Landowners have been looking for other ways to control Richardson’s ground squirrels since the use of strychnine for that purpose was banned this spring.  |  Mike Sturk photo

Prof urges caution when using zinc phosphide

Vet says the main strychnine replacement for controlling Richardson’s ground squirrels can also poison other animals

Strychnine might be out as a pest control tool in Canada but one of the main replacement rodenticides to control Richardson’s ground squirrel populations needs special attention in its use as well, says a University of Saskatchewan veterinarian. Dr. Vanessa Cowan, assistant professor of toxicology at the Western College of Veterinary Medicine, said zinc phosphide […] Read more

A Richardson's ground squirrel stands on its hind legs to get a better view.

You can’t gopher strychnine anymore

James Tansey, Saskatchewan provincial specialist of insect and pest management, said the Saskatchewan government did not support the removal of strychnine and it presented data to the PMRA that showed the product could be used safely and effectively for the control of gophers. 


A Richardson's ground squirrel stands in the foreground, a cow is grazing in the background.

Gopher control enters the post-strychnine era

Product $/acre


James Tansey, Saskatchewan’s insect and vertebrate pest management specialist, said all the registered products in the study worked, but based on the data, he recommended those containing zinc phosphide.



A Richardson's ground squirrel stands on its hind legs and eats the seeds from the head of a bent over wheat stalk.

Loss of strychnine a long time coming

Pesticide was deregistered from 1992-2001, and the process to ban the product began again in 2020 after a 2018 review

The pesticide, registered in 1928, had already been deregistered from 1992 to 2001 over environmental concerns and a 2018 review found the same issues with the potential for secondary poisoning.