Poor results after baiting usually are due to improperly placed bait, failure to prebait, presence of green vegetation, or inactivity of a portion of the ground squirrel population. Fumigants Use fumigants when additional control is required. Aluminum phosphide and gas cartridges are registered for use in Colorado. Trade names for aluminum phosphide include Phostoxin, Gastoxin and Fumitoxin. Aluminum phosphide is classified as a restricted use pesticide and gas cartridges are classified for general use.
Fumigants are most effective when used in moist soils in early spring.
Aluminum phosphide is classified as a flammable solid. Transportation of aluminum phosphide by commercial firms is governed by U.S. Department of Transportation rules and regulations. These regulations are subject to change. Then insert a wadded newspaper and plug the opening to the burrow with moist soil or a plug of sod placed grass-side down to form an airtight seal. The wadded newspaper prevents the fumigant from being covered and may delay ground squirrels from digging out before the tablets activate.