These regulations are subject to change. When using a fumigant as a follow-up to a baiting program, treat only active mounds. This greatly reduces the amount of fumigant used. To identify active mounds, shovel or blade the soil or place a dry cow chip over all holes. It is important to begin treatment the day after plugging holes because one prairie dog will uncover several holes in three or four days.
Fumigants are most effective when soil moisture is high.
To use the gas cartridge, punch at least five or six holes in one end with a nail or ice pick. Insert the sharp point part way and rotate it to loosen the contents so the cartridge will burn more rapidly. Insert and light the fuse. Once the fuse is burning well, gently roll the cartridge as far back into the burrow opening as possible. Do not cover or smother the cartridge.