Grain growers planning to bait mice at seeding and through the growing season are encouraged to pay particular attention to the set-up and performance of their equipment to ensure optimum baiting impact.

Experts supported by the Grains Research and Development Corporation (GRDC) say while a number of different approaches to spreading mouse bait are available to growers, in all instances it is critical that equipment is calibrated to deliver bait at the required label rate to enhance success.

Zinc phosphide-coated bait must be applied at one kilogram per hectare across the paddock, excluding a 50 metre buffer zone to the edge of the crop and any native vegetation. One kg/ha equates to around two to three bait seeds per square metre.

Distribution should be as uniform as practical but the key is ensuring swaths no larger than 12 metres are unbaited. Because mice will move around the paddock to feed, they will inevitably pick up bait if this guideline is adhered to.

To assist growers with their mouse baiting programs, the GRDC has made new resources available for viewing at www.grdc.com.au/mousecontrol and via the GRDC YouTube channel at goo.gl/75e4Vz. The practical tips and guidance, including videos, feature advice from agricultural engineer, Ben White.

Mr White says bait can be applied via a number of mechanisms, including air commodity carts, 12-volt broadcast spreaders, conventional linkage and trailing machines and bespoke innovations.

Air commodity cart: “If growers opt to spread mouse bait at the time of seeding, they can use the small seeds box or small seed meter rollers of their air commodity cart for metering the bait, and dedicated air line for distribution,” Mr White says. “This ensures the uniformity of seed and fertiliser across the seeding bar is not impacted.

“The small seeds box or small seed meter rollers are often used because the bait application rate of 1kg/ha is low. Dispersion of bait using this method is usually via secondary air lines on to dispersion plates at the back of the bar, which, depending on mounting height, spread the bait uniformly over a series of two to three metre bands across the width of the seeding bar.

“Alternatively, for tow-behind air cart configurations, growers have fitted custom plumbing to redirect the air flow and distribution spouts to blow the metered bait out across a working swath.”

12-volt systems: Using a single spinner attached to a 12-volt motor, Mr White says 12-volt broadcast spreaders can be mounted to a vehicle, quad-bike or tractor. Hopper capacity is between 30 and 100 litres with a single spinner powered by a 12-volt motor.

“Typically spreading mouse bait to about 24 metres, the 12-volt broadcast spreaders use a choke to adjust the flow of bait onto the spinner. While some designs use the spinner rotation to meter bait through the choke, others have a choke shut-off so the spinner can continue to rotate and a door starts or stops the flow of bait to the spinner.”

Conventional spreaders: Mr White says linkage and trailing spreaders can also be used to spread mouse bait. Because these spreaders usually involve two large spinner discs, bait can be spread to around 36 metres.

“The primary challenge with using these larger spreaders is achieving the very low baiting rate of 1kg/ha,” he says. “Some linkage and trailing spreaders with scales and computer-controlled metering chokes have settings for small seeds which may deliver a 1kg/ha rate.

“Belt-style spreaders may require a very low door setting and slow belt speeds to achieve 1kg/ha and some models may require the metering door width to be modified. A piece of stiff rubber fixed to the metering door with slots cut in it can be used to choke down the width of metered product.”

Farmer innovations: Innovative growers have also built and modified equipment for spreading mouse bait, according to Mr White. “These include using conventional belt spreaders to carry a mouse bait hopper in the bin with other product. The bait hopper is fitted with a separate metering door and bait spreader plates, allowing bait to be spread concurrently and thereby saving a working pass.”

Safety: Mr White reminds growers and bait application operators to wear appropriate Personal Protective Equipment (PPE) when baiting with zinc phosphide.

“Wear elbow length PVC gloves and a full face respirator, ensuring the respirator has a combined dust and gas cartridge, including a ‘B’ category. This is particularly important when opening the drum of bait as high concentrations of phosphine gas can be released – and always open the drum in a well-ventilated area to allow gasses to disperse.”

GRDC investment: Meanwhile, researchers have embarked on Australia’s largest investment into mouse-related research in the grains industry. The GRDC recently announced it is injecting more than $4.1 million into mouse control research, development and extension initiatives in response to the increasing prevalence of mice in many key grain-growing regions of Australia.

The new initiative includes three key investments which will be led by CSIRO. The first investment of more than $3.2 million focuses on understanding mouse ecology, biology and management, the second on increasing surveillance, and the third on mouse feeding preferences.

To further support growers with their mouse management strategies, the GRDC GrowNotes™ Better Mouse Management Tips and Tactics fact sheet and other useful resources are available via www.grdc.com.au/mousecontrol.

Growers and advisers are encouraged to continue to report and map mouse presence, absence and level of activity using MouseAlert (www.mousealert.org.au) so others can see the scale and extent of localised mouse activity.