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Spokane, Washington  Est. May 19, 1883
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Water Cooler: Evaluating the health of your trees

UPDATED: Thu., July 29, 2021

A healthy tree canopy provides shade and a cooling effect in the surrounding area.  (Pixabay)
A healthy tree canopy provides shade and a cooling effect in the surrounding area. (Pixabay)

As this hot summer has reminded us, tree canopies are excellent for providing shade and lowering surface and air temperatures.

The Environmental Protection Agency estimates evaporation from canopies can result in a 2- to 9-degree Fahrenheit reduction in peak temperatures, and shaded surfaces can be 20 degrees to 45 degrees cooler than unshaded areas. Along with their multiple other benefits, such as improving air quality, reducing noise and providing natural habitat, trees are a crucial element of public and ecological health.

In order to reap all the benefits of trees around your home for years to come, it’s important to keep an eye on their health. Watching their health not only ensures their benefits during the warm seasons, but it also provides the chance to tend to weak or broken branches before the high winds and early snowfalls of fall and winter make them a danger. Here are a few tips to help you assess the condition of your trees and identify problems before they worsen.

Check for signs of growth each year. Measure the circumference of the tree trunk annually at the same height each time to ensure it is still growing. Even a small increase is an indication of good health. You can also find the scars of last year’s buds and measure the distance between them and this year’s buds. The rate of growth will vary depending on species, so seek out information specific to the species of tree you are evaluating to determine if your tree is growing as expected.

Do bottom-up inspection. Look at the roots of the tree for any sign of decay such as soft areas. Next inspect the tree’s collar, where the trunk meets the soil surface. Pull back ground-cover and grass to check for decay such as missing bark or bark that is easily falling off, as well as any cracks. Examine the trunk for the same conditions. Then look up at the canopy and see if you can spot any broken or hanging branches or limbs that are missing bark and signs of new leaf or bud growth.

Evaluate the appearance of the leaves. Check that the color is seasonally appropriate for the species. Unless the species of tree has naturally variegated or has yellow leaves during the summer, you should expect to see green foliage on both deciduous and evergreen trees.

Yellowing or drooping leaves typically indicate too little or too much water, as well as a lack of balanced nutrients. Leaves that appear stunted or of irregular shape may indicate disease, insect or chemical damage or nutrient deficiency.

Know the signs of disease and pests. Chewed, puckered, dull, yellowed or distorted foliage are telltale signs. Also look out for white spots or cottonlike masses on branches and leaves. Wood-boring insects reveal their presence by leaving holes and dust in the bark. You can spot insect excretions, or “honeydew,” by spotting the development of mold on top of a sticky liquid left behind by insects after they feast on plant sugars.

Test the twigs and branches. Healthy twigs will be pliable and green. You can snap one off and check for green tissue beneath the bark. Dark, brittle twigs indicate the twig is dead. If you find a dead twig, check other twigs around the area and on other branches to see how much of the tree is dying and if it can be saved.

Be sure to cleanly prune the areas you broke twigs from to prevent infection or attraction of pests.

If you notice any signs of ill health in a tree, don’t hesitate to contact an arborist for professional help in restoring your tree and ensuring its benefits and beauty for years to come.

Rachel Baker can be reached at (509) 459-5583 or

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