Magazine article American Forests

IPM: Best Approach to Pest Control

Magazine article American Forests

IPM: Best Approach to Pest Control

Article excerpt

It's a beautiful summer day. You go out in your backyard to sit in the shade of your favorite tree. But to your dismay, you discover that caterpillars are gnawing away on leaves that are already partly chewed. What should you do?

A. Call a tree-care company and tell it to spray the tree with the most potent insecticide it has.

B. Ignore the problem and let nature take its course.

C. Prune the infested limbs, and Pull off all the caterpillars by hand.

D. Spray with a biological pesticide like Bt, which will kill caterpillars-and only caterpillars.

If this feels like one of those trick questions that made you dread multiple-choice tests, it's because there is no "right" answer. Depending on the circumstances, any one of these four approaches-or some combination of them-might be an appropriate way to tackle pests on lawn trees and shrubs.

Thirty or 40 years ago, the answer would have been immediate and unthinking: " Spray " At that point, pesticides like DDT seemed like miracle cures for pest problems. After all, DDT wiped out malaria in the U.S. almost single-handedly by eradicating the mosquitoes that spread the disease. As we eventually discovered, DDT also quickly worked its way into the food chain, where it damaged the nervous and reproductive systems of animals, including humans.

We understand a lot more now than we used to about the complexity of the natural world and how our attitudes affect it. We've learned that we can't keep pumping tons of chemicals into the environment without dangerous consequences. Our understanding of the dangers of pesticides and the horrible cycle we can get into when a pest builds up resistance to them is pointing the way toward a safer alternative-integrated pest management (IPM).

IPM is an approach to pest control that relies far less On blanket spraying of chemicals than on a sophisticated understanding of both plants and pests-the mechanics, chemistry, and biology of natural systems.

Applying IPM to ornamental landscaping doesn't necessarilly preclude spraying. It does require knowing enough about the plant-and the Pest-to be able to evaluate all the options for tackling a pest problem. The ultimate prescription to upgrade your tree's health is then based on short- and long-term effectiveness, environmental safety and cost, and integrating the best options into a management program. Pesticides are used only if nothing else works. The goal isn't to obliterate every pest on the tree but to achieve the maximum amount of good with the minimum amount of harm.

Looking at three landscape firms that have adopted IPM in recent years will give you some idea of how it works and what you can expect if you decide to try an IPM approach. The landscape companies featured vary in size from a small, locally known firm to a large, well-known tree-care company

White Oak Pest Management, Inc. of Manassas, Virginia, is small enough that its staff IPM expert, Ed Milhous, can give every site his personal attention. White Oak, which concentrates on small trees, shrubs, and ground covers, now bases its entire maintenance service on IPM. Milhous lists the elements in White Oak's intensive IPM program: "Good cultural (caretaking) practices, including the use of resistant varieties, proper pruning, fertilization, and mulching.

"Our service is built around the key-plant/key-pest concept," says Milhous. "A study at the University of Maryland several years ago indicated that certain plants in certain situations have a disproportionate share of troubles. For example, one would expect azaleas in the sun to have lacebugs, dogwoods in droughty spots to have borers, almost anything in a parkinglot island to have problems.

"We use the University's pest-appearance timetable to help schedule monitoring, and pay special attention to those red-flag plants and situations."

Milhous says his staff does a lot of pruning, almost always "drop-crotching" (cutting a branch off where it attaches to the tree) instead of shearing. …

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