Our Texas landscape has suffered greatly from the drought. Many trees, particularly in nonirrigated areas, have dropped leaves or the leaves are brown. Are these trees dead or alive?
Trees will drop leaves in order to stop transpiration, the loss of water from the leaves. Transpiration is a natural process that draws water from the soil into the roots, through the plants and out through openings in the leaves called stomata. Transpiration increases when the temperature rises, humidity drops and the wind blows. There is a correlation between water loss due to transpiration and water absorbed from the soil. When there is not enough water in the soil, plants try to slow the loss of water from the leaves by closing the stomata opening. If water loss continues to exceed absorption, trees drop leaves. If lack of soil moisture continues, roots die, branches die and trees die.
While some of our trees are dead, some are merely dormant. To diagnose a tree, scrape a small amount of bark on small stems. Green tissue is under the bark on live stems and the wood is white. Live wood will bend when you try to break a stem; dead stems will snap. The small twigs may be dead but the large branches may be alive. If you have doubts, consult an arborist or wait until spring to see if the tree grows new leaves.
Unfortunately, large dead limbs can snap just like small limbs. If a drought-damaged or dead tree is near a structure or may endanger people or property, consider removing the dead branches or tree. If a large dead tree has lost roots, the entire tree may fall during a wind storm.
Newly planted trees or young natural trees are more susceptible to drought damage than established trees. Add a 2- to 4-inch mulch layer around a newly planted tree about a foot beyond the drip line. Mulch slows evaporation of water from the soil so the roots have water available for a longer time.
Dotty Woodson is the water resources specialist at the Texas AgriLife Extension Service. Reach her at 972-231-5362 or firstname.lastname@example.org.
Source: Star Telegram