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The current situation and pest reports

While some regions experienced issues with mice in 2010, this was generally limited and appears to have been overshadowed, to a large degree, by the locust situation. This year however, mice numbers have risen significantly and are affecting large parts of South Australia, Victoria, New South Wales and Queensland. Some regions are affected worse than others; even on a local scale certain paddocks appear to have high mice numbers whereas nearby or adjacent paddocks have very few. As a general rule, mice numbers are driven by an interaction of environmental conditions and individual landholder practices. The summer floods appear to have had little impact on mice populations that built up last year. Being highly mobile, mice can readily move to dry places during floods, and it is thought that only prolonged flooding will have an affect on numbers in the field.

Managing director of Animal Control Technologies Australia (ACTA), Professor Linton Staples says the current mouse situation is very dynamic, and at present appears to be escalating almost daily. Linton says this is the largest mouse problem he has observed in their 15 years of operation. ACTA are currently operating at full capacity to produce MouseOff® baits so that they continue to be available to landholders in the coming weeks and months. Enough bait has been produced to treat 600,000 hectares of crops and ACTA are preparing to produce enough bait to cover another million hectares if needed. According to Linton, the situation this year began 1-2 months earlier than anticipated, and may ultimately end up being 4 times the scale of the largest problem ACTA have previously faced (i.e. in the past 15 years). 

Agronomist, Hayden Lunn (Landmark), reports seeing large numbers of mice in recently harvested rice crops near Finley, in the Riverina district of New South Wales. Hayden says the mice were living in the banks and swimming out into the rice bay then climbing plants to eat seed in the rice heads. Some mice were seen swimming out more than 5 m from the banks. Hayden says there is a large amount of concern for newly sown crops in paddocks following rice because once the water is drained the entire paddocks are accessible to mice. Perimeter and whole paddock baiting is likely to be used in an attempt to avoid damage at crop establishment.

Agronomist, Andrew Parr (Howard Martin & Co.), reports finding large numbers of mice holes in banks surrounding rice crops near Berrigan, also in the Riverina district of New South Wales. In other paddocks, Andrew has found significant damage to canola cotyledons caused by mice feeding. Damage was most evident around mouse holes, and along tree lines, where cotyledons were significantly chewed or had been completely removed. We have also received reports of mice causing significant damage to emerging canola crops north west of Swan Hill, in the Mallee district of Victoria, and north east of Wagga Wagga, in the South West Slopes district of New South Wales. In some cases the damage has meant entire paddocks will need to be re-sown after baiting has been carried out.

For the past 12 months, the Victorian DPI has been undertaking monitoring of mice holes in several paddocks across western Victoria. Through this work the DPI have identified significant mouse activity throughout the central Mallee region. Even in paddocks with little vegetative cover where there were initially thought to be very few mice, high densities of active mice holes have been found concentrated around weeds, large thistles and clumps of grass.

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