According to the Grains Research and Development Corporation (GRDC), mouse activity is on the rise across both states, due to ample food and cover as a result of last year’s bumper harvest.

CSIRO researcher Steve Henry has been surveying mouse activity for a GRDC-funded project, and he said mouse abundance was increasing on South Australia’s northern Adelaide Plains, Yorke and Eyre Peninsulas, and in areas along Victoria’s grain belt.

With mice continuing to breed, Henry said populations were set to rise further in the lead-up to sowing of this year’s winter crops.

“Growers should remain vigilant and act accordingly if damage is likely,” Henry said.

In observing unexplained variability in mouse activity from one paddock to the next on some properties, Henry said growers needed to monitor across multiple paddocks to get a true indication of numbers to inform their management decisions.

He recommends growers look for evidence of active burrows, rather than relying on mouse chew cards as these are not as effective when abundant alternative food is present.

“To look for active burrows, I suggest farmers walk about 30 metres in from the edge of the paddock and set a 100 metre (1 metre wide) transect through a crop, following the furrows,” Henry said.

“They should walk slowly along the transect scanning for evidence of mouse burrows, taking note of any burrow that looks active and recording the number of burrows per 100 metre transect, and then repeat across two or four transects.

“If there are more than two to three active burrows per 100 metres, then they have a mouse problem.”

Corn flour can be used also, while growers and advisers can report and map mouse presence, absence and level of activity using MouseAlert so others can see the scale and extent of localised mouse activity.