Tips to abate mice threat to bumper harvest - Elders Rural Services

Tips to abate mice threat to bumper harvest

Mice are back on the radar of grain growers ahead of spring.

Elders senior agronomist, Peter Eliott-Lockhart based in Geraldton Western Australia explains that numbers will continue to build over the next few months, threatening what is projected to be an exceptional harvest.

“We are monitoring mice numbers in cereal crops on the approach to spring and have commenced baiting in some areas,” says Peter.

“Although we have different environmental conditions compared to the eastern states, with hot summers and lower water availability over summer for mice, it is still important to look at the lessons learned from earlier outbreaks in the eastern states.”

It’s a timely reminder to revisit monitoring techniques to help determine if baiting is required, not just in Western Australia but across all states.

Quick tips

  • Start monitoring for mice now
  • Use a 50g/kg zinc phosphide bait
  • Don’t bait ahead of a significant rain event
  • Be prepared to make an early call to bait.

The rate of population growth can increase dramatically under ideal conditions. Controlling mouse populations during late winter and early spring will reduce the number of mice especially when breeding starts as temperatures increase.

Did you know?

  • 1 burrow can house 1 to 4 mice, and up to 40 mice.
  • Mice require 66 grains per day.
  • 1 kilogram of grain ≈ 330 mouse days of food.
  • 1 kilogram of bait per hectare = 3 grains per square metre.


In canola and legume crops, you should inspect flowers and pods for damage. At the first sign of crop damage be prepared to bait. Mice can also be active in cereal crops and will chew off the heads generally at the top node.

Mouse chew cards are an effective and simple way to monitor feeding levels in crop:

  • Select a few paddocks that are representative of the farm.
  • Soak the cards in canola oil and use wire pegs to pin them to the ground.
  • Chew cards should be placed at least 30m in the crop. Peg cards in a line 10m apart.
  • Check the cards for mouse damage the following morning.
    If >10 squares per card are eaten = low-moderate activity
    If >10 squares per card are eaten = moderate to high activity with possibility of some damage.
    If >20 squares per card are eaten = high to very high mouse activity, damage is likely, and an ongoing mouse problem is present.


The best chance of success is to bait before the milky stage or before pod development. Mice may not eat baits if high quality seeds or pods are available.

Bait with 50g/kg zinc phosphide* baits spread at 1kg/ha either via plane or spread.

The active ingredient loading of zinc phosphide baits has been increased from 25 to 50g/kg zinc oxide to increase death rate and reduce bait aversion or anti feeding behaviour. Mice feeding on lower strength baits have a 50 per cent mortality rate when ingested, whereas double strength baits will give a lethal dose every time. Double strength is also better in high density crops or in areas with damp mornings.

*Note: Please read and follow the product advice

Baiting tips:

  • Do not bait ahead of a significant forecast rain event. Ideally bait should be applied where there is a forecast for at least 3 to 4 dry days.
  • Do not mix mouse bait with urea. Zinc phosphide can be scraped off the surface of the treated grain when agitated with other substances.
  • Bait on the ground is more likely to be taken before mice climb plants to eat developing heads.
  • Coordinate baiting strategies with neighbours for area-wide management and highest impact.

We recommend you use the MouseAlert website to report sightings and update local data.

For information on federal and state based government support refer to the Australian government Department of Agriculture, Water and Environment website or download their Bait don’t wait fact sheet.

For specific local advice contact your local Elders agronomist.

Find your local branch
The information contained in this article is given for the purpose of providing general information only, and while Elders has exercised reasonable care, skill and diligence in its preparation, many factors (including environmental and seasonal) can impact its accuracy and currency. Accordingly, the information should not be relied upon under any circumstances and Elders assumes no liability for any loss consequently suffered. If you would like to speak to someone for tailored advice relating to any of the matters referred to in this article, please contact Elders.