It was remarkable how many times the Tree & Shrub Care Department was called this summer to check on trees that were not looking healthy. Nearly half of all cases, there was one common issue, lack of water.
Symptoms of Stress from Drought
Leaf margins turning brown, leaves wilting or turning brittle are all symptoms of stress from drought. These symptoms can easily be mistaken for tree diseases and insect damage. It is important to recognize the signs of stress induced by lack of water and to not misdiagnose the symptoms to be a fungal disease or insect damage. Sometimes treating an already stressed tree for a fungus or an insect, even treating a tree using a fertilizer, can do more harm than good. Once recognized that the issue is drought, if the damage is not too severe, most of the time it can be quite simple to remedy. It takes a schedule and time. Most customers dealing with drought have been encouraged to water with a hose at the base of the tree three times a week for at least an hour (depending on the size of the tree) until the first snow fall.
The Mature Tree
It is commonly overlooked to water a mature tree during a dry season. The truth is, some trees can take up many gallons of water each day, if it is available. Water evaporates through the leaves, a process known as transpiration. The evaporation of water through the leaves causes a suction in the tree roots that pulls water from the ground. If water is not available, depending on the tree location and soil type the tree may begin to display symptoms of drought.
Tree location is critical to notice when determining if your tree has succumb to drought. If a tree is in an enclosed space, right by a sidewalk and driveway, if it is surrounded by asphalt or if it was planted in a bed of rocks, all these will determine the amount of water a tree has
access to. A sidewalk, road or driveway may not seem significant, when in fact can cause scorch to the trunk and leaves. The sun’s rays are strong, and like rays reflecting off water, they can reflect off the sidewalk or road. Tightly closed quarters, such as in a boulevard, in between the road, and the sidewalk, means limited room for roots to spread out. It also means limited soil space where water can be held. Trees and shrubs surrounded by stones can look serene, however these rocks get heated from the sun’s rays. This increase in temperature can bake the root system of a tree.
Replacing stones with mulch may not seem like the easiest solution, but it is the best remedy for your landscape plants to counteract stress from drought. A thin bed of mulch (1-3 inches) can hold soil moisture, keep the root system from overheating and provides nutrients for the tree as it slowly breaks down.
Soil type can commonly be overlooked when observing symptoms of tree stress from drought. Straight sand (commonly found near the lakeshore) does not have much ability to hold water. The sand particles are so large compared to clay or silt that water moves right through the large particles. If a tree is in sand and it is a dry year, this tree may need regular watering. If a tree is in straight clay, the clay can harden from lack of water. Clay particles are so small (compared to sand), and clay will tightly hold on to water, which is beneficial when there is regular water in the soil. Without regular water, the clay can become solid. Once clay hardens, when it rains or if the tree is watered, the water will stand on the surface of the hardened clay or will just run-off. It takes time and much water for the water to soak into hardened clay and penetrate the surface. The ideal soil type for most landscape plants is a mixture of sand and clay or a silt. Silt can hold moisture and will stay porous if it loses moisture.
Michigan State University Extension reported in 2013, that the drought from 2012 was significantly noticed in maples. Maples experienced early fall coloration as well as chlorotic symptoms, such as yellowing leaves, from lack of nutrients. Summer of 2015 has also been quite dry. Because many of the trees experiencing stress from drought this summer have been maples, and because maples are sensitive to environmental changes, it may be safe to assume these trees may still be stressed from previous drought years.
In most cases, with regular watering trees and shrubs can replenish themselves to be healthy again. It is important to water (especially newly planted trees) in the summertime, especially when there is a shortage of water, if the location of the tree is not ideal or if the soil type is not optimum. A fertilizer can also be beneficial, however, waiting until the tree is healthy again and has plenty of water would be a good time to fertilize. Also, a tree stressed by drought potentially can predispose the tree to other ailments, so watering is all around the best option for your tree.
Wintertime can also prove to be harsh on landscape plants. Constant snow, ice and wind can dry out or burn many plant species, particularly if they experienced drought in the summertime. The Tree and Shrub Care department treats multiple properties in the wintertime with anti-desiccants. Anti-desiccants could aid trees and shrubs from drying out or burning over the wintertime. Watering drought-stressed landscape plants until the snow falls will be most beneficial, and an anti-desiccant could help the struggling tree or shrub stay healthy through the winter, especially if the winter is a brutal one. We use a product called Transfilm for our anti-desiccant treatments. This product creates a coating on the plants that reduces water loss.
If you think your landscape plants may be experiencing stress from drought, call (616) 301-1300 ext 118 to schedule an appointment with one of our certified arborists. They will give you the steps you need to take to get your tree or shrub on the right path as well as the education you will use in years to come with caring for your landscape plants. They can also determine whether or not an anti-desiccant will be beneficial.