WHILE the drought has kept mice numbers low, croppers should not be complacent, according to CSIRO researcher Steve Henry.
Mr Henry gave a presentation on 2018 mouse numbers, baiting methods and the forecast for this season at the GRDC Grains Research Update in Adelaide last week.
He said farmer reports of the “occasional active burrow” was of concern because of the potential for rapid mouse population increase.
Last season, Mr Henry said mice numbers were kept low, due to good baiting early in the season, the dry autumn and then really cold weather.
“But now is not the time to be complacent," he said.
“Farmers need to be out checking for active burrows because if conditions become favourable for mice, the rate of increase could lead to significant changes in mouse populations.”
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Mr Henry outlined recent research outcomes and programs under way to better manage mice, including a remote monitoring system to increase research sites, investigate how mice were making better use of no-till cropping systems and the most effective forms of bait.
“Mice no longer live on the outskirts of paddocks, they are living in undisturbed warrens within the paddock,” he said.
“When farmers used to cultivate to control weeds, zinc phosphide was more effective as residual grains were buried by the cultivation and the first thing mice would find on the surface was the bait, so high knockdowns were achieved.
“Today, our research has come about because farmers are reporting that zinc phosphide is less effective than it was in the past.”
Mr Henry said recent research looked at the preferred feed sources of mice, including malt barley, durum wheat and lentils.
“This research highlighted that mice had a strong preference for cereals ahead of lentils,” he said.
“This means that lentils are a poor candidate for an alternative bait substrate."
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Mr Henry said that some mice in the lab trial ate zinc phosphide on grain and didn’t die.
"A key finding of the work in the lab was that mice that ate bait and didn’t die became bait averse very quickly," he said.
“So for croppers putting out zinc phosphide and not getting a good result, there’s no point in putting out another application immediately but instead should wait for mice to forget their aversion prior to applying bait again."
Mr Henry also advised growers to try to reduce background food in a paddock before bait application to enhance uptake of the baited grain.
