Arable farmers are being urged to follow Metaldehyde Stewardship Group (MSG) guidelines closely to avoid polluting water in the product’s last season of use.

There is uncertainty about exactly how much product remains on farm to use up following the slug pellet’s loss of authorisation.

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No further supplies are being manufactured for the UK market, but distributor stocks can be sold and used up until 31 March 2022.

On-farm stocks

Richard Reynolds, senior agronomy adviser for Anglian Water and the Water UK catchment network representative on the Voluntary Initiative, says feedback from agronomists, farmers and distribution suggests 40-60% of farms have some stocks of metaldehyde.

“But what we don’t know is whether that is one bag or one pallet on each farm,” he says.

In a worst-case scenario that could lead to significant spikes of metaldehyde in water supplies, which the water companies are unable to remove through raw water treatment.

The challenge is that this is the last year for it to be used legally. Farmers face the choice of using it or paying to get rid of it, so there is little incentive to not use remaining stocks, Mr Reynolds says.

“But metaldehyde really matters this season, and we need the agricultural community’s help in getting it right. If you don’t have to use it, please don’t,” he says, urging farmers to follow the MSG’s guidance.

Most growers are likely have both metaldehyde and ferric phosphate available, so remember best practice when deciding where and which to use.

“Keep the buffer areas and use metaldehyde in the middle of the field rather than the edge,” he says. “Ultimately, metaldehyde only becomes a problem for the water industry when it leaves the field.”

Integrated approach

Metaldehyde slug pellets must only be used as part of a wider integrated pest management programme, stresses David Cameron, the MSG chairman. “That helps minimise slug infestations and reduces the need for treatment,” he says.

“Factors such as soil and stubble management, planting methods, weather, trapping and monitoring should all be considered as part of slug control programmes.”

Growers should also take a field-by-field approach to assess the risk of metaldehyde reaching watercourses, Dr Cameron says.

“Think ‘soil, slope and stream’. Your field’s soil type, topography and proximity to a watercourse are all key to understanding whether applications could impact drinking water quality.”