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Rain has greatly helped drought-stricken trees, but not all out of the woods yet
By Kathy Huber | July 27, 2012
Tree stewards breathed a collective sigh of relief after abundant rains eased the historic 2011 drought. But while the need to water them has dropped, many trees are not yet out of danger, Mickey Merritt of the Texas Forest Service says.
"The trees in the Houston region have been under tremendous stress for some time now, and last year's heat and drought were devastating to our urban forest," he says. "While the much-needed rain is allowing the trees to start to recover, they still have a long road of recovery ahead of them. We could still see mortality from the drought for a couple of more years."
Merritt says various problems are now affecting hardwoods, including hypoxylon canker, a fungal disease, and increased borer activity. Both hypoxylon and borers generally attack stressed trees.
Branch die-back is an obvious symptom of hypoxylon. Foliage on diseased limbs turns yellow and dries. The disease spreads from branch to branch until the tree dies; the process may take one or more years. In the late stages of the disease, bark will slough to reveal powdery spores.
The only way to control hypoxylon is maintaining tree health and preventing bark wounds and root injury, which are especially prevalent in construction zones.
Stressed pines are susceptible to Ips bark beetles, Merritt says.
The best thing home-owners can do now is to make sure their trees get sufficient water during hot dry weather, he says. Water slowly so moisture penetrates the soil to a depth of 6 to 8 inches. Information on watering trees can be found at txforestservice.tamu.edu.