Pesticide pitfalls: Common misuses and what to do if you’ve made a mistake

MACOMB, Ill. — You sprayed what? Where?

There are a few occasions when it is a good thing people can’t read my facial expressions over the phone. One of those situations is when I get a phone call where someone has used a pesticide that is way off-label. By off-label, I am referring to spraying a pesticide in a manner that is not listed in the directions or is even forbidden by the directions.

Because these instances keep reoccurring year after year, I am assuming I am only getting a tiny fraction of phone calls from a greater amount of people who may be frantically searching the internet for answers to pesticide misuse. So, with the hope I can reach more than the handful of folks who call or email me personally, the following are some common instances of spraying a pesticide where it should not be used and the recommendations for what to do next.

Spraying chemical insect barriers on the vegetable garden

This might be the most common “You sprayed what?!” call I get each year. This situation often involves a thrifty spouse (typically a male) who buys an insecticide barrier to spray around the perimeter of a home. With a little extra pesticide remaining in the jug, their logic dictates that if this chemical kills bugs coming into the house, it will kill bugs eating the vegetables. They then spray their vegetable garden with the home defense spray.

Spraying a chemical insecticide barrier on your vegetables is off-label and often listed with a stern “Do not do that!” on the label. One reason is that chemical barrier insecticides are designed to persist in the environment. A majority of insecticides labeled for food crops are designed to degrade within a certain period. All labeled pesticides meant to be sprayed on vegetables will list the time needed to wait from spraying until food can be harvested, usually referred to as the pre-harvest interval.

What happens to a vegetable garden that has been sprayed with a chemical barrier insecticide? Well, I called up a few companies that make these products to get their take, and they all said no produce can be harvested from the garden for at least one growing season, and the garden must remain fallow for one year. I know squash bugs are a pain, but we still want to be able to eat some zucchini.

Spraying Tordon on Lawns

It seems more people are falling in love with a brand called Tordon, which has become very popular for killing weeds. And rightly so, as it is very effective at killing broadleaved plants. It is becoming more common to see recommendations for using Tordon RTU, whose active ingredients are picloram and 2,4-D, on lawns. Yes, this product will kill dandelions and clover. However, I have seen it routinely kill landscape trees and shrubs. This is because one of the active ingredients, picloram, is highly soluble in water and readily moves in the soil, affecting non-target plants.

Be aware that the manufacturer of Tordon RTU clearly states on the label in bold lettering, “Tordon RTU should not be applied on residential or commercial lawns or near ornamental trees and shrubs.” Despite the clear labeling, some retailers still market this as a lawn herbicide.

Unfortunately, I have witnessed several homeowners lose valuable shade trees, hedges, and even an entire windbreak of evergreens, in their effort to kill some dandelions. Tordon can remain toxic to plants for a year or more in the soil and can easily move into surface or groundwater.

Good Growing Tip of the Week: Examples of pesticide misuse are numerous, but these products remain important tools. When considering pesticides, learn about your particular pest, use pesticides as a last resort, and always follow label directions.