EXIT™/VARGON™ -- a new reduced-risk rodenticide for the control of burrowing rodents

Abstract

Author(s): McCulloch, Wally | Abstract: EXIT™/VARGON™ is a new, reduced risk, non-toxic, environmentally friendly rodenticide developed in Canada. The product will be marketed as EXIT™ in Canada and VARGON™ in the United States. United States, Canadian and international patents have been applied for. The product was given reduced risk status for the control of burrowing rodents in May 1999 and has been accepted for joint review by the PMRA and EPA under the North American Free Trade Agreement. Laboratory and field research trials conducted within both the United States and Canada to determine efficacy for control of ground squirrels (Spermophilus spp.) showed 100% efficacy in the laboratory and 94% to 98% efficacy when used in the field according to label directions. Laboratory trials conducted in Canada to determine efficacy for control of Norway rats (Rattus norvegicus) showed 100% efficacy in the laboratory. Preliminary field trials have been carried out with promising results. EXIT™/VARGON™ is a concentrated mixture of alpha-olefin sulfonate and mustard seed powder (Brassica hirta) in water. Prior to application, the concentrate is diluted 1 part concentrate to 24 parts water to form the field solution. The field solution is applied as a foam to individual burrows through an air-aspirating nozzle. All treated animals become unconscious due to anoxia within 1 minute and death by asphyxiation occurs in less than 3 minutes from the start of application. Application equipment consists of a water tank, 12-volt 3.6-gpm Shur Flow pump, a hose reel, and 100 feet of ½-inch garden hose. The nozzle is a 3-gallon per minute aspirating nozzle with a 12-inch to 16-inch extension tube to create foam. The foam expands 3 to 4 times as it exits the nozzle and fills most burrows in 15 to 20 seconds. Prior to application, burrow entrances are blocked with a wire basket or perforated plastic cones to prevent escape of target animals. Foam is applied through the basket or cone into the burrow. The product can be applied at any time and does not depend on the feeding patterns of the target species for efficacy. Application can be made in early spring prior to emergence, throughout the summer when the animals are active, or in late fall after the rodents begin to hibernate. Burrows must be examined and certified free of threatened or endangered species prior to using EXIT™/VARGON™. The product is very site specific, and selected areas such as playing fields, grazing areas, parks, etc. can be targeted for treatment while wildland areas can be left as habitat for the ground squirrels. Periodic treatments will keep the selected areas free of target species. The product is biodegradable, environmentally friendly, and essentially non-toxic. It is safe to handle and easy to apply. Treated animals die and remain in their burrows. As the product has no systemic toxicity, there is no secondary poisoning risk to humans or other species.