Caution urged with metaldehyde

Farmers looking either to apply metaldehyde slug pellets or make repeat applications this season, are being encouraged to act with caution.

Recent data from the water companies is again revealing that the active has been detected in raw water above the statutory 0.1µg/l limit set for treated drinking water.

“Instigated by widespread heavy rainfall in early October, a number of areas nationwide have seen peaks in the detection of metaldehyde,” says Dr Jim Marshall, Water UK policy and business adviser.

“However, following a week of much drier weather, levels have dropped significantly, and reduced metaldehyde exceedances have been reported.

“I’d also like to add that generally these exceedances have been confined to streams and rivers,” he says.

Simon McMunn, of the Metaldehyde Stewardship Group (MSG), explains that the correlation between rainfall and exceedances is a clear one. However, farmers need to remain vigilant at all times when applying slug pellets.

“Slug pressure remains high, and with many late sown first wheat and second wheat crops in particular remaining at risk from slug attack, further metaldehyde treatments should be carefully assessed,” says Mr McMunn.

“What’s more, given the recent level of detections, it’s important to consider the field risk factors,” adds Mr McMunn.

“A field’s soil type, topography, presence of artificial drainage and its proximity to water are key to whether metaldehyde could be a risk to a watercourse that will subsequently be abstracted for drinking water.

“It’s also important to ensure no metaldehyde treatments are made when drains are flowing and heavy rain is forecast - the MSG guidelines are unchanged in stating this.

“It’s imperative that we work hard to prevent exceedances of metaldehyde in water to help secure a future for this active and retain slug control choice. Visit and enter the relevant postcode to find out if there is a metaldehyde risk in the area.”

Dr Marshall adds that the joint approach by the agricultural and water sectors over the past few years has seen marked improvement in reducing the concentrations of metaldehyde in watercourses.

“What’s more, I believe that by continuing to adopt good practice in applications, it should be possible to manage the risks posed by metaldehyde.”

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