Imagine seeing the first crop on your place for four years. Three or more years lost to drought - maybe you didn't plant in a couple of those years, at least saving the cost of seed and fertilizer. But this year you got decent rain and planted and the bank manager gave half a sigh of relief.
Now imagine that mice have also been at work. You may not have noticed them in big numbers but they are there, quietly damaging the crop. It may not be until the wheat heads look a bit white and unhealthy that you realise. There hasn't been much publicity; no one's talking up a mouse plague. But they are there and the damage might already be done.
This is the situation facing some grain producers in NSW and Queensland right now.
I've heard stories of some having the sudden realisation that their canola or wheat crop is under attack too late.
Mice plagues are nowadays largely considered a private matter. By that, I mean that there is little government or industry monitoring of mouse numbers going. The mice that damage a farmer's crop were born and bred on that property - they haven't come from somewhere else. The industry research body, the Grains R&D Corporation ensured that an in-crop product - MouseOff - was registered a few years ago and it is available through rural merchants. So It is really up to individual farmers to monitor their crop for mice and act accordingly.
Acting at the right time is vital.
Monitoring can be done simply by walking through a crop and counting active mouse holes in a 100 metre transect in a 1 metre wide strip. Five holes means there are 1,000 mice per hectare, enough to eat 5% of a freshly sown crop per night.
When holes can't be counted, canola-oil soaked paper 10 cm x 10 cm can be pinned out in the crop, 10 metres apart in three 100 metre transects. If 5% is eaten, mouse activity may be emerging. If 10% is eaten, immediate treatment is probably needed. Treatment for mice is relatively inexpensive compared with the current value of crops and is usually very effective.