Proceedings of the Vertebrate Pest Conference

The Townsend pocket gopher (Thomomys townsendii) poses a serious economic threat to alfalfa production in Diamond Valley, Nevada. Many control methods have been practiced with only limited or seasonal success. Application of strychnine-treated alfalfa hay has been an effective control method; however, the relationship between strychnine concentration and pocket gopher kill has not been examined. This study was conducted to evaluate the effectiveness of three concentrations (0.5%, 1.0% and 1.7%) of strychnine-treated alfalfa hay baits. The three strychnine levels and untreated control were replicated three times on twelve 0.8-ha (2.0-ac) plots. Plots were located on a 6-year-old stand of sprinkler-irrigated alfalfa. Pocket gopher activity, (mound count census method), was monitored pre- and post-treatment to estimate bait effectiveness. Data were evaluated by regression analysis of variance. Average percent changes in gopher activity were +24%, -40%, -78%, and -69% for treatments 0%, 0.5%, 1.0%, and 1.7%, respectively. There was a significant (P<0.01) negative effect of strychnine concentration on pocket gopher activity.