Trees get stressed, too: Recognize these signs so you can nurse yours back to health

You might notice the trees planted around your home aren’t thriving as they once did.

Trees planted in cities, towns and along roadways tend to live decades shorter than those that grow in forests due to many potential sources of stress to which they can be exposed.

Younger trees tend to be more vulnerable to mechanical bark damage, be it environmental or human-caused, said Gena Lorainne, horticulturist and plants expert at Fantastic Services.

“Some species of trees are also more sensitive to rapid climate change than others,” Lorainne added.

How trees become stressed

Human-caused and environmental stress factors may include pests that attack a tree or feed on the leaves; fungal problems; viral and bacterial issues; an overabundance or lack of water; extreme temperature swings; a change in soil level; excessive pruning; and root damage or compaction, according to Mark Chisholm, a professional arborist and spokesperson for outdoor power equipment manufacturer Stihl.

“There are [also] lightning strikes, frost cracks on the bark of the trunk, hail damage, sunscald from excessive sunlight, flooding and drought,” Lorainne said.

“Some of these, although environmental, could be avoided by a better positioning of the tree when planting,” Lorainne added.

Improper planting can also result in a stressed tree. “When planting a tree, it's extremely important to dig the right depth for the root system to develop properly,” Lorainne said. “The hole should be at least three times wider than the width of the root ball of the tree.”

Lorainne advised avoiding areas with lots of foot or vehicle traffic, as this compacts the soil, which impedes the root system's ability to penetrate through the ground and reach for nutrients and water underneath.

Compacted soil also means bad drainage and reduced oxygen, according to Lorainne. A properly planted tree can increase the lifespan by decades.

Additional human-caused stress factors include improper mulching, wounding the tree with lawn tools, road salt applications during the colder months and over-fertilizing.

“Over-fertilizing may result in quick growth, but [the tree will be weak and] prone to disease,” Lorainne said. “An imbalance occurs as most of the nutrients are used for growth and [used far less] for defense mechanisms against pests.”

Signs to watch out for

When identifying whether your tree is showing signs of stress, be sure to look for symptoms including the following:

If there's any fungal growth on the tree's trunk or at its base, it's usually a bad sign of a low-pH soil or the tree rotting from inside, said Lorainne.

Restoring your tree’s health

“Proper care before a problem presents itself will greatly enhance a tree's ability to combat it,” said Chisholm, who recommended seeking professional advice if you’re stumped about what’s wrong with your tree.

Once the problem is identified, you can work to address the stressor, he said.

According to Lorainne, tree owners can try aerating the compacted soil, which may require special treatment; applying organic mulch 2-3 inches deep around the tree’s roots while avoiding the trunk; removing dead or diseased branches and twigs; generously watering a parched tree; and observing and familiarizing yourself with your tree.

“Every spring is a good time to inspect your tree for potential pests and diseases,” Lorainne said. “Educate yourself on the tree's growth rate, coloration and development stages so that if you notice that something is off, you know there's a problem.”

Don’t panic if you spot a potential pest on your tree, she said, as trees can usually withstand a certain amount of them.

“It's considered a problem only if the pest colony is growing out of control,” Lorainne said. “If you have a larger tree, you'd want to talk to a certified arborist about treatment.”

Lorainne also advised researching the tree you plan on planting, making sure that the local climate is suitable for it to grow healthy and strong.

“It should also be positioned well to ensure enough, or not too much, daily intake of sunlight,” she added.