The number of mice caught in one night per 100 traps is used to assess the population level. Begin treatment when population is moderate. Baits Toxic baits are necessary where mouse problems are serious. Use a mechanical broadcaster to apply bait. Monitor areas around the field and treat them as needed, at any time of year.
Zinc phosphide requires only one feeding to be lethal.
Bait shyness, a condition that results when meadow mice consume only enough to make them sick and then discontinue feeding, is a potential problem with zinc phosphide. Follow label instructions to limit the potential for bait shyness, and do not treat more often than every 6 months. Anticoagulant baits may not be used in some crops at any time of year, but they can be used at any time along fence rows and in the surrounding noncrop areas. To be effective, meadow mice must consume an anticoagulant over a period of at least 5 days. Therefore, the bait must be available to the mice until the population is controlled.