Extension

As Oklahomans celebrate the fall season with pumpkin spice everything, homeowners should consider how their landscape trees will fare over the winter. While humans can snuggle under a warm blanket and sip a cup of hot chocolate, landscape trees will benefit from a little TLC.

 

Landscape trees are a long-term investment and add significant value to the property, so proper care is essential. Oklahoma experienced a much wetter spring than usual, but the state tends to have relatively dry winters. Because tree roots continue to grow throughout the winter, they need moisture to survive. Dry, cold soil can be damaging to the root, which can cause issues for overall tree health in the spring.

 

Trees produce two kinds of roots – large perennial roots and small absorbing roots. The large roots are woody, increase in size, grow horizontally and provide anchorage for the tree, water and mineral conduction, food and water storage. The smaller roots are short-lived and grow outward and predominantly upward from the large perennial roots toward the surface, where minerals, water, and oxygen are generally abundant. These roots make up the major portion of the root area. Here’s a fun fact – 90% of a tree’s roots are in the top 12 inches of soil.

 

Deep watering during the winter is essential to keep the tree healthy, but there are other steps to help ensure good tree health.

 

• Mulch around trees with about 2 to 4 inches of organic mulch to prevent moisture loss but keep the mulch at least 6 inches from the tree trunk. Wood chips, shredded bark, leaves or evergreen needs are good options. Avoid using rock or stone near trees because they can increase air temperatures and moisture loss from leaves and stems.
• Don’t fertilize a tree that is under drought stress. The salts in the fertilizer may burn roots without sufficient water. Also, fertilizers may stimulate top growth, resulting in too much leaf area on the plant for the root system to maintain during periods of limited soil moisture.
• Keep trees healthy and pest-free. Detectable pest or disease problems should be treated immediately to reduce the overall stress to the trees.
• Correctly prune trees and shrubs to improve structure, limb stability, and remove dead and weakened branches. Leaving broken, dead, insect-infested or diseased branches can further weaken a tree, especially during the dry winter season, and leave it open to deadly secondary insect and disease problems.
• Be careful when applying herbicides in the landscape. Trees already stressed by low water conditions can be harmed by a heavy herbicide application in the root zone. Homeowners should avoid using herbicides during stressful times or only do spot treatments. Be sure to read and follow label directions.