By Jeff Floyd
Certified horticulturist and arborist
As of the end of April 2022, practically no significant rainfall has visited West Texas. Each promise of precipitation is met with frustration. Drought is a constant threat to the most valuable plants in our landscapes, trees. However, there are things you can do now to give your trees a better chance of surviving.
Trees respond to severe drought by modifying their cells to retain more water for longer periods of time. Drought-stressed trees will develop fewer and smaller leaves, or they will shed leaves to avoid water loss. While treetops tend to stop growing during extended dry periods, their root systems will continue to expand wider and deeper.
Unfortunately, as dry periods lengthen, trees become unable to adapt. Without enough water, cells rupture, biological processes stop, and trees die. A drought-stressed tree is easily identified by dying branch tips in the highest part of the canopy first. Smaller leaves and fall-like color are also early indicators of drought stress.
Although the current dry spell is not yet severe, it does deserve our attention. While we are in these early stages, we should be providing trees with supplemental irrigation. A general rule of thumb is to apply at least 10 gallons of water once every three weeks for each diameter inch of trunk measured four feet off the ground. In other words, a ten-inch tree requires at least 100 gallons of water every twenty-one days. The water should be applied in a wide area under the outer tips of the branches (this area is known as the dripline).
Other preservation activities during a drought include a reduction in the amount of nitrogen fertilizers applied near trees, improving soil characteristics with compost teas, additions of potassium phosphite, and applications of tree growth regulators.
Growth regulators slow down the demand for resources by reducing the surface area of leaves and increasing the thickness of their naturally occurring waxy coat. Unfortunately, a major drawback of relying on growth regulators is that they will not become fully effective until next season. Nevertheless, growth regulators will slow down a tree for two or three years after being applied which is often enough to help them recover from drought-related stress.
Start treating your trees today as if they are already experiencing a water deficit. It just may be enough to get them through the heat and drought we are currently experiencing.
