Insecticides and Crop Protection

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 Deciding to spray | Alternatives to crop spraying | Common crop pests | Insecticides

This information is intended for residents of agricultural communities or residents that border agricultural fields.

Deciding to Spray

Spraying crops is not a decision that a farmer makes lightly. Spraying insecticides is expensive, costing between $10-$15/acre. Farmers will tolerate some damage to crops; up to the point where spraying offsets ecomonic losses. Economic thresholds are developed to assist farmers with spraying decisions. Farmers monitor fields with sweep nets to determine insect populations at critical crop stages. Then compare these numbers with established threshold numbers to decide if spraying is necessary.

Alternatives to Crop Spraying

Crop production in most of the developed world has evolved to accommodate large farms operated by fewer farmers. These large farming operations are highly mechanized and very dependent on technology. Farming practices are always evolving and, someday, it may be possible to manage extensive crop areas with reduced use of insecticides. Today, farmers select varieties, rotate crops, manage fertility, time seeding and employ other practices to reduce the likelihood and impact of insect pests. Alberta is fortunate that its climate tends to lower the incidence of insect outbreaks, decreasing the need for widespread insecticide spraying.

Common Crop Pests

The Lygus bug is an insect native to Alberta. It has been a noted pest of alfalfa seed fields for some 40 years. Recently, Lygus bugs have begun to affect canola crops to the point that spraying is necessary to prevent excessive crop loss. The most serious damage in canola is when the pod is forming, near the end of the bloom period. Lygus bugs suck the juices out of the developing seed or abort buds and blossoms. The Bertha armyworm damages canola by chewing on seed pods. The Diamondback moth feeds on the surface of immature canola pods. Seeds do not fill properly and pods are more susceptible to shatter prior to harvest. Grasshoppers primarily affect cereal crops. During extreme population outbreaks, they will consume all available plant materials.


Pesticides available for use in Canada have been reviewed and authorized by Health Canada. Insecticide chemistry is diverse, offering producers a range of options to suit specific pest problems, crop protection needs, and specific weather and field conditions. Provincial entomologists review insect forecasts and available insecticides to advise farmers of suitable choices. Ultimately, it is the farmer who selects which registered pesticide will be used.

The insecticides chlorpyrifos (Lorsban), trichlorfon (Dylox), and lambda cyhalothrin (Matador) are registered for Lygus bug control. Chlorpyrifos is a widely used insecticide for both indoor and outdoor pest control. The product has been used in Canada and the U.S. for the past 30 years (1969). Trichlorfon has been used in Canada and the U.S. for over 40 years (1956). Trichlorfon has also been used as a human medicine to combat internal parasites, primarily in tropical countries. It has also been used as a livestock insecticide. Both chlorpyrifos and trichlorfon are organophosphate insecticides. Matador is a synthetic pyrethroid insecticide. It was first registered in Canada in 1997.

Some other insecticides that may be used for agricultural spraying in Alberta include carbaryl (Sevin), deltamethrin (Decis), and cypermethrin (Cymbush and Ripcord).

This information has been developed and supported by:

Alberta Environment maintains a 24 hour toll-free line for environmental complaints and emergencies: phone 1-800-222-6514.
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For more information about the content of this document, contact Scott Meers.
This document is maintained by Shelley Barkley.
This information published to the web on November 7, 2001.
Last Reviewed/Revised on January 14, 2015.