Tips for saving trees

Even though the triple-digit temperatures have dipped into the double digits, and there is a slight chance of rain in the forecast, Don Smith, associate professor of biological sciences, says the area's trees are still at risk of dying.

"Not even the horrid summer of 1980 was so hard on trees," says Smith. "This severe heat and dryness imposes severe stress on plants. It is critical to help our trees through this heat because they require so long to replace if they die."

Post oaks are the predominant species in the area. Any nearby construction places them in jeopardy, and with the area's constant growth, a large number of post oaks are threatened every day. But even post oaks that have not been encroached upon are in dire stress now, Smith says. Many of them will die if they do not get supplemental water.

Other trees that are especially vulnerable now are sweet gum, magnolia, and pines.

To determine if a tree is severely stressed, Smith says to examine it early in the morning. If the tree is still wilted after sitting overnight, it needs help or it will die in a few days.

Smith and Denton County Horticultural Agent John Cooper offer the following directions for adequately watering trees.

The most efficient use of water in conditions like this is to water with a soaker hose at night.

When watering trees, remember that the roots extend in all directions as far from the trunk as the tree is tall, and it is important to irrigate the entire potential rooting area. However, watering the drip line (the periphery of the canopy of the tree) is probably the most effective area to concentrate on if water is limited.

Put out one inch of water, once a week in the absence of rain for turf. For trees, double the application (2 inches) every second week. Where you have only trees, if money is no object, water 2 inches every 10 days. Where money is an object, water 2 inches every second week.

This may take several hours of slow watering, but trees require dozens to hundreds of years to replace, so they are worth extra effort to preserve, Smith says.

Because it is important to conserve water, the soil should be allowed to dry between watering.

"When you stick your finger in the soil, you shouldn't feel any moisture," Smith says.

Homeowners who have sprinkler systems should set their sprinklers to operate during the night, and double the application of water every two weeks to ensure proper saturation for trees.

However often you water, you need to water the same area each time. Skipping around does no good, as roots are opportunistic and reviving roots one week only to dry them out the next is not helpful. Revive the roots and keep them active by watering the same area time after time.

Homeowners also should remember to water their foundations as well as their trees and yard. When the soil dries out, the earth shrinks and the slab may shift, causing the foundation to crack.

And, if the drought continues and the need to conserve water becomes stronger, people will need to begin to make some choices about where they use their water.

"A lawn can grow back in a year," he says. "Trees can take a hundred years or more to replace. And a cracked foundation is extremely costly to repair."

BY KELLEY REESE kreese@unt.edu

Other featured articles in this issue

• Norval Pohl recommended for UNT presidency
• Chancellor and President Hurley marks 20 years of service
• Faculty receive awards at annual ceremony
• Enrollment opens for early childhood music classes
• College of Music responds to string teacher shortage
• Five Brewer students to enter TAMS
• Clinic to hold group sessions

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