There are some occasions when it’s a good thing that people can’t read my facial expressions on the phone. One of those situations is when I get a call from someone who has used a pesticide that is way outside of the approved uses. By “off-label” I mean spraying a pesticide in a way that is not listed in the directions or is even prohibited.

Because these cases repeat year after year, I expect that I only receive a fraction of the calls from a larger number of people who may be desperately searching the internet for answers about pesticide misuse. In the hopes of reaching more than the handful of people who call or email me personally, below are some common cases where a pesticide is sprayed when it shouldn’t be used, along with recommendations for how to proceed.

Spraying chemical insect repellent in the vegetable garden is probably the most common “You sprayed what?!” call I get every year. This situation often involves a frugal spouse (usually a man) buying an insect repellent to spray around the house. Since there is a little pesticide left in the bottle, their logic dictates that if this chemical kills insects that come into the house, it will also kill insects that eat the vegetables.

Then they spray their vegetable garden with the home repellent spray.

Spraying a chemical insecticide barrier on your vegetables is not intended and will often come with a stern “Don’t do that!” warning on the label. One reason for this is that chemical barrier insecticides are designed to persist in the environment. Most insecticides approved for use on food crops are designed to break down within a certain period of time. All labeled pesticides intended for spraying on vegetables will indicate the length of time to wait between spraying and harvesting the food. This period is usually referred to as the pre-harvest period.

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

It seems that more and more people are falling in love with a brand called Tordon, which has become popular as a weed killer. And rightly so, because it effectively kills broadleaf plants. Recommendations for the use of Tordon RTU, whose active ingredients are picloram and 2,4-D, on lawns are becoming more and more common.

Yes, this product will kill dandelions and clover. However, I have seen it regularly kill landscape trees and shrubs. This is because one of the active ingredients, picloram, is highly water soluble and moves easily in the soil, affecting non-target plants.

Note that the manufacturer of Tordon RTU clearly states on the label in bold letters: “Tordon RTU must not be used on residential or commercial lawns or near ornamental trees and shrubs.”

Despite clear labeling, some retailers still market it as a lawn herbicide.

Unfortunately, I have witnessed several homeowners lose valuable shade trees, hedges, and even entire evergreen windbreaks in an attempt to kill dandelions.

Tordon can remain toxic to plants in the soil for a year or more and can easily enter surface or groundwater.

There are numerous examples of pesticide misuse, but these products remain important tools. When considering pesticides, educate yourself about your specific pest, use pesticides only as a last resort, and always follow label directions.