Regulations and pesticide labels vary by state, so be sure to check your state regulations before implementing any control technique. Depending on the specific situation, toxicants, trapping, or habitat modification may be more effective than fumigants. The problem stems with the porous nature of the vole burrows, making it very difficult to achieve toxic levels of the fumigant.
If you decide to use fumigants, it will be necessary to conduct this operation from several locations across the infested area. Because of the obvious fire hazard from gas cartridges and smoke cartridges (aluminum phosphide tablets are not flammable), this method should be approached with extreme caution in drier locations. Do not attempt this method near structures, as the tunnels may allow toxic fumes to enter. As with all pesticides, read and follow the label instructions.
Snap traps baited with peanut butter and oatmeal may be placed at the mouth of the tunnels to control voles. Remove mulch or vegetative litter from around the the base of plants to discourage vole damage. If legally registered for voles in your area, gas cartridges, smoke cartridges, or aluminum phosphide tablets may be used to fumigate vole tunnels for vole species that burrow underground. However, fumigation is very time consuming and often not very effective due to the complexity of vole tunnels.
Additional information on vole management can be found at:
Voles
Vole publication
