Although the deciduous trees have lost their leaves for the winter and we humans consider the trees to be dormant, physiologically the tree is very active. New roots are being developed and the tree is preparing itself for the upcoming spring. It is important to note that photosynthesis may have stopped when the leaves drop, however, respiration does not. Respiration is the process where food manufactured in the leaves is burned with oxygen obtained through the roots to provide the energy necessary for growth.
What’s the point? The past several winters have been extremely wet with the soil saturated for long periods of time resulting in low oxygen levels in the soil and consequently a low rate of respiration. Many of our tree species which prefer a dry site (Texas Red Oak, Chinquapin Oak, etc.) have experienced some problems related to weakened root systems that I believe to be caused by the excess water and low oxygen levels in the soil.
What can I do? Although no person can control the weather, each of us can control the use of our irrigation system. Our clay soil should be allowed to cycle through wet and dry periods. Prior to irrigation check the soil at a depth of 6 to 8 inches. If it crumbles, it is time to irrigate. If it packs into a wet clay ball suitable for making pottery, no irrigation is necessary. Allowing the soil to dry increases the oxygen content and then the respiration rate. You will have healthier, stronger plants able to withstand our hot Texas summers, if you irrigate less frequently, but thoroughly saturate the root zone when you do irrigate. The benefits are stronger roots, healthier plants and a lower water bill.
The dormant season is an excellent time for tree pruning. Live Oaks and Red Oaks should be pruned at this time or in the heat of summer to cut down on the risk of Oak Wilt disease. Live Oaks and Red Oaks should not be pruned in the spring.
If you have any questions concerning the health of your trees, please call us. One of our Certified Arborists will be happy to answer your questions.by Kevin Bassett - first published in November, 1993