Why zinc phosphide mouse bait needs a higher rate to work
Bill Crabtree, Agronomist at 4Farmers, joins Country Hour to discuss the growing mouse pressure across WA’s agricultural region, with some areas north of Geraldton recording up to 8,000 mice per hectare. Bill explains the combination of factors driving the outbreak, including a good 2024 harvest leaving grain on the ground, reduced pasture cover, and three significant weather events over summer. He outlines why 4Farmers has applied to the APVMA for an emergency permit to manufacture zinc phosphide mouse bait at 50g per kilogram, double the current standard rate, citing research by CSIRO’s Dr Steve Henry showing that the lower 25g rate is not achieving effective kill because mice become shy feeders. Bill also addresses concerns around secondary poisoning, pointing to an APVMA document from 2000 confirming that zinc phosphide breaks down rapidly in soil and leaves negligible residue.
Bill Crabtree — Country Hour
ABC Radio interview · 8 April 2026