Grain growers are being urged to assess current mouse numbers on their properties to determine if mice are likely to pose a risk at sowing, although numbers in the Ceduna region do not appear to be a major concern.
Growers and their advisers attending the recent Grains Research and Development Corporation (GRDC) Grains Research Update were encouraged to be pro-active with mouse control strategies in 2018 in the wake of extensive crop damage last year 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 for this time of year across South Australia and Victoria.
Mouse monitoring experts engaged in GRDC research investments said potential exists for economic damage at sowing this year in both states.
CSIRO researcher Steve Henry said it was imperative for growers to get out of their vehicles and walk into their paddocks to get a feel for what was happening in respect to current numbers.
“If they think they are going to need bait, they should talk to their suppliers immediately,” he said.
“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.”
Sales and development manager at WCT Rural Ceduna David Stott said he had not heard of major issues in the region at present.
“There doesn’t seem to be too many around at the minute from what I can gather,” he said.
“There is always some concern, but with a long dry summer it would have helped to reduce numbers.
“If they are not a problem then people don’t tend to deal with them and only bait when necessary.”
Broadscale application of zinc phosphide bait is the only method available to growers to control mice in their paddocks.
Mr Henry said timely application of bait at the prescribed rate of one kilogram per hectare was paramount for reducing the impact 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 encouraged growers to implement other mouse reduction strategies such as reducing the amount of food sources available by spraying out summer weeds and volunteer cereals, and cleaning up grain on the ground by grazing sheep on stubbles.
“Growers need to reduce alternative food sources to make baiting as effective as possible because bait aversion can be a real issue.”
Mice start breeding at six weeks of age and litters of up to 10 pups are born every 20 days, while female mice become pregnant again immediately after giving birth which means 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 encouraged growers and advisers to continue to report and map mouse presence, absence and level of activity using www.mousealert.org.au so others can see the scale and extent of localised mouse activity.