During the autumn and winter of 2021, mice caused an increase in crop damage across the WA grainbelt. The conducive conditions meant that plagues could occur quickly, with high-yielding crops providing a large food source.

To avoid worst-case scenarios, the National Grower Network (NGN) helped to launch a mouse surveillance program across five agricultural zones in WA: Geraldton, Albany, Esperance, Kwinana West and Kwinana East. The project is led by FARMANCO.

Surveillance data was obtained from 10 sites within each zone during 2022 using a CSIRO protocol that uses white powder sprinkled at burrow entrances to reveal mouse activity, along with the use of bait cards. Monitoring at the 50 sites occurred at pre-seeding, post-seeding, mid-season and pre-harvest.

This data was used to estimate the number of mice per hectare. This was fed back to GRDC, which produced heat maps depicting mice numbers. The colour code assumes economic damage occurs at numbers greater than 200 mice per hectare. Plague densities are 800 to 1000 mice/ha.

These maps can be viewed at the Mouse Alert site.

At a certain threshold of mouse activity, the tracking program triggered alerts to growers and advisers to check paddocks and consider baiting with zinc phosphide to keep mouse populations low.

Additionally, the monitoring team provided extension services on effective baiting strategies, including workshops in affected areas, to ensure that lethal doses of zinc phosphide bait were delivered. This included assistance with bait choice and application. Some key messages include:

• a preference for 50 gram per kilogram zinc phosphide baits over 25g/kg;
• an application rate of 1kg/ha;
• apply at night or early evening to maximise bait consumption;
• avoid applying on wet soils (or when rain is forecast) as baits will deteriorate when in contact with water;
• avoid spreading with other products; and
• assessing risk with the benchmark that phosphide treatment at 1kg/ha (20,000 lethal doses/ha) should give control of greater than 90 per cent.

With WA producing a record-breaking grain delivery in 2022 and mouse activity detected early in the season, the monitoring work detected high populations and signs that plague conditions were building. Despite the conducive conditions, plagues were avoided.

The surveillance work has been extended into 2023-24, with 10 additional sites added to the monitoring protocol.

Another change has growers taking over the surveillance work at the monitoring sites, thereby embedding the early detection alerts in the farming system into the future.

This project complements existing CSIRO/GRDC investment CSP1806-017RTX and was undertaken in consultation with CSIRO’s Steve Henry.

More information: Blake O'Meagher, [email protected]

Bait  spreading trials

By Ben White, Kondinin Group

The spread patterns produced by various mouse bait-spreading methods and devices are the subject of a National Grower Network project now underway.

A research engineering team led by Ben White (in consultation with CSIRO’s Steve Henry) aims to test several bait application systems and identify best-practice standards. The project will include ground systems – such as mouse-specific and adapted spreaders – as well as aerial spread via fixed and rotary wing aircraft.

The project will address the key spreading constraint – the need to achieve uniform spread at a low rate of just three baited grains per square metre (equivalent to 1kg per hectare).

The trials will deploy custom-built equipment to measure spread patterns. Three such measurement systems will undergo comparisons: the use of fluorescent bait and black light; trays with baffles; and the use of low-bounce ground sheets to capture the spread bait.

The best-performing option will then be used to collect data, with Statistics for the Australian Grains Industry (SAGI) assisting in the development of a test protocol. The project will then attempt to develop bait spreading protocols and distribution uniformity benchmarks that are as reliable as those for other granular products, such as fertiliser and lime.

The project will also visit growers who have successfully used innovative bait spreading practices to produce 15 case studies – five each in the GRDC northern, southern and western regions.

Videos of different mouse baiting options can be viewed here:

More information: Ben White, [email protected]