SOUTH Australian grain producers have found double-strength mouse bait effective in combatting mice on farm, according to a survey of growers undertaken by Grain Producers SA.

Last year, Grain Producers Australia applied to the Australian Pesticides and Veterinary Medicines Authority for another extension of the permit, which was first approved in May 2021, at the height of the mouse plague, to provide access to ZP50 products containing 50g/kg of zinc phosphate.

This extension application, adjusted for minor use rather than the original emergency use purpose, was not approved, and the APVMA permit subsequently expired on 31 December 2023.

To better understand dealing with mice in high numbers and baiting on-farm, GPSA surveyed grain producers throughout March and April 2024, and received 148 responses.

The survey found that almost 80pc of grain producers had crop yields impacted by mice in the past two seasons.

Of all respondents, 64pc used ZP50 mouse bait under permit in 2023, with growers on average rating the chemical’s effectiveness as nine out of ten.

Conversely, 47pc of respondents found ZP25 to be effective in controlling mouse numbers.

These respondents rated the effectiveness of ZP25 as five out of ten on average.

GPSA chief executive officer Brad Perry said the survey demonstrated that when SA grain producers had access to the double-strength mouse bait, they found it extremely effective.

“According to the survey, South Australia grain producers that used the double-strength mouse bait under permit rated it as 90pc effective, compared to the single dose at only 50pc effective,” Mr Perry said.

“Feedback in the survey from some growers highlighted that mice numbers are breeding in areas outside of their farm and then re-infiltrating paddocks during seeding.”

Mr Perry said it was clear from the comments in the survey that producers believed the double-strength mouse bait was not only more effective than the ZP25, containing 25g/kg of zinc phosphate, but also more efficient.

“While mouse numbers are being reported as patchy across the state, many grain producers in the survey were concerned about timing of access to a stronger bait if numbers grew quickly.”

Mr Perry said GPSA understands the importance of respecting the independent process of the APVMA and maintaining the integrity of that system.

GPA is continuing to work with and respond to the APVMA to explore options to allow the permit to be extended so growers can access ZP50 products to help them control mice and protect their crops.

Source: Grain Producers SA