Healthy trees are often capable of combating mild insect attacks. In fact, many of the telephone calls we receive are about insects that normally only attack dead and dying trees and are not the cause of the tree's problem. What can you do for a tree to keep it healthy? Here is a short list.
1. Make sure the tree receives the appropriate amount of sunlight for the species.
2. In my opinion, trees (especially established trees) need zero or little added fertilizer. Extra nitrogen can cause overgrowth or might encourage certain insects.
3. Perform a soil test to see if soil conditions are appropriate for the tree.
4. Minimize turf around the root zone. Use mulch if possible, but NOT against the bark. Apply mulch three inches deep at the most. Turf and tree roots are in direct competition for water. Regular lawn fertilization is not beneficial to the tree.
5. In order to reduce soil compaction, avoid parking vehicles, having playgrounds or conducting other heavy traffic activities beneath a tree.
6. Don't change the oil from the old 1960 Ford Galaxy (that you've been restoring to look like the police car from The Andy Griffith Show) under the tree.
7. Quickly prune out any newly damaged limbs. Tree injuries can attract insects within hours.
8. Drought conditions may not have a noticeable impact on established trees the first year. Repeated dry conditions may result in a problem two or three seasons later. If possible, practical and affordable, watering a specimen tree might be justifiable. Ask about the best way to do this if you are unsure.
9. Keep that mower and weed trimmer away from the bark.
From Dr. Steve Bambara, NCSU Entomologist
For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.
