WITH MICE numbers reaching plague proportions in some areas of Yorke Peninsula, particularly at Maitland, cereal growers are closely monitoring the pest as seeding nears.
Ben Wundersitz, who runs a 5500-hectare wheat, barley, canola and lentil farm at Maitland, has been undertaking baiting trials to monitor the success of zinc phosphide application at different rates.
"The tradition would normally have been to bait after seeding but I just didn't think that was an option with the amount of numbers we're seeing," he said.
"I've never seen numbers so big."
Ben baited one week after Invasive Animals Cooperative Research Centre contract scientist Julianne Farrell visited to estimate mouse populations.
Ms Farrell was commissioned to put out traps on six properties between Maitland and Balgowan to get an idea of the breeding status for mice and a rough estimate of the number of mice a hectare.
"She said it was the biggest population of mice she's ever seen - we're talking populations of up to 4000 a hectare," Ben said.
"She then came back and monitored after baiting and found that we've had good levels of control at the label rate of application."
Ben was picking mice up in the header during harvest, something he has never experienced before, and found them in barley windrows.
"I think there was a bit of grain wasted at harvest through wind and what-not, and last year was the first year we did not bait in four years," he said.
"There was a population there but it wasn't really economic to bait, and it's probably just carried through a bit under the radar.
"They started to breed-up around harvest and have bred ever since."
The early rains in February are also likely to have contributed to the population, because, while it took some of the pests' food source away at grain germination, it still provided mice with water.
"That early break meant there was a heap of green feed around," Ben said.
"They go out and eat all the plant matter and continue to get moisture, but then there's still grain in the paddock as well."
Ms Farrell said she was asked to return to monitor Ben's baiting trial to measure the effect of different application rates on the mice population.
"The label rate that's currently enforced for zinc phosphide is still effective, and applying it more than the label rate is still illegal and doesn't kill many more mice," she said.
McFarrell said the mice population was so high that it was necessary for farmers to reduce mouse numbers before seeding or they would dig up the freshly sown seed and reduce the potential yield.
"If they dig up too much then the grower has to go back and re-sow, which is very time consuming and expensive on their part," she said.
But despite reports of a mouse plague at Maitland - with houses being affected and Maitland Hospital transferring some patients to nearby hospitals as a precautionary measure - Ms Farrell said numbers were starting to drop a little.
"But it's not hapenning slowly enough to have negligible numbers at sowing time," she said.
"Based on the information I've got from growers and from trapping over the past two weeks, I'd be suggesting that growers bait prior to sowing and do some follow-up sowing if they think they need to."
* Full report in Stock Journal, April 17, 2014 issue.
