. To remove bark, make smooth, clean cuts to form a boat-shaped area pointed at both ends.
If branches are split at the crotches, pull them back into place and secure them with lag-threaded screw rods:
- Bore through the trunk or branch above the split where the screw rod is to be inserted. Make the hole 1/16 inch smaller in diameter than the diameter of the screw rod.
- Insert the screw rod until the point is nearly to the opposite side.
- If the split is long, insert as many screw rods as necessary, 12 to 18 inches apart. Or use regular bolts with washers on each end. Countersink the bolt so the washers will rest on the hard wood.
When straightened, these trees will require bracing for a long time. Larger trees and shrubs will almost always be weakened.
Before you reset a tree, cut, smooth and paint all jagged and irregular root breaks. After resetting, water the tree well and keep it watered during dry periods. Do not remove guy wires or braces for at least 2 years.
Prune a damaged tree just enough to balance root losses. Cut out broken, diseased and malformed branches to give the tree a desirable shape. Fertilization may help induce good growth.
If the crown of the tree needs strengthening, use cables between the weakened branches:
- Insert tag bolts from one-half to one-third of the way between the base and the tip of the branches you want to brace.
- Attach the cable ends to the bolts and tighten the nuts to draw the cable taut. A block and tackle will make the job easier.
- Avoid using short lengths of cable low in the tree.
Exposed roots should be covered. Use nearby sand and silt deposits if there are any. It is not essential to use regular soil to cover roots. Build the root cover to its approximate level before the flood. Do not build it higher.
After repairing trees, continue to care for them:
- Remove silt and sand deposits. Prevent further damage to root systems by removing all deposits to soil level before the flood.
- Check soil moisture. The variety and species of trees and the soil's natural ability to retain or expel excess moisture will determine what actions are necessary to avoid losses due to excess moisture.
- Mulching is safer than fertilizing for damaged trees.