By Emmy Ulmschneider
Master Gardener
Although we have had a large amount of rain and our hot weather may be over, now is the time to understand how the drought of 2023 and our recent hot weather have impacted our urban forest, the trees in our yards. I see the impact of the drought every day when I walk through my neighborhood and see the increase in the number of dead trees and the visible signs that a tree is under stress.
So, what are the signs of tree stress and how do you properly help your trees withstand our extreme hot weather conditions? Most of us inherit the trees in our yards from the previous owner and most are not native to our area so are not adapted to our growing conditions and alkaline soils. In time of stress, we need to provide the best possible care. First, two things to remember:
Although trees of the same variety and may look alike, they are not genetically the same. These genetic differences may govern how the tree responds to adverse conditions. And this explains how two specimens of the same variety, growing in the same yard under the same conditions, may be responding differently to the hot weather.
The effects of heat and drought are cumulative. The longer the drought and high temperature goes on, the longer the tree will be exposed to adverse conditions. That could also include winter freeze damage which can affect summer growth.
Start by observing your trees. Even now after our recent rains, the structural damage from drought is visible. The trees in your yard are dependent on the amount of water you give them and how it is delivered. Soil moisture, whether for trees, turf, or vegetables, is a limiting factor to growth so you want to water properly.
Where you put the water matters. A trees roots are in the top 3” to 6” of soil and extend out from the dripline, an imaginary ground ring defined by the tree canopy, for quite a distance. The dripline defines the area that receives most of the rainwater dripping from the tree. Watering beyond the dripline means that you will be watering where the tree roots can make the best use of our precious water. Water long enough to get water to the depth of the roots. The entire root zone, including three feet beyond the dripline, needs to receive deep moisture regardless of the irrigation system used. Soaker hoses and drip irrigation are your best options for watering. For trees planted in lawns, do not rely on turf sprinklers to water both the grass and trees. If you really want to conserve water under a tree, mulch from just beyond the trunk to the dripline.
Look at the leaves. The number of leaves on a tree governs the amount of water used. Trees have several strategies to limit water loss through the leaves. When leaves curl up or ‘cup’ at the tips and the margins, the plant is trying to retain moisture by closing its stomata, which in turn affects photosynthesis, the plant’s food making process. Drought stressed trees die from the top down, so look at the top of your trees. Do you see fewer leaves or dead leaves at the top? Do you notice an excessive number of dead leaves on the ground around your tree? If you do that is a sign that your tree is shedding leaves to conserve water. You may need to change your watering practices.
If you have questions, call the AgriLife office in Odessa at 498-4071 or in Midland at 686-4700. Additional information, and our blog for access to past articles, is available at westtexasgardening.org. Click on “Resources.”
