Help Trees Survive Drought

By CARLOS F. VALDEZ
County Program Director
Los Alamos Cooperative Extension Service

Now that we are in the midst of severe drought we should take some special steps to minimize the effect on our trees and shrubs.

  • Recognize Drought Symptoms – Don’t Overreact

Drought will manifest itself differently in different plants. In some foliage will appear wilted. Others exhibit leaf yellowing and defoliation. Many conifers will exhibit brown needles. Homeowners may mistake these symptoms as death; regrettably, plants may be unnecessarily removed. Check for live cambial tissue as evidenced by green tissue beneath the bark.

  • Fertilization NOT

One of the first reactions that many individuals have when plants are under stress is that the plants should be fertilized. Many fertilizers contain high salt indexes and this salt can exacerbate drought problems on plants. In fact, lawns and ornamentals which are scheduled to receive fertilizer applications should not receive any such treatments unless they are receiving sufficient moisture through irrigation.

  • Prioritize the Irrigation

Because lawns receive irrigation, people mistakenly believe they are also irrigating their trees and shrubs. Often, trees and shrubs, especially during drought periods, are not receiving enough water from lawn sprinklers. Established trees and shrubs will generally survive periods of drought, but they may become more susceptible to secondary problems such as borers and bark beetles. Trees and shrubs generally require “deep root” watering, which implies getting the moisture in the root zone down to about 18 inches. How long and how much water is dependent on soil texture. One way to determine this is to apply water using which ever irrigation method for approximately 20 minutes. Then the following day probe the soil to see how far down the water actually percolated. If after 20 minutes there was penetration down to six inches, then you know you will have to triple the time to get the water to a beneficial depth. New transplants should receive irrigation priority over well-established plants. Conversely, occasional irrigation of a large, irreplaceable, valuable tree or shrub should also be considered.

  • Thin Dense Stands

Without periodic disturbance, like fire, Ponderosa pine forests can grow dense, become stressed due to competition for resources, and become unhealthy. This is a good time to consider reducing the number of trees on our properties.

  • Mulch Helps!

Mulch can help retain soil moisture in the root zones of trees and shrubs, and is particularly beneficial to new transplants. Apply mulch to a generous area over the roots around the stem/trunk of the plant to a depth of three inches.

For more information, contact the Los Alamos Cooperative Extension Service at 505.662.2656 or valdez@nmsu.edu.

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