Monitoring needed as mouse hot spots appear in crops

Grain growers have been warned to stay alert for mouse activity as mouse “hot spots” pop up during planting.

Grain growers have been warned to stay alert for mouse activity as mouse “hot spots” appear during the 2022 planting season.

CSIRO researcher Steve Henry said mouse populations in NSW and Victoria were “patchy” but outbreaks had been reported in some areas.

“Any paddocks where there has been significant amounts of food left behind after harvest or that sustained significant grain loss, those are the paddocks that seem to be sustaining populations of mice,” he said.

Considering high grain prices this year it was “worth taking the time to protect … freshly sown crops”, he said.

In NSW, there were patches of higher mouse populations in the south of the state, while in other parts of the state numbers were very low, he said. In Victoria, reports of mice were limited to specific paddocks and were not “widespread”, he said.

Reports out of central Queensland indicated there were some paddocks with “really high numbers” and there was a fairly consistent amount of bait being spread across South Australia, indicating active mouse populations, he said.

Meanwhile in Western Australia, farmers were preparing for the second consecutive year of high mouse populations, he said.

Mouse mansion- quite active so better to get chew cards out and assess need for bait pic.twitter.com/fxeHqCilJ2

— James Bee (@originalstinger) April 14, 2022

Areas affected by rain at harvest, where farmers harvested crops quickly, as well as areas affected by hail damage, were particularly badly affected by high mouse populations, he said.

“Our advice to farmers is to treat each paddock on a paddock by paddock basis … and keep monitoring,” he said.

CSIRO researcher Steve Henry.

“The advantage of a significant baiting effort in areas where mouse numbers are high in the autumn is that it pushes the numbers down as we go into winter. Breeding stops in the winter time and so if you go into winter with relatively low numbers, and you don’t have high levels of overwinter survival, next spring, if conditions are favourable, they’ll start breeding from a lower population base,” he said.

Mr Henry recommended growers opt for bait with 50 grams of zinc phosphide per kilogram of wheat over bait with 25 grams of zinc phosphide – a recommendation supported by CSIRO research due to be published this year.