SOUTHERN Australian grain producers continue to face rising mouse numbers, with farmers in pockets of South Australia and Victoria confronted with paddocks with mouse populations enough to cause significant damage to newly sown crop.
The mouse problem is sporadic, with chairman of the National Mouse Management Working Group (NMMWG), Ouyen, Victoria farmer Ian Hastings saying the problem varied markedly, not just from district to district, but from paddock to paddock.
“Overall, we are a long way short of mouse numbers reaching plague proportions, but certainly in some paddocks they are at economically damaging levels.”
Reports from parts of the Wimmera, in Victoria, indicate a sudden spike in mouse activity, with people reporting up to 20 mice captured in household traps a night.
Steve Henry, researcher with the NMMWG, said the definition of a mouse plague was somewhat rubbery.
“There is no formal figure on what constitutes a plague, it could be from 500 mice a hectare up to 1000.
“I think the more pertinent figure, rather than getting hung up on whether it is technically a plague or not, is the 200 mice a hectare that is the threshold for economic damage if left untreated.”
Mr Hastings said the problem was especially bad in South Australia’s Eyre Peninsula and Mid North regions and in the Wimmera.
Wimmera farmer Vaughn Maroske, Vectis, west of Horsham, said mouse numbers on his property were at high levels.
“We have been noticing them for a while, there was a big harvest last year, with plenty of grain on the ground, good stubble cover for them to live in and a mild summer so it is no real surprise to see numbers on the rise.”
He said there were a large number of burrows visible in paddocks and said he would likely bait to ensure newly sown crop was not damaged.
Claire Browne, researcher with Birchip Cropping Group (BCG) said mouse numbers a concern for many croppers in northern Victoria.
“It is something people are aware of, overall people are noticing high numbers in places, generally in cereal stubbles.”
Mr Henry said overall feedback was that the problem was worst in barley stubbles.
“A lot of barley grain was spilt out either prior to harvest or at harvest so that has provided a very good food source for mice.”
Darren Arney, chief executive of Grain Producers South Australia, said many farmers had already put out mouse bait and were planning to bait close to sowing.
“The numbers are definitely there, but people are aware of it and are baiting early.”
“Many people have been surprised by the extent of the problem, they have said they did not think they had many mice but then after burning they noticed there were significant numbers about.”
He said with registered baiting stations authorized by the South Australia government, farmers in the State had ample access to mouse bait this season.
“Supply should not be a problem.”
Mr Henry said numbers were high in parts of the Riverina also.
“There are problems around rice producing areas, which will be a problem given withholding period requirements.”
He said there were no meaningful numbers of mice from central NSW north.
“It got very wet in those areas in September and it probably prevented numbers building up.”
He said there were differences between types of mouse plagues.
“Sometimes you can see a single season with a sudden eruption of numbers, others you can see a more gradual increase with the mouse numbers becoming a problem the second season or the following spring, which could be the case with this event, particularly with the mild and wet autumn.”