tree photo
An ash tree,with the severe die-back of its upper branch due to severe stress
Courtesy of Prestige Tree Experts

Sure, a lot of us are feeling stressed these days. It’s tough out there. But we’re not the only ones. Think of the trees!

Those of us who own homes with yards and trees may not be aware that our trees can be struggling with the stresses of insufficient water, or too much water, or compacted soil, or lack of nutrients, or insects or fungi, or nicks and cuts from mowers and trimmers. It’s tough out there.

To help us learn how to hug our trees more effectively, the West Laurel Civic Association brought in arborist Matthew Derrick on Feb. 15.  

Derrick, co-owner of Laurel-based Prestige Tree Experts, gave the following advice in that talk and in a consequent interview.

The best time to plant trees is spring or fall. Avoid planting in compacted soil — a tough order given the dense clay of our region — because the trees’ roots need air and water pockets in the soil. If your yard is mostly compacted, consider replacing some of the soil.

If you plant trees in spring, you’ll need to water them two to three times a week if the summer is especially dry. The same holds true for trees you plant in fall or even winter, including  evergreens. Deep, less frequent waterings are better than more frequent shallow ones, because that encourages deep rather than shallow root growth.

Mulch is magic for trees. A 2- to 4-inch deep circle of softwood or hardwood mulch with a radius of about 7 feet helps hold water in the soil and provides nutrients as the mulch decomposes. The mulch also suppresses grass and other plants that compete for water and nutrients. It also lowers your temptation to mow too close to the tree, which can  cause nicks in its trunk or roots — those open cuts can allow pests to damage the tree.

But remember, “Don’t get burned, avoid the volcano.” Piling mulch into a peak around the trunk of the tree is an open invitation to disease and pests, including small mammals. It can also lead to disease and rot. Keep the mulch low where it’s closest to the trunk — no more than an inch deep. .

All trees can profit from fertilizer. It’s their version of multivitamins. You can have your soil tested to measure pH and assess if you need to use a specific fertilizer. 

As for pests, there are a host of them: fauna such as spider mites, aphids, tent caterpillars, bagworms and scale, and fungi such as cherry leaf spot, rhizosphaera needle cast, anthracnose, shothole, scabs, rust and shelf fungus. Almost all yards have some of these present; that’s the bad news. The good news is that there are effective chemical treatments for almost all of them.

One of the most visible pests, but ironically one of the least threatening, is the tent caterpillar. You can simply cut the bags of caterpillars off.

Leaves are an indicator: pay attention to those that have brown or black dots, or are covered with a black, sooty mold or show a sticky excretion called honeydew. They may signal the presence of tiny insects or fungal infections. Arborists can fight these by injecting chemicals into the ground around the tree, thereby limiting toxic exposure to children and pets. Many of these treatments are best done annually, though combatting some pests, such as cherry leaf spot, calls for three treatments during the year.

Arborist services such as these can range from about $100 for a single treatment to $300 or $400 for multiple treatments, Derrick said.

The biggest sign of stress is when a tree’s leaves turn brown or drop off during the active summer growing season. Homeowners should be particularly concerned about leaning trees, especially when the soil  begins to crack at the base of the tree. That is a red alert that the tree may topple.

Even the most coddled, cared-for trees have a natural life span. Oaks, for instance, might last for 80 to 90 years in a yard (as opposed to in a forest, where the nutrients provided by the annual leaf-fall promote longer life spans). 

Derrick noted that our region has seen more oaks dying in recent years, spurred by bacterial and fungal diseases such as bacterial leaf scorch and oak wilt. Arborists can counsel you about an oak’s health and advise you about possible treatment to prolong its life.