Mice activity and control

Conducive conditions such as high stubble loads and lots of grain on the ground, particularly in barley paddocks, has meant an increase in mice numbers in recent months. 

Mice area April 2017

Source: GRDC Mouse monitoring project

Mice numbers in the Wimmera and Mallee region have been steadily increasing, however, according to MouseAlert mice numbers are considered moderate but have the potential to increase.

A mouse plague is defined when there is 800-1000 mice/ha, and in March 2017, there were 30-50 mice per hectare in Walpeup.

Monitoring mice population numbers is the first step to prevent plague numbers, and taking action as soon as it is required. Below are some steps to determine mice numbers on your property:

  • Create a transect to look for active burrows by walking 30m in from your fence line, then set a 100m by 1m transect through the crop (by following the furrows).
  • Walk along the transect and count any active burrows in your 100m transect. Identify fresh scratching, little piles of grain or mouse walk ways. Do this for 2-4 more transects across the paddock.
  • If you found 2-3 active burrows in the 100m, action is required.

You can also monitor mice activity using mouse chew cards.  

Once numbers have been determined, thorough control is imperative. Zinc phosphide (MouseOff®) is used for in-crop control. Each zinc phosphide treated grain has the potential to kill 20-30 mice. Once ingested it hits moisture in the gut and the gas is released causing death. If you have a low alternative food source and the mice numbers are not too high, it may be possible to treat with a 0.5kg/ha which will reduce costs.

The following control measures can be actioned:

  • Spreading 1kg of bait/ha (approximately 3 grains/m2, dependent on bait weight) will be sufficient to kill 10,000 mice/ha (reduce mice numbers by 95%).
  • Applying baits six weeks before sowing, only if when monitoring you found three active burrows in 100m transect.
  • Re-assess mice numbers four to six weeks before sowing to see if another bait is warranted. This additional bait will capture the mice whom before had an aversion to the bait and to target more susceptible mice.
  • If you choose to bait at the time of sowing, it is important to bait after sowing. Mice activity will increase after sowing due to soil disturbance, if you bait more than 24 hours after sowing it will not be as effective. Mice will eat bait on soil surface before they actively dig up sown seed.

Check the forecast prior to application to ensure there is no rain coming to maximise the effectiveness of the application. MouseOff® is available on steralised grain (125kg is $850+GST*), or non-steralised grain (MouseOff® Econobait 125kg is $585+GST*) with pest and disease declarations.

Always monitor and continue to do so even if you find low numbers. Being proactive is imperative with mice, let’s avoid a repeat of 2011. For further information mouse alert provides easy to understand information on all aspects of mice management, recording and reporting.

*Prices correct as of 24 April 2017

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