How to Protect Trees From Insects and Pests

Tree work can be challenging, and pest infestations can make it even harder. Here are tips to protect trees from insect infestation.

Some infestations can cause the bark on trees to peel.
Some infestations can cause the bark on trees to peel.

Between blistering heat waves and wildfires, trees are facing lots of stressors and are more vulnerable to new problems such as insect invasions. You might be getting more calls from property owners who aren’t sure what to do, and a brushup on the basics doesn’t hurt.

Good Health Equals Good ImmunityA large tree with full and green leaves is a sign of health.A large tree with full and green leaves is a sign of health.judydean/

Trees, like any living organism, are best able to fight off threats if they begin in good health. It’s also the easiest and cheapest way to fight off insects or other pests and one of the most important tools in your toolkit.

As we settle into the fall in a couple months, the seasonal change might tell you something about your trees if their colors are not in sync with the trees in the neighborhood. If the days are warm and the nights are crisp, but the trees are not colorful, it might be a sign that the trees aren’t getting enough moisture or are suffering from heat stress.

In the spring, a tree that isn’t producing leaves as quickly or energetically as other trees in the area may be planted in poor soil or the roots may be restricted in some way. Leaf health can be closely tied to nutrition, and amending the soil can solve the problem. Dead or dying leaves can also be a sign of insects or diseases.

A good green industry professional also knows pruning does a tree a lot of good if it’s done at the right time for the right reasons. Sometimes it’s hard to sell a customer on regular pruning, because to untrained eyes it looks like you’re just cutting the tree back.

You’ve probably heard the saying that the best defense is a good offense. It applies to trees as well as football teams, and your customers should know that keeping trees healthy is much easier than trying to fight off an infestation that could permanently damage or kill them.

Let's say you do spot signs of trouble like holes chewed in the wood. Let’s get into some of the ways to protect trees from an active threat.

From Pest to Prey 

Turn tree pests into prey using microbial materials, like bacteria, fungi or a virus that targets the bugs that are causing the infestation. A good example of this is bacillus thuringiensis (BT), which attacks different insects, depending on the strain. The right kind of BT will knock out gypsy moths. Milky spore is another example of a microbial insecticide that kills the larvae of the damaging, metallic green Japanese beetle.

Natural Deterrents

Natural materials should be part of a pest control plan. A property owner or landscaping crew can easily use neem oil, or occasionally spray soapy water on the trees on their own. You may suggest it to them if they have a low-level problem with their trees. These methods are less likely to kill beneficial bugs and organisms, and many customers are on board with preserving the living beings that serve a human purpose in outdoor green spaces.

However, don’t let clients assume so-called natural materials are automatically less toxic than synthetic ones. One example is pyrethrum, which kills most insects on contact. Pesticides are often effective at eradicating pest and insect infestations.Pesticides are often effective at eradicating pest and insect infestations.Lawnstarter

Chemical Intervention

By the time a customer is calling for a green industry pro for help, it’s often time for a chemical intervention when the infestation is pretty big and there is lots of damage or the property owner is confused about how to go about containing the problem.

Chemical methods are encouraged as a last-resort method, but they work very well at getting rid of an out-of-control pest problem.

Be aware that you, as a pro, may still need special training and certification from your state in order to use some of the most toxic chemical interventions.

A Systemic Approach

Systemic means the whole tree will absorb the chemicals, and then the absorbed technical materials go on to kill insects as they attempt to feed on the tree. A good example of this is the treatment for the emerald ash borer (EAB), which is the most damaging insect in North America.

The threat posed by the EAB is such that soil-applied systemic pesticides, trunk-injected systemic pesticides and noninvasive basal trunk sprays are among the most common methods of dealing with the invasive beetles.Moths such as these are common pests to look out for in trees.Moths such as these are common pests to look out for in trees.Wikimediacommons

Kill an Insect, Save a Tree

If left untreated, pests can kill trees and dead trees will need removal. It can be a sad day to see some old giants fall to pests, and you’re the professional who can not only manage the logistics, but you can educate homeowners or facilities management about how they can begin to protect their trees long before extreme measures have to be taken.