Summer Heat Stress & Drought:
A killer combo for the landscape
Drought conditions, extreme heat, and abnormally lack of water has become a very oppressing issue to those living in the inter-mountain regions of the southwest United States. This includes all of New Mexico and western Texas regions.
The last two decades have been the worst in 1200 years according to those who study and monitor climatic conditions and events.
As of June 29, 2023, the U.S. Drought Monitor agency released a new status map of New Mexico and Lea County drought status conditions. We have moved from “Extreme drought” status to “Severe drought status. Our readers in West Texas communities are in the same boat with us. The State-line counties of New Mexico/Texas are all in “Severe to Moderate” status.
The drought is predicted and forecasted to be “persistent”, not ending anytime soon. Climate changes are dramatically affecting climatic conditions around the world. Let me inform you of other imminent concerns arising out of this drought.
Current reports monitoring drought in the Agriculture and Ranching industries are extremely affected in Lea County.
➡ 15, 532 acres of cotton
➡ 8,881 acres of hay
➡ 2,406 acres of haylage
➡ 55, 233 head of cattle (estimate)
➡ 2,871 head of sheep (estimate)
➡ 61,397 Lea Countians affected by drought.
➡ 94.9% Lea Countians affected by drought.
➡ 43rd driest year to date over the past 129 years
I could go on and write about more information on drought and crisis conditions in New Mexico. Let me regain my focus, to these conditions affecting and destroying your home landscapes and plantings.
Now, I urge everyone to grasp the grave concern over “water conservation and managing a very precious resource”.
Prioritize your trees and shrubs
Extreme heat is a form of abiotic stress and will negatively impact plant health and efficiency of normal processes such as metabolism and respiration. Flowers and vegetables will wilt and turn yellow, dying. Do not waste your time on short-lived plants. Trees and shrubs are long-lived investments. If your trees and shrubs are established in the home landscape, it shows they have weathered a few summers already. If they are suffering now, it means the weather has pushed them to their limit, or something else has changed in their environment. If trees and large shrubs die back completely, they are not easily replaced, Removal can be difficult and very costly. For this reason, it is important to monitor your woody plants during these periods of intense heat and prolonged drought.
Apply water until the soil is wet to the depth of your plant’s root system. This means letting water soak into the soil 3-feet deep on large trees and at least 2-feet deep on shrubs. Water to 1-foot in depth on smaller plants. Use a water-probe or a piece of rebar rod and push into the wet soil to measure the water infiltration depth. Moist soil, the probe will pass through easily until it hits dry soil.
Water pre-dawn hours before the heat builds up. Change automatic irrigation controllers to come on in pre-dawn hours or even start after midnight. Why so early, Hooten! Glad you all had that question!
Watering with an irrigation system or sprinklers, the pre-dawn watering has the least evaporation, and especially less water loss with wind blowing spray patterns and water loss off-site, street, sidewalk/driveway.
The intense summer heat warms the soil surface rapidly, and the heat begins to dry and wick moisture out of the root zone. Watering early ensures the water applied moves deeper into the soil, where it can be retained and is accessible by plant roots for longer time.
Water requirements for trees are substantial, particularly for large trees. For example, a full-grown pecan tree can use nearly 200 gallons of water on an intense hot, summer day. Over the course of a year, that same pecan tree will use between 3,000 and 6,000 gallons of water. Replacing this amount of water is difficult, costly, and unsustainable from a water resource perspective.
Follow Landscape watering guidelines
The home landscape and gardens account for up to 70% of average residential water consumption. There is never a bad time to make sure that you are delivering water judiciously and effectively to your plants and plantings. With lingering heat and absence of monsoon rains, this is a great time to check out the efficiency of your irrigation systems and scheduling applications times.
There are always exceptions, even in the plant kingdom, some trees and shrubs need more water than other plants. This is true in the case of growing fruit trees with fruit, and nut-bearing trees as these have a high-water need to produce their crops.
Do not ignore plants beyond your irrigation system
You may have trees and shrubs on the edge of your property beyond your irrigated zone. These may be desert adapted natives, or common traditional plants. Consider giving them water by hose to help them through a hot dry summer.
Do not work on your plants.
Do not plant, transplant, prune, trim, shear or deadhead plants during an intense heat wave. ALL such disturbances damage plant tissues and may expose plants to an increase in sun exposure. Do not move plants in pots/containers unless to a shadier site. Do not dig or trench the soil around plants, as this can damage roots. Apply NO chemicals, neither fertilizer, herbicide nor insecticide to plants when they are heat stressed.
Effects of Drought on Trees and Shrubs
During a drought, the amount of water available in the soil declines to a point where the tree or shrub’s roots are not capable of absorbing moisture. While most soils will still retain some moisture, the soil “holds on” to this moisture, making it unavailable to any plants.
If drought conditions persist, the fine hair-like roots, whose primary function is to absorb water, begin to die back. Under prolonged drought, even the larger, fibrous roots are lost. Once root loss has happened, it can take days to weeks for the plants to re-grow the root hairs necessary to take advantage of rainfall or applied water from a hose or irrigation system.
Root loss leads to tree and woody shrub stress and dramatic increased susceptibility to several insects and diseases. Stressed trees attract several types of boring borers, pine bark beetles. There are canker diseases that set into the stressed trees and woody shrubs.
Drought Susceptible Trees
Trees planted in shallow soils will be most definitely a target for drought stress. Trees growing in rocky soils, shallow planters, or compacted soils. These trees will have shallow roots systems and will be subject to hotter and drier surface soils.
Trees adapted to regular short-duration watering will develop shallow roots and be subject to drought if they have NO irrigation.
Signs of Drought Stress in Trees
Signs of drought will be most visible in the foliage of trees. Look for the following symptoms in short-term droughts.
➡ Temporary wilting. Leaves drooping in the heat of day, and then recover at night, by morning.
➡ Permanent wilting. As drought progresses, leaves will remain wilted.
➡ Yellowing leaves. Prior to dropping foliage, leaves will turn yellow.
➡ Leaf scorch. Leaf margins have a brown or burned appearance.
➡ Defoliating trees. Leaf loss from top of trees and tip ends on branches,
➡ Bark cracks. Prolonged drought, trees develop long cracks in the bark.
In long-term droughts, symptoms will appear in a variety of ways.
➡ Dead branches. Branch death in the top or outer tips of the tree.
➡ Thinning foliage. The tree canopy will appear sparse and slightly yellow.
➡ Small leaves. Prolonged drought will cause new leaves to become unusually small.
➡ Slowed growth. Growth will slow and nearly stop.
➡ Increase in insect pests. Wood borers will be active and present.
➡ Become unable to close wounds. Pruning or otherwise
David Hooten also known as Dr.Dirt runs Son Grown,LLC and can be reached at 575-318-8540.