Overview
- The national regulator, which granted the emergency permit Monday, will allow manufacture and sale of 50 g/kg zinc phosphide bait known as ZP50 for use where mouse numbers are high.
- Grain Producers Australia secured the permit and growers must complete mandated training, with strict directions on when and how to spread bait to limit risks to people, wildlife and the environment.
- CSIRO studies found ZP50 kills more reliably because one treated grain can be lethal, whereas the standard 25 g/kg bait often needs two or three grains and fails when paddocks are full of other food.
- Field surveys report extreme densities in Western Australia’s grain belt, including estimates near 8,000 mice per hectare, and towns such as Northampton and Morawa are seeing home invasions, chewed wiring and spoiled food.
- The approval is temporary and framed as an emergency step, with GRDC and CSIRO supporting rollout and monitoring, further research under way on non‑target impacts, and officials warning the bait is for farms and not a stand‑alone fix for urban infestations.