Are your trees suffering from drought stress?

The summer of 2024 had a scarcity of rainfall, resulting in a drought period of approximately 3 months. All of Ohio (87.7%) experienced drought conditions by September, and some parts of the state (35.8%) experienced extreme to exceptional drought (independenttree.com). This lack of rainfall caused significant stresses for Ohio's trees, and the symptoms of these stresses do not show up right away. Trees need adequate water entering the growing season, to produce leaves and fruit, and complete photosynthesis. Lack of water can cause the tree to divert energy from growing to basic survival. Younger trees less than 3 years old are affected first, due to underdeveloped root systems. The leaves lose more water than the roots can supply. Browning of leaf edges occurs, as well as browning between the veins in the leaf. If dryness continues, the colors may turn early, and leaves may wilt and fall off in large numbers. Evergreen trees (conifers) may seem to turn brown suddenly, and die. Trees planted in compacted soil are at risk due to lack of moisture retention. Older, well-established trees may take longer to show drought damage, sometimes dying within 3 years. The tree continues to deplete its reserves and is susceptible to insects and disease (extension.illinois.edu). Large trees stressed by extreme drought continue to decline despite their larger root systems. Arborists can treat some trees with a growth regulator which slows growth and focuses the trees energy to its reserves, however, it is expensive and long-term success is not proven. The stress period most drought-resistant trees can handle is a few weeks. However, the 2024 drought lasted 3-4 months, and likely caused long-term damage for many Ohio trees. This summer also experienced drought, potentially compromising trees even more. If there has been no rain for 3 weeks, consider watering once a week until rain returns. Deeply watering the root system (with a soaker hose) is better than short, shallow waterings. The suggested guideline for watering is 10 gallons water for every inch of trunk diameter, weekly, inside the dripline of the canopy. Signs of drought stress include: light green to yellow green foliage, stunted new growth, leaf scorch, smaller leaf size, crown thinning, early leaf coloring, leaf drop during summer, vertical cracks in the bark, and increased seed production. Trees with high water needs, such as oak, maple, birch, beech, and dogwood, often do not have drought stress symptoms until 6-12 months later. If you notice serious signs of drought stress, such as large branches dying or many branches dying throughout the tree canopy, splitting bark, or the tree visibly leaning, it would be smart to consult a certified arborist. A compromised tree should be removed if over 50% of the canopy is dead, cracks in the trunk or root damage is significant, or the tree is leaning and posing a risk to people, structures, or traffic. Record the current condition of trees for insurance reference (document and take pictures). When a tree dies, choose a replacement that is drought resistant, and has plenty of room to grow. For more information on dealing with drought, go to https://extension.illinois.edu/blogs/good-growing/2023-09-15-early-fall-color-could-be-sign-tree-stress There are things you can do to support a drought-stressed tree: water deeply and slowly once a week, improve the soil with applications of compost, apply a 2-4 inch layer of mulch out to the dripline (avoid mulching right up to the trunk), and frequently monitor the condition of the tree. Taking care of the health of our trees will help them survive dry spells and provide us with shade and beauty for many years to come!