The Minnesota Department of Natural Resources (DNR) says that knowing which trees to save and which to remove after a windstorm can impact people's safety and the survival of their remaining trees.
Information and advice on tree care, proper pruning techniques, overall tree health, and considerations for removing a damaged tree are available on the DNR website at www.dnr.state.mn.us/treecare/maintenance/stormdamage-prevention.html.
DNR Forest Health Specialist, Mike Albers, offers the following tips.
• Carefully inspect standing trees for damage; deal with hazardous trees first.
Seek professional help, if available, when deciding which trees to remove. If more than 50 percent of the trunk circumference or live branches in the tree crown are damaged, or the tree is leaning with evidence of root lifting or breakage, the tree should be removed.
• Watch for detached branches, loosely hanging branches, and split or cracked trunks that could cause injury or further damage.
• Use proper pruning techniques, but limit pruning to making the tree safe. Incorrect or overpruning will further damage a tree that is under stress.
• Be careful not to overwater damaged or water-stressed trees – especially in heavy clay soils. In dry conditions, trees need one-half to 1 inch of water per week during the growing season.
• Use mulch to help conserve water in the soil, keep the soil cool, prevent soil compaction, and encourage more root growth. Keep mulch at least 4 inches away from the tree's trunk, maintain a depth of 2 to 4 inches deep, and cover an area at least 2 to 3 feet in diameter around small trees. Increase the diameter for larger trees.
• Don't try to save or repair a broken branch or fork of a tree with tape, wire, bolts, or other wraps. It will not heal and the split will invite decay and further weaken the tree. Cabling or bracing should only be performed by a certified arborist and inspected annually.
• Don't top trees - doing so removes large portions of leaves needed for food production, makes tree more susceptible to insects and disease, and may result in new branches that are weakly attached.
• Don't try to save a leaning tree that is more than 15 feet tall, especially if the soil has been raised on the side opposite of the lean. This usually indicates broken roots. Very young trees less than 15 feet tall may survive if they are gently pulled back into place. Be sure to press out air spaces in the loosened soil. Also water the entire root system twice each week in the absence of rain, mulch the tree, and carefully stake the tree for the first year. Tree staking is not usually recommended when planting new trees, but is of value for a tree that has been bent of blown over.
• To avoid damaging the trunk, don't use rope, or any narrow band of material when staking a tree. Instead, use a broad strap or other fabric at least one inch wide. Date the staking and remember to remove it next year.
• Don't panic and remove all living, healthy trees. Consider the value of these trees for aesthetics, property values and cooling shade.
• Don't be rushed by "bargains" offered by inexperienced vendors. Improper pruning (or tree removal) can be expensive and damaging, and sometimes result in the removal of healthy trees.
• Don't allow the use of climbing spikes on a tree that will be saved.
• Don't fertilize damaged trees. The tree's root system may not be able to support the extra growth.
• Don't use paint or wound dressing to cover wounds as these materials may actually interfere with the natural wound-sealing process. An exception is using latex-based paint to seal the wounds on oak trees during the months of May, June and July in areas that experience oak wilt.
More extensive information on the proper care of trees can be obtained from local DNR or county extension offices.