Growers warned of high risk of mouse damage at seeding
Southern region grain growers are being warned of the potential for substantial and widespread problems with mice at seeding this year.
Large starting populations of mice coupled with heavy 2010 crop yields and significant summer rain have created a high risk situation come sowing time.
Supported by the Grains Research and Development Corporation (GRDC), authorities advise that a second period of high crop damage could occur at flowering/seed-set in some areas where mouse numbers decline only during spring, rather than late winter.
Biosecurity SA’s – NRM Biosecurity senior research officer, Greg Mutze, says the worst hit areas from last year may be at less risk this year because, historically, severe mouse plagues have rarely occurred in the same area in consecutive years.
“That may be because mouse diseases become more prevalent and persist for a year or two, but if it relates to depletion of persistent seed sources, the historical precedent may no longer apply in current farming systems,” Mr Mutze warned.
Speaking at the recent GRDC Grains Research Update in Adelaide, Mr Mutze said preventing seed set on summer weeds was clearly a priority among the management options available to address the present issue.
“Other stubble management options that were considered to be effective last year need careful consideration for impact on soil stability,” he said. “If grazing is to be used as part of that process, it will be most effective to graze hard and early to remove leftover grain before mice have an opportunity to utilise it.”
Preliminary data from a landholder survey of mouse damage in 2010, undertaken by Mr Mutze, indicated that average yield losses of 30% occurred in those crops most affected by mice. “Grassy weeds have invaded some of the crops badly thinned by mice, so weed control costs will also be higher for some years,” he said.
The survey of 140 landholders revealed that baiting efficacy was improved by: baiting at or immediately after sowing, rather than four days to a week later; the use of registered zinc phosphide products at recommended rates; and effective summer weed control.
Mr Mutze said that beyond 2011, the costs of mouse damage in grain crops was likely to continue to rise if no-till, continuous-cropping, livestock-free farm systems became more prevalent, along with more extreme weather events.
“Reduced competition from livestock grazing in grain stubbles, more frequent cropping, stubble and trash retention and more diverse crops have increased the amount of grain available to mice, the time span over which high quality food is available, the amount of cover and prolonged the period of crops at vulnerable stages,” Mr Mutze said.
“Consequently, mouse numbers are now higher for any set of seasonal conditions and are reaching problematic levels more often than previously recorded, and are causing more damage for any given level of mouse infestation.”
Mr Mutze said more cost-effective baiting options may be able to address part of the problem, but at the core of the issue was the quantity of seed left in stubbles.
“Grain loss at harvest is the main determinant of subsequent mouse infestation and damage in autumn, and the extent of grain loss appears to be underestimated by many producers,” he said.
Mr Mutze said innovations such as the GRDC-funded Harrington Seed Destructor could assist in reducing mouse numbers by destroying the grain and weed seed source that goes through the harvester so it is not available for mice to eat in stubbles, as well reducing weeds which offered another source of food and cover through the summer and autumn.
The GRDC has developed a central source of information on mouse control via the website www.grdc.com.au/pestlinks.
An updated GRDC fact sheet on mouse management is also available via www.grdc.com.au/mouse_management or by contacting GRDC Ground Cover Direct, free phone 1800 110044 or email email@example.com.
The GRDC, on behalf of growers and the Australian Government, is making further investment in mouse control strategies in 2011 based on grower and advisor input to complement previous research projects conducted on this topic.
Caption: Greg Mutze from Biosecurity SA speaking at the GRDC research Update in Adelaide.
• Further information is available from Greg Mutze via firstname.lastname@example.org or (08) 8303 9505
• This media release and other media products are available via www.grdc.com.au/media
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