Mulch around your trees with 2 to 4 inches of organic mulch to reduce moisture loss. Use wood chips, shredded bark, leaves or evergreen needles as mulch. While many homeowners prefer to have grass growing under their trees, maintaining mulch within the drip line of the tree is better for the tree and is more representative of its natural environment, the woods. Avoid the use of stone or rock near trees as this increases air temperatures and moisture loss from leaves and stems. Keep mulch 6 inches from the trunk of the tree.
Do not fertilize a tree that is under drought stress. Salts in fertilizer may burn roots when there is not sufficient water. Fertilizers may also stimulate top growth resulting in too much leaf area on the plant for the root system to maintain during periods of limited soil moisture. If fertilizer is needed and soil moisture is adequate, fertilize after the grass goes dormant.
Properly prune trees and shrubs during time of drought to improve structure, limb stability and to remove dead and weakened branches. Leaving broken, dead, insect-infested or diseased branches can further weaken a tree during drought and set the tree up for deadly secondary insect and disease problems.
Many tree species are harmed by herbicides used in the lawn. Trees already stressed by drought can be harmed by a heavy application of herbicide in the root zone. Avoid using herbicides during stressful times or only do spot treatments if possible. Be sure to always read and follow label directions.
Following these guidelines will help preserve our trees, the most valuable assets to our landscapes.
Ray Ridlen is an agriculture/horticulture educator for the Oklahoma County Extension Service. For more information, call 713-1125.