Pesticides are safe when used properly | THE EVERGREEN ARBORIST

It is wise to understand some important facts before you use pesticides.

  • Friday, March 17, 2017 8:00am
  • Life

By Dennis Tompkins

This is the time of year when many insect and disease pests will soon wake up and lick their chops as new growth emerges on trees and shrubs in our landscapes.

Some homeowners use pesticides to attempt to control these pests. However, before making final plans it is wise to understand some important facts.

What is a pesticide?

Pesticides are products used by humans to kill anything they consider a landscape problem – a weed, a bug or a fungus. The most common treatments include insect (insecticides), disease (fungicides) and weed killers (herbicides). Pesticides also include many household goods like bleach and other cleaning products to kill germs in our homes.

Who uses pesticides?

Did you know that homeowners use more pesticides than farmers in the Puget Sound area? While most homeowners are responsible, there are some who believe that “if one glug works, two must be better.” Not true!

What about farmers? Let’s face it, folks. When shopping for groceries, we would not purchase a scab-covered apple, a wormy ear of corn or an aphid-covered head of lettuce.

America’s farmers view pesticides as “crop protection insurance” for two reasons: 1) to produce the blemish-free, high-quality products we consumers demand; and 2) to help make their operations profitable to justify remaining in business. While the organic movement is growing, it is difficult to economically justify such practices in many instances.

Farmers consider themselves environmental stewards of the land. They do not wish to poison themselves, their workers, their land or the ultimate consumer.

How safe are pesticides?

Pesticide use can be a very emotional topic. The anti-pesticide crowd is quite vocal and sometimes controversial. Unfortunately, because of the rhetoric and fearmongering that often occurs, it can be difficult to sort out the facts and truly appreciate the contribution that pesticides have made to our standard of living and well-being.

When used with care and according to labeled instructions, pesticides are quite safe. It is the rate of exposure, not the mere presence of pesticides, that should be of concern.

Many public agencies continuously monitor various sites to determine the presence of elements that might be of concern. The amounts in local waters are nearly always far below toxic levels.

Three rules for responsible use

  1. Determine the identity of the pest. This is often easier said than done. Master Gardener clinics, extension services and consultants are good sources for assistance.
  2. Learn which pesticides are legal and effective for the identified pest. This requires careful reading of pesticide labels.
  3. Apply the pesticides at the proper time. For example, if a treatment will only kill adult insects, do not apply it before they are present.

Generally, my first choice is to live with the problem if it does not threaten the health or appearance of a tree or shrub.

Fungicides are generally applied to prevent various diseases from infecting susceptible new leaves. Insecticides are most often used after an insect attack has become serious enough to warrant control. Weed killers can be used either before or after an offending plant has started growing – depending upon the weed and type of chemical.

Are spray services necessary?

Some homeowners use services that apply pesticides on a programmed schedule. These services have a real challenge because their success often depends upon weather conditions. Some pests have a narrow window of opportunity for effective control. If foul weather prevents applications within these windows or if rain occurs shortly following application, the treatments may not work.

Homeowners place great trust in such services. However, it is a good idea to inquire and be aware of the chemicals to be used and the pests that are targeted. A greater understanding of a spray program will help homeowners to decide if it is truly appropriate for their individual circumstances.

Dennis Tompkins, a Bonney Lake resident, is an ISA certified arborist and ISA qualified tree risk assessor. He provides small-tree pruning, pest diagnosis, hazard tree evaluations, tree appraisals and other services for homeowners. Contact him at 253-863-7469 or email at Website:

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