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- 29. Drought Leaves Trees In Need of Water - Top
- Drought Leaves Trees In Need of Water
It was just one year ago when we were in the midst of one of the driest winter seasons on record here in Tucson. But this winter has proven to be even drier! This means that plants, especially large and medium-sized trees are beginning to suffer from a lack of moisture. Injury is not apparent now, but will soon be if water is not provided. If you have trees that are not currently being watered, now it the time to do so.
Pine, eucalyptus, oak, sycamore, and cottonwood are most urgently in need for water. Large desert trees, such as mesquite, palo verde and acacia are also being stressed by the lack of rainfall . The larger the tree, the more critical the water need. However, even moderately-sized trees should be watered during our current drought.
For now, one good soaking is all that is necessary.A "good soaking" means a long, slow wetting of the soil around the roots. Most drip systems do a poor job of watering trees. This is because tree roots extend out well beyond the ends of the branches. The typical drip system only has one or two drippers at the base of the tree. A good soaking must include all the ground between the tree trunk and the branch ends. Watering out farther is even better.
A soaker hose is most effective in providing a good soaking. Coil the hose around the tree, beginning two or three feet from the trunk. Spiral the hose out maintaining a two foot spacing between the circling hose as you go. Extend the circle all the way out to the edge of the edge of the branches. If you can't cover the entire area to be watered at one time, then water the tree roots in quarter sections. When your done with one section of the roots, then move the hose and begin watering another. Water should be applied until the top two feet of soil is moistened. This can take many hours.
Periodically check when applying water to see how deep the moisture has penetrated. To do this, use a metal rod, such as a two foot long re-bar which can be purchased at hardware or building supply stores. When the soil is moistened, the rod can be pushed in to the depth of wetting. Try pushing the rod down in several locations. Because of rocks and other soil debris, the probe may strike one of these objects and give you a false reading. Try another spot.
An alternative to using a soaker hose is to flood irrigate, using the basin method. Build a small berm of soil, three or four inches high, around the tree a few feet beyond the branch ends. This circular berm will serve as a dam, holding the water in until it is absorbed into the soil. Rapidly fill the basin with water and allow it to soak in. Repeat this process until the soil has been moistened down two feet.
If our current drought continues, trees should again be watered in May. Of course, if the weather remains unusually warm, then waterings a second time may be needed even sooner. Remember, these recommendations are for trees that are not being regularly irrigated. It also applies to medium and large trees that are not being thoroughly watered by drip irrigation. Less than 10 emitters on such trees means you better hand water using the previously stated methods.
Trees are the most important component of our urban environment, especially here in the desert. They provide cooling shade, oxygen to breath, filtration of air pollutants, wind buffering, soil improvement and beauty. They're also your most important and valuable home landscape asset. Keep that in mind when making a decision about what to water. Vegetables, flowers, ground covers and shrubs can be replaced at minimal cost. They also grow quickly. Not the case with trees!
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Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona, 520-626-5161.
Material originally appeared in Arizona Daily Star gardening column, on February 20, 2000
- Updated: February 20, 2000
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