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.

A survey of alfalfa bay producers was conducted to characterize vertebrate pest problems in Nevada alfalfa hay and help attract research funding. Damage to alfalfa bay by pocket gophers (Thomomys spp), ground squirrels (Spermophilus spp), black-tailed jackrabbits (Lepus californicus) and meadow voles (Microtus montanus) was assessed. Presence of vertebrate pests along with a ranking of cost-related problems they pose to alfalfa hay operations was determined. Pocket gophers were the most costly pest followed by ground squirrels, jackrabbits, and meadow voles. The number one problem caused by vertebrate pests was identified to be a decrease in hay production. Control techniques were rated as somewhat effective for all rodent and rabbit pests. The costs associated with farm management practices were ranked from highest to lowest in this order: irrigation, rodents and rabbits, weeds, insects, and fertilization.

Information concerning vertebrate pests of beekeeping was gathered from state and provincial apiary inspectors through a questionnaire. Forty-eight states and 9 provinces responded. Additional pest information has been assembled from published articles. Bears represent the major vertebrate pest based on severity of damage to colonies. Total estimated losses reported amounted to $623,000 annually. Loss estimates for the various pest species are probably grossly underestimated because many states with problems could not or did not provide loss estimates. Skunks and house mice represent the next most important species from a damage point of view, with annual damage averaging $423,050 and $100,450, respectively. Skunk and house mouse damage, although less severe than that of bears, is far more frequent and widespread. The principal method of damage prevention is the use of electric fencing for bears while trapping is the most used method for control of skunks. Exclusion is considered the best means of resolving house mouse problems. These and a variety of minor vertebrate pests are discussed along with methods or techniques used for their prevention and/or control.

A field trial was conducted to determine the efficacy of strychnine and zinc phosphide cabbage baits for controlling ground squirrels in Diamond Valley, Nevada. The reduction in aboveground ground squirrel activity was 83% for strychnine and 70% for zinc phosphide. Similar results were found for reductions in burrow activity: 88% for strychnine and 70% for zinc phosphide. Strychnine appeared to be slightly more effective than zinc phosphide, but both appeared to be effective for ground squirrel control.