The voluntary ban on the use of metaldehyde slug pellets on high-risk fields is being extended to two further water catchments this September.

It means there will be four pilot areas in England where no metaldehyde can be applied to certain fields, as the industry steps up its efforts to prevent the active ingredient from entering water supplies.

From September 2014, growers in Thames Water’s Pincey Brook catchment in Hertfordshire and Anglia Water’s Pitsford catchment in Northamptonshire join those in the existing Mimmshill Brook and Avon & Leam catchments, all of whom are being encouraged to switch to alternative products where slug control is necessary.

On designated high risk fields – regardless of the crop being grown or the seasonal slug pressure – there’s a voluntary commitment to stop using metaldehyde altogether.

For growers with target fields in these areas, the slug pellet options are extremely limited. With methiocarb being withdrawn and final product sales ending on 18 September 2014 (use by September 2015), the only remaining active ingredient for those affected is ferric phosphate.

Sold under the brand names of Sluxx and Derrex, ferric phosphate is an effective alternative to metaldehyde and should be used in the same way as other molluscicides, but it has the added benefit of having no issues with buffer zones, harvest intervals and watercourses.

According to Robert Lidstone of manufacturer Certis, ferric phosphate works as a stomach poison on slugs, in a similar way to methiocarb.

“Slugs which have ingested ferric phosphate pellets stop feeding almost immediately,” he says. “Most importantly, that means crop damage stops, too.”

However, the slugs take a bit of time to die and go back underground before this process occurs. As a result, growers won’t see either the dead slugs or the slime trails that they are used to with metaldehyde, so they will need to adopt a different mindset.

“That’s a change to existing practice and it has been seen as an obstacle to the uptake of ferric phosphate in the past,” he acknowledges. “But as more farmers switch to ferric phosphate-based pellets, it will become the norm rather than the exception.”

Growers can use a maximum rate of 7kg/ha of Sluxx, which contains 3% ferric phosphate, he advises. “And there’s a maximum total dose of 28kg/ha per crop.”

With no risk to water supplies, Sluxx and Derrex can be applied in wet conditions and where drains are flowing, he adds. “There’s certainly more timing flexibility with it, as well as a better environmental profile.”

Sluxx pellets can be applied with existing application equipment and there are published machinery settings to ensure accuracy, ends Mr Lidstone.

That’s the joint message from Defra, the Environment Agency and the water companies ahead of the autumn, as they look to address any metaldehyde exceedances in drinking water while maintaining the availability of slug pellet products.

All three organisations are committed to working with the farming industry to find a more targeted, risk-based method of tackling the problem, they insist. Best practice advice, which has been in place since 2008, hasn’t made enough of a difference in all catchments.

As Simon Eyre of Anglian Water explains, the important of metaldehyde to farmers means that a UK wide ban would be a very last resort. “But we have an obligation to be compliant with drinking water standards, so we need to come up with some innovative solutions to address the problem.

“The pilot project, where zero metaldehyde is advocated in certain fields, is one example of this activity.”

Dr David Cameron, chairman of the Metaldehyde Stewardship Group (MSG), believes that the season ahead will be crucial.

“Ideally, we want the risks of metaldehyde movement to water being assessed on a field-by-field level,” he explains. “Remember that heavier, under drained soils are most affected.”

To find out if the land receiving slug pellets is at risk, growers can visit the Environment Agency’s WIYBY website, which will show if metaldehyde is an identified problem in the area, he adds.

“These risk factors can be summed up as the three Ss – slope, stream and soil type – where the field’s topography, proximity to a watercourse and soil type are the key issues.”

Metaldehyde alternative

Growers must take metaldehyde stewardship seriously. That’s the joint message from Defra, the Environment Agency and the water companies ahead of the autumn, as they look to address any metaldehyde exceedances in drinking water while maintaining the availability of slug pellet products.

All three organisations are committed to working with the farming industry to find a more targeted, risk-based method of tackling the problem, they insist. Best practice advice, which has been in place since 2008, hasnt made enough of a difference in all catchments.

As Simon Eyre of Anglian Water explains, the important of metaldehyde to farmers means that a UK wide ban would be a very last resort. But we have an obligation to be compliant with drinking water standards, so we need to come up with some innovative solutions to address the problem.

The pilot project, where zero metaldehyde is advocated in certain fields, is one example of this activity.Dr David Cameron, chairman of the Metaldehyde Stewardship Group (MSG), believes that the season ahead will be crucial.

Ideally, we want the risks of metaldehyde movement to water being assessed on a field-by-field level, he explains. Remember that heavier, under drained soils are most affected.

To find out if the land receiving slug pellets is at risk, growers can visit the Environment Agencys WIYBY website, which will show if metaldehyde is an identified problem in the area, he adds. These risk factors can be summed up as the three Ss slope, stream and soil type where the fields topography, proximity to a watercourse and soil type are the key issues.