Double-strength bait given go ahead to fight mouse plague

Farmers fighting the mouse plague have been granted permission to use bait that is twice as toxic as normal poison
Double strength mouse baits will help farmers fight the overwhelming mouse plague that is destroying crops and causing significant damage to stored hay and grain

Research funded by the GRDC and conducted by CSIRO has enabled evidence-based increases to zinc phosphide (ZnP) mouse baits.

ZnP-coated wheat bait is the only registered in-crop rodenticide for the management of mice damage in broad-scale agriculture in Australia. The new Australian Pesticides and Veterinary Authority (APVMA) emergency use permit increases the concentration of zinc phosphide active per wheat grain from 25 mg/kilogram to 50 mg/kg.

The bait will still be applied on-farm at one kilogram per hectare but will have twice as much ZnP on each grain, increasing the likelihood of a mouse consuming a lethal dose in a single feed.

CSIRO researcher, Steve Henry, who led the study said the lab findings showed the bait prepared at this new mixing rate was lethal in all mice while the previous bait mixing rates was only lethal in 50 per cent of mice.

“It is critical that every grain of bait represents a lethal dose,” Mr Henry said.

“Our lab research has shown that mice rapidly develop aversion to the bait, meaning that if they do not consume a lethal dose from one grain of bait, they will not consumer any more toxic grain.”

GRDC Pests Manager, Leigh Nelson, said the increase in bait mixing concentration was expected to be well received by industry.

Dr Nelson said current farming practices that conserved water and were environmentally sustainable, such as minimum or zero tillage, had resulted in a significant increase in both available shelter and alternative food sources for mice.

“Mouse management requires an integrated approach and a key part of this is the reduction of alternative food sources, such as grain being left in the paddock post-harvest. This residual grain greatly reduces the probability of a mouse encountering and consuming a treated grain,” she said.

“So even with the increased bait mixing concentration, growers will still need to ensure they implement best practice tactics on farm for effective mouse control.”

Latest information on Mouse Management is available on the GRDC website here.

For more information on the APVMA zinc phosphide/mice permit (PER90799) go to Agricultural And Veterinary Permits Search – portal.apvma.gov.au.