Protecting Your Trees from Heat Stress in Summer

Tree heat stress can significantly impact trees and potentially kill them. Though we can’t control the weather, we have options to limit the impact of heat’s effects on trees. In this article, we’ll look at what heat stress in trees is and how to mitigate it.

What is Heat Stress in Trees?

Heat stress occurs when temperatures rise above the tree’s normal range of tolerance. This can cause the tree to experience a number of negative effects, including leaf loss, reduced growth, and decreased vigor. In extreme cases, heat stress can kill a tree.

There are a number of ways that you can help your trees cope with heat stress.

1. Provide Your Trees Adequate Water

Providing your trees with adequate water is one of the most important things you can do. Deep watering (where the water penetrates deeply into the soil) is best, as it helps to encourage deep root growth.

Ensuring that your tree has adequate water during the summer is essential for preventing heat stress. Water deeply and regularly, paying attention to the tree’s root zone. If possible, try to water in the morning or evening when temperatures are cooler. Avoid overhead watering, as this can promote fungal growth and encourage leaves to droop.

2. Mulch Your Trees

Mulching around the tree’s base can help conserve moisture and keep roots cool.

Mulching is important for tree health all year round, but it can be especially beneficial during the summer months. Mulch helps to keep roots cool and moist, which is essential in preventing heat stress. It also helps to prevent water loss from evaporation, meaning that your tree will require less watering.

There are a variety of different mulches you can use, including wood chips, bark, straw, and compost. Apply a layer of mulch that is at least 3 inches (7.6 cm) deep around the tree’s drip line (the outer edge of the tree’s canopy). Be sure to avoid putting any mulch directly against the tree trunk, as this can cause rot.

3. Tree Pruning in Summer

Avoid pruning trees during periods of heat stress. Pruning can increase the amount of leaf surface area exposed to the sun, which can exacerbate the effects of heat stress. Trees should only be pruned when necessary. Two trees to avoid pruning when it is extremely hot are maples (which can cause health issues) and oaks. Oaks should be pruned in the spring, fall, or winter. Pruning oaks during the heat can attract oak bark beetles, which are carriers of oak wilt disease, often fatal to the tree.

4. Plant the Right Trees

Plant heat-tolerant tree species. Some trees are more tolerant of heat than others. If you live in an area with hot summers, consider planting tree species that are known to be heat-tolerant, such as crape myrtles or live oaks.

If you think that your tree is showing signs of heat stress, contact a certified arborist or tree care professional for further advice. By taking action to prevent and mitigate heat stress, you can help ensure that your trees stay healthy and thrive during the summer months.

What are the signs of heat stress in trees?

The most obvious sign of heat stress in trees is wilting. This happens because the tree is unable to take up enough water from the soil to meet its needs. The leaves will droop, and the tree may lose its leaves entirely. Other signs of heat stress include yellowing or browning leaves, bark splitting, and premature fruit drop.

What are the consequences of heat stress for trees?

Heat stress can cause tree death. In fact, heat is one of the leading causes of tree mortality worldwide. In urban areas, where trees are often planted in confined spaces and exposed to high levels of pollution and heat, tree mortality rates can be as high as 30%. Trees under stress are also more susceptible to pests and diseases. Additionally, heat-stressed trees produce less fruit and seed, which can impact wildlife that rely on those trees for food.

If you think you have found signs of tree stress, it is important to contact a Certified Arborist quickly.