Mice numbers stalling winter cropping

Mice numbers stalling winter cropping

Mice numbers have continued to rise in the last year, especially after last year’s record harvest. IMAGE: CSIRO

Mice are decimating crops, ruining grain stores and chewing through farm machinery wiring in the worst plague for 10 to 20 years.

The impact has stretched across Australia’s wheatbelt, with record numbers of rodents breeding over the summer.

The problem area stretches from Central Queensland into Northern NSW, throughout the Central West and Western NSW into the Southern Riverina.

High numbers are also reported in South Australia’s Wimmera and Mallee regions, with higher than usual numbers in the Ravensthorpe area of Western Australia. 

Reported numbers are as high as 450 mice per hectare in Parkes, NSW. 

Mouse_Abundance_GRDC_March21Grain Research & Development Centre’s five quick tips for mouse control:

  • Apply broad scale zinc phosphide bait: According to the label, at the prescribed rate of one kg/ha.
  • Apply bait at seeding or within 24 hours: While seed is still covered by soil increasing the likelihood of mice taking the bait, prior to finding the seed. Rebait through the season as needed.
  • Timing is critical: Delays of four to five days in baiting after seeding can give mice time to find crop seed. High populations can cause up to five percent damage each night.
  • Monitor paddocks: Check paddocks regularly and update local data using the MouseAlert website.
    • After harvest and prior to sowing – minimise sources of food and shelter: Control weeds and volunteer crops along fence lines, clean up residual grain by grazing or rolling stubble. 


Even though conditions are ideal for sowing, some NSW farmers have held back on seeding their winter crop. They hope mice numbers will fall as the weather cools.

Losing an entire crop at time of seeding or having it almost entirely damaged at, or prior to, emergence are the threats currently faced.

Baiting is the current focus. In-paddock baiting with zinc phosphide just before sowing or at sowing is a popular process, with the NSW government offering assistance as part of a $50 million package to tackle the problem. 

They aim to provide free baits to all primary producers, establish eight grain poison treatment stations, offer bait rebates to small businesses and property owners, and host seminars in regional areas on how to approach the issue.