Did you know that if there are high numbers of mice in your paddocks, they could cause up to 5% damage a night to your crop? Our current farming systems of no-till and stubble retention could be why we see high mice numbers each year. So how do you know what numbers are around and whether you should bait or not?

Getting a rough idea:

To get an idea of what is going on in paddocks, you can walk a transect of 100 metres across a paddock, counting active holes in a 1-metre wide strip. One burrow per walk would be equal to 100 burrows per hectare. However, be aware hole counts will vary by soil type. For example:
In sandy soils – mice may dig many holes in search of seeds, and these could look similar to nesting burrows.
In hard-setting soils – there may be fewer holes but may contain more mice per hole.
And in cracking soils, well, they can be hard to identify.

How to check mice activity levels:

One way you can check a hole’s activity by sprinkling some talcum powder around it and going back the following day to check the disturbance levels. 

Another way to test is using mouse chew cards. This is done by cutting some strong paper or light card into 10cm x 10cm squares, marked with a 1cm grid and soaked in canola or linseed oil. Then place the cards randomly across a paddock and peg them to the ground. If more than ten squares are eaten per card overnight, considerable mouse populations are emerging. If there are more than 20 squares per card eaten in immature crops, then there is a significant problem. 

Below are examples of how chew cards work and the activity levels in She-Oak Log, Saddleworth, and Agery from 2021. 

When to bait:

If mice levels are found to be high, we recommend spreading a zinc phosphide bait. The best practice is to bait at the time of sowing, or within 24 hours to protect the recently sowed crop. Mouse damage will be the most severe for about two to three weeks after crop emergence and again around seed-set. See us today for our range of mouse baits, chew cards, as well as traps and baits for around the house or any other information on monitoring mice levels and when to bait. Secure your product before things get tight.

6 Tips For Mice Free Paddocks:

1. Actively gauge numbers by going into the paddock.

2. Try to remove residual food. Baiting when there is as little food as possible is generally the best practice.

3. Bait six weeks out from sowing if pressure is excessive (as this allows enough time to overcome sub-lethal doses/aversion).

4. If mice are still present at sowing bait off the back of the planter to prevent damage to the freshly sown crop. 

5. Baiting at sowing is most effective if no other food sources are available.

6. Obviously, crop type will come into decision making when baiting. If unsure, call us to chat with an agronomist.

This was originally published on April 13th 2021 but has been updated and revamped for you to make sure it is accurate and relevant.