Grain growers in South Australia and Victoria are being urged to assess current mouse numbers on their properties to determine if mice are likely to pose a risk at sowing.
If mouse numbers are a concern, growers should consult with their bait suppliers as soon as possible to ensure they have access to sufficient quantities of bait in advance of sowing.
Growers and their advisers attending Grains Research and Development Corporation (GRDC) Grains Research Updates in both States have been encouraged to be pro-active with mouse control strategies in 2018 in the wake of extensive crop damage in 2017 and a carryover of base populations through summer.
Mild weather and a reasonable supply of food sources as a result of grain being left on the ground due to weather events and frost in 2017 have contributed to numbers being at higher than normal levels.
Mouse monitoring experts engaged in GRDC research investments say potential therefore exists for economic damage at sowing in 2018 in parts of SA and Victoria.
CSIRO researcher Steve Henry says it is imperative that growers “get out of their vehicles, walk into their paddocks and get a good feel for what is going on” in respect to current numbers and activity.
“If they think they are going to need bait, they should talk to their suppliers immediately,” says Mr Henry. “If they leave it too late, supplies may not be available when they need to bait, as has occurred in previous years.
“Growers should be prepared to bait in the lead up to sowing, as well as being prepared to bait at sowing. And it is important that they monitor the effectiveness of baiting after each application.”
Broadscale application of zinc phosphide bait is the only method available to growers to control mice in their paddocks.
Mr Henry says timely application of bait at the prescribed rate (one kilogram per hectare) is paramount for reducing the impact that mice have on crops at sowing.
“Strategic use of bait is more effective than frequent use of bait. Ideally, bait should be applied eight weeks ahead of sowing, before another single application at sowing.”
Mr Henry also encourages growers to implement other mouse reduction strategies such as reducing the amount food sources available by spraying out summer weeds and volunteer cereals, and cleaning up grain on the ground by grazing sheep on stubbles (if feasible).
“Growers need to reduce alternative food sources to make baiting as effective as possible because bait aversion can be a real issue.”
Mr Henry and his CSIRO colleague Peter Brown have delivered some sobering mouse reproduction facts to growers and advisers attending GRDC Grains Research Updates, including:
- Mice start breeding at six weeks of age
- Litters of up to 10 pups are born every 20 days
- Female mice become pregnant again immediately after giving birth
- A single pair can give rise to 500 offspring in a season.
The threshold for economic damage at sowing is 200 mice/hectare.
Mr Henry encourages growers and advisers to continue to report and map mouse presence, absence and level of activity using MouseAlert so others can see the scale and extent of localised mouse activity.
MouseAlert also provides access to fact sheets about mouse control and forecasts of the likelihood for future high levels of mouse activity in each grain-growing region.
Despite considerable past and present investment ($6.9 million) in mouse-related research, development and extension (RD&E), the GRDC recognises that mice continue to be a key constraint across the southern cropping region.
Studies have included searching for new tools and active ingredients, bait application strategies and ongoing monitoring and surveillance. Further investment in mouse-related RD&E is being undertaken to provide growers with new management tools and strategies for mouse management in the future.