Proceedings of the Vertebrate Pest Conference

Both ground squirrels and pocket gophers are significant pests in urban, rural, and agricultural settings within California. Various techniques are used to control these “pest rodents”; however, this presentation will explore the use of carbon dioxide (CO2) gas as a fumigant to control these rodents in their burrows. These studies were conducted to support efficacy submission requirements for the US Environmental Protection Agency (EPA) and selected state regulatory agencies in California, Washington, and Oregon. The Eliminator® System, Inert Gas Injection, LLC (IGI) was used for delivery of the carbon dioxide gas (cylinders) into underground burrows. Pre-treatment and post-treatment monitoring, visual counts, and burrow activity were used to determine the efficacy of the burrow fumigations. Carbon dioxide gas treatment of ground squirrel burrows resulted in 93.6-84.3% reduction in visual ground squirrels in the treatment plots 5-7 days after treatment, respectively, compared with untreated plots. CO2 gas treatment of ground squirrel burrows resulted in 71.5 ± 4.3% to 67.8± 4.3% reduction of reopened ground squirrel burrows in the treatment plots 1 and 5 days after treatment, respectively. In the pocket gopher trial, there was no evidence of tunneling or mound building in the treated test plots for 4 days after the last CO2 treatment, demonstrating 100% effect of the CO2 treatments against gophers with the Eliminator® System.