Residents of North Texas are familiar with long, hot summers that take a toll on everyone and everything. From drinking extra water, keeping our pets cool, and making sure our air conditioners are working, summer in DFW can be a busy time. While watering our lawns is common practice, many homeowners do not think about the water needs of their trees. During a Texas summer, and especially when we are in drought conditions, providing adequate tree care is critical to helping your trees survive and thrive.

How Does Drought Affect Trees?

Trees are able to store water and nutrients and so may not show signs of drought stress immediately, at least not to a casual observer. When trees are greatly affected by lack of water, these symptoms are common:

• Yellowing, wilting and browning leaves
  • Leaves turning colors other than green (except in species that exhibit other colors of foliage) is often the first sign that something is wrong with a tree
• Leaf drop/defoliation
  • Keep in mind that some species (like live oaks and magnolias) exchange leaves throughout the year, rather than all in the fall, so some leaf drop is natural
• Dieback at the end of branches and limbs
  • As a tree loses vitality, the smaller growth is often the first to die
• Sunburn
  • As the canopy loses leaves, larger parts of the tree become exposed to sunlight
  • Constant exposure to light and heat causes damage to the outer layers of bark, which can start to die and fall off, exposing the nutrient-carrying parts of the tree to more heat and sun

Even when visible signs are not present, trees experience stress soon after their needs for water are not met. Some of the “invisible” signs of drought stress are:

• Death of fine, nutrient-absorbing roots
  • In addition to the large stabilizing roots, trees have fine, hair-like root structures in the top layers of soil that absorb water and nutrients
  • These roots die quickly when the soil around them becomes dry and hot
  • As these roos die, the tree loses its ability to take up moisture and nutrients from the soil, leading to further stress and dieback
• Reduced ability to fight off diseases and pests
  • If a tree is losing energy due to a lack of incoming moisture and nutrients, its defenses are less able to resist other attacks and stressors
  • If bark is being lost, pests that feed on the heartwood have easier access
• Stressors that are normally insignificant can become big issues
  • The impacts of unnecessary removal of green wood, damage to the canopy or root system, and stress from nearby activity (such as construction) are amplified by drought stress

What Can I Do to Help My Trees in a Drought?

Water. Water. Water!

The most important thing to do to help your trees is water them.

• A lawn sprinkler system is NOT enough to keep trees hydrated.
  • Trees need much more water than turf grass or smaller plants, and must be watered correctly, if there is to be any effect.
• North Texas Tree Watering Guide

Use Mulch to Regulate Soil Temperature and Moisture

Proper use of mulch around trees reduces the amount of watering needed and provides vital nutrients to the soil and tree roots underneath.

• How to Use Mulch

What to Avoid in a Drought (and Always!)

DO NOT Use High-Nitrogen Fertilizer

• Nitrogen stimulates rapid growth, which expends a tree’s depleted energy stores quickly

DO NOT Use “Weed and Feed” Products

• The “weed” component is a tree-targeting herbicide, and the “feed” is often a nitrogen-based growth stimulant

DO NOT Over Trim Trees

• Avoid unnecessary trimming and removing too much of the canopy, which reduces a tree’s ability to draw up moisture and exposes the branches to the sun

DO NOT Disturb the Area Under a Tree’s Canopy (Critical Root Zone)

• Digging, trenching, planting, construction, and other activity can destroy the fine, nutrient-absorbing roots and even damage larger roots, leading to instability

How Arborists Help in a Drought

Whether your tree is showing signs of lack of water, or is withstanding drought stress, proper tree care from an ISA Certified Arborist® is crucial to giving your trees the best chance to survive a drought.

• Proper trimming to remove dead or diseased wood, and provide airflow to keep the canopy cool
• Applying organic soil amendments designed to help drought-stressed trees supplement any lack of nutrients in the environment
• In cases of root damage, pest activity, or heat-related diseases, recommending plant health care programs designed to reduce stress and encourage healthy growth
• Reminding you to water!

Proper summer tree care (especially watering!) is the key to keeping fine root structures alive so that trees are able to get the water and nutrients they need to survive a drought. The top two to four inches of soil around the base of a tree and under the canopy is where a tree gets most of what it needs to grow. Keeping that area stable, watered, and cool goes a long way toward having trees that thrive even in a North Texas summer.

At Texas Tree Surgeons, we love trees and we love our community! The Texas drought in 2011 killed an estimated 300 million trees, including 5.6 million urban shade trees. We are keeping an eye on Texas drought conditions and adjusting our recommendations and practices accordingly. If you are concerned about your trees or have questions about how best to care for them, one of our ISA Certified Arborists® would be glad to talk to you! Contact us today!