Drought stress causing some Texas trees to enter dormancy early

As summer comes to an end, some Texas trees may appear to be showing fall color ahead of schedule.

Prolonged drought and extreme heat can cause hardwood trees, particularly oaks, to develop brown or yellowing leaves and fall-like coloration earlier than expected. Across East and Central Texas, these changes may be a sign that trees are entering premature dormancy in response to severe drought stress.

While premature dormancy can be a survival mechanism that helps trees conserve resources until conditions improve, drought can also cause leaf scorch, dieback and other damage that may appear similar. It can be difficult to determine from appearance alone whether a tree has entered premature dormancy or is experiencing more severe drought-related damage.

Trees lose water through transpiration, the process of releasing water vapor through their leaves. By slowing physiological processes and shedding leaves, drought-stressed trees can significantly reduce water loss and protect critical vascular tissues in the trunk and branches.

Trees may enter premature dormancy gradually, showing symptoms such as leaf wilting, yellowing, marginal leaf scorch and eventual leaf drop. Other trees may respond rapidly, with an entire crown turning brown within only a few days.

Close-up of broad green tree leaves showing early dormancy, with brown, dried edges and patches of discoloration on several leaves. Sandy ground is visible in the background.

Mature East Texas tree in early dormancy, with much of the canopy turning brown while some green leaves remain. The tree stands against a cloudy sky with surrounding woodland in the background.

While premature dormancy can help a tree survive periods of environmental stress, it does not guarantee survival. Some trees may ultimately die during prolonged drought, and drought is often only one of several stressors contributing to tree mortality.

Determining whether a tree is dormant or declining/dead can be difficult through visual inspection alone. One way to assess a tree is to examine small twigs and fine branches. If they remain flexible and bend without snapping, moisture is likely still present within the living tissue, suggesting the tree is alive but dormant. Branches that are brittle and break easily may indicate mortality or severe dieback and warrant further inspection.

Another method is to gently scratch a small section of bark on the trunk or branches. Green, moist tissue beneath the bark indicates the tree is still alive. If the tissue is brown and dry in multiple locations, the tree may be dying or already dead.

Trees experiencing drought stress should not be expected to immediately “green up” following supplemental watering. Leaves that have already yellowed, browned or developed leaf scorch will not return to a healthy green color and trees that have shed most or all their leaves should not be expected to produce new foliage. Significant and sustained improvements in soil moisture and weather conditions are needed for trees to recover from prolonged drought stress.

In some cases, it may not be possible to determine whether a tree survived prolonged drought until the following spring, when surviving trees should resume normal growth and produce new leaves.

Supplemental watering can help reduce additional stress on trees and protect the fine feeder roots responsible for much of their water uptake. Maintaining adequate soil moisture can help prevent these roots from dying and allow trees to recover more efficiently when rainfall returns.

Recently planted trees should receive consistent watering. During normal summer conditions, young trees can receive 2 to 3 gallons of water per inch of trunk diameter 2 to 3 times per week, provided the soil remains well-drained and is not saturated.

During drought conditions and water restrictions, the goal shifts from promoting growth, to keeping trees alive until conditions improve. In extreme drought, trees can often survive on 1 to 2 gallons of water per inch of trunk diameter once per week.

Avoid excessive watering, particularly around mature trees that are generally better adapted to periodic drought conditions than recently planted trees.

When caring for drought-stressed trees:

Water during the early morning or evening to reduce evaporation.

Use drip systems, bubblers or hoses instead of overhead sprinklers when possible.

Maintain 2 to 3 inches of mulch over the root zone, keeping mulch away from direct contact with the trunk.

Avoid applying chemical fertilizers during drought stress.

Avoid unnecessary pruning of live branches.

Minimize soil disturbance and compaction beneath the tree canopy.

Avoid digging holes around trees to water more deeply, as this can further dry the root zone.

Inspect irrigation systems for leaks and reuse household water where appropriate.

Continue monitoring drought-stressed trees as environmental conditions improve. If a tree shows no signs of recovery once conditions improve, contact your local Texas A&M Forest Service office for further evaluation.

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