Tree health has been one of the major issues occurring throughout our region. Although, since the end of July, our rainfall is 0.8” above average for the year. That is deceiving due to the fact we had some larger than normal rain events prior to the impending drought. So, while driving around, you may see a dead tree here and there that was not showing symptoms in previous months or weeks.
Besides being struck by lightning or having previous freeze damage, environmental extremes play a major role in the overall health and longevity of trees. Droughts and floods/rainy years can have both long- and short-term effects on trees. In many cases, trees can exhibit symptoms years or sometimes decades later.
This year, as the drought continues, we are seeing trees and plants begin to suffer. Symptoms have been described as a rapid appearance of chlorotic (yellow) and/or necrotic (brown and dead) leaves throughout the entire crown.
The leaves often remain attached on the twigs, but the trees are dead. Alternatively, another scenario that occurs is the leaves drop off leaving a tree with sparse foliage and thin canopies. These trees are lingering with various stages of twig and branch die back but are still alive. Many times trees need to be evaluated by someone to determine what the symptoms are telling us and what can be done to resolve the issue. Many times, there is nothing we can do. Sometimes we just have to wait and see how the tree will respond.
An example of one type of tree that has been majorly affected are post oaks. The Plant Disease and Diagnostic Lab in College Station has determined the rapid decline of the post oaks is a result of many adverse environmental conditions. Post oaks do not tolerate “wet feet”!! Simply, trees get stressed and are often unable to defend themselves. The extremes of soil moisture (drought and/or drowning) lead to root rots, cankers, and wood boring insects.
Root rot can develop as a result of saturated soils (poor internal soil drainage) resulting in inadequate oxygen to the trees’ root system. The symptoms can be browning leaf edges, leaf yellowing, limb dieback and possibly tree death when conditions occur over long periods. Trees under these conditions are more susceptible to diseases, fungi and even wood boring insects. Root systems are used to anchor the tree. In high saturation scenarios, trees can have the potential to uproot and fall over.
Extreme drought causes trees to cope with stress by expending the stored carbohydrates they normally depend on to grow, reproduce and defend themselves against pests and diseases.
During years of normal temperatures and rainfall, these storage carbohydrates accumulate in the roots as a result of photosynthesis. Symptoms are the same as above and can include the wilting of leaves. Often, trees can become brittle and branches can be compromised. This can typically be seen as individual (smaller) branches dying in the canopy.
So, what do you do if a tree is dead? Well, it depends on where the tree is. If the tree falls or limbs break, will it impact the house, cars, people or other property? If it will, then do not hesitate to have the tree removed or at least remove dead limbs or branches. We certainly do not want damage to occur to you or your property. Just remember when hiring someone to trim or remove trees:
• Ask for proof of insurance and then phone the insurance company if you are not satisfied. A reputable arborist carries personal and property damage insurance as well as workers compensation insurance.
• Ask for references to find out where the company has done work similar to the work you are requesting.
• Get more than one estimate, unless you know and are comfortable with the arborist.
• Get it in writing. Most reputable arborists have their clients sign a contract. Be sure to read the contract carefully.
During stressful years, trees respond and survive by mobilizing and depleting stored reserves. Environmental extremes add up over the years. Each tree will show symptoms at different times. So, when you start seeing symptoms, just keep in mind the history of the tree. How many catastrophic events has that tree seen over the last 10, 20 or 50 years? Just in the past 15 years we have experienced the drought of 2011 and record rainfall caused by hurricane Harvey in 2017, the major freeze event of 2021 and now the drought from last summer and now the current drought.
Our trees have been negatively impacted by previous events. They will continue to show symptoms now and in the future. Do what you can to provide additional deep moisture to trees. Just keep in mind that some areas of our county and region are moving into different drought stages and may have certain watering restrictions in place.
Don’t forget to send your garden questions to Plant Answers at 9020 Airport Rd., Conroe TX 77303 or e-mail me at mpotter@ag.tamu.edu.
