Effects of bait formulations on toxicant losses and efficacy

During application by airplane, excessive amounts of zinc phosphide were lost from the bait registered to control rat damage in Hawaiian sugarcane. The losses created unnecessary hazards and potentially reduced the efficacy of the control program. In a series of screening tests, alternate adhesives, adhesive concentrations, and bait mixing procedures were evaluated for zinc phosphide retention, acceptance by rats, phosphine residues in sugarcane and operational effectiveness. A formulation was developed that reduced zinc phosphide losses 92% during application, increased acceptance by rats, left residues in sugarcane below the established tolerance, and equaled or exceeded the performance of the original formulation