Grain growers in Victoria and South Australia in particular, and other parts for that matter should be prepared for a potential issue with mice in spring this year.
The latest reports from the Grains Research and Development Corporation’s (GRDC) regular mouse monitoring program investment indicate that mouse populations remain at moderate levels, for this time of year, in grain-growing regions across both States.
While mouse numbers are expected to decline over the remainder of winter, particularly if conditions are cold and wet, there is concern amongst scientists monitoring the situation that the sizeable background population and potential stored food reserves will enable a rapid increase in numbers when breeding recommences in spring.
To prepare for such a potential scenario, growers are being advised by the GRDC-supported National Mouse Management Working Group to continue actively monitoring mouse activity and look for signs of mouse damage, such as chewed tillers and nodes.
If mouse populations are high (more than 200 mice/hectare, when they cause economic damage), growers should consider baiting now before crops flower, as flowering crops are highly vulnerable to damage from mice.
If mouse populations are low (10-20 mice/ha) to moderate (50-100 mice/ha), growers should remain vigilant until the start of spring. Trapping in June near Mallala SA revealed densities of 30-50 mice/ha, and at Walpeup Vic densities were 30-60 mice/ha.
Growers are encouraged to communicate with their local bait supplier to be informed of supply timeframes and to determine whether pre-purchasing of bait is required. Crops cannot be treated with bait within 14 days of commencement of harvesting.
CSIRO researcher Steve Henry, who has just completed another round of surveying mouse activity for the GRDC investment, says vigilance over the coming weeks is critical as crops cannot compensate for heavy damage should it occur.
“If numbers build up significantly over spring, crops could be at serious risk of damage and the problem could continue after harvest and ahead of sowing next year’s crops,” Mr Henry says. “Even if growers don’t think they have a mouse problem, they should continue to monitor for activity through winter.”