Proceedings of the Vertebrate Pest Conference

The Nevada Department of Agriculture acquired the authority to control vertebrate pests of agriculture and public health in 1975. Prior to the Department becoming involved in vertebrate pest control, agricultural producers did not have ground squirrel baits which were very effective. The Department examined products used in surrounding states and due to the effectiveness of sodium monofluoroacetate fresh cabbage baits used in Modoc County, California, began using strychnine cabbage baits. Strychnine was chosen as a toxicant rather than sodium monofluoroacetate because it was thought to be less “toxic” politically. Fresh chopped cabbage baits were initially broadcast above ground in swaths or near active ground squirrel burrow openings. Due to the prohibition of above-ground uses of strychnine which resulted from a 1988 U. S. District Court ruling, the Department changed the labeling of its strychnine paste concentrate. Ground Squirrel (and yellow-bellied marmot) baiting directions now require bait to be placed 6 inches or more into burrow openings. The change in application procedure reduced the effectiveness of chopped cabbage bait, however it still surpasses the effectiveness of grain based baits due to the attractiveness of the cabbage to ground squirrels in Nevada. Baits are usually prepared on site by the producers who apply it immediately after formulation. One application in early spring prior to the emergence of juveniles is the optimum time for baiting. Follow-up applications may be made on surviving ground squirrels or when ground squirrels migrate in from other areas later in the season.