The role of drain flow as the primary means of pesticides reaching watercourses was highlighted at a recent ‘Pesticides and Water Protection’ meeting hosted by Catchment Sensitive Farming (CSF) and the Voluntary Initiative (VI) in the West Midlands.
With metaldehyde now the most significant pesticide issue for water companies across England, the Metaldehyde Stewardship Group’s spokesman Dr Paul Fogg said that whilst surface run-off remains an important route to surface water; soil, drainage and weather are critical considerations.
He pointed to the highest risk scenario for metaldehyde as being when land is at full water holding capacity and when there is a combination of both drain flow and forecast rainfall. “Employing a buffer zone to mitigate against surface run-off, or treating with an alternative only around the headlands won’t prevent metaldehyde reaching a watercourse in this scenario,” he warned.
“In such situations of drains flowing and heavy rain forecast, the MSG guidelines are unchanged in advising that metaldehyde must not be applied. Seek an alternative,” he urged, noting that the threshold of pesticide detection in water is so low that every farmer and operator needs to beware.
He added that the issue is critical for those farming on land that falls into either a Drinking Water Protected Area (DrWPA) or the associated Safeguard Zone. “These represent the areas where water is abstracted by the water companies, or areas that feed into those abstraction points. Both are equally important.
“And it’s possible to find out if you fall into either of these areas by doing a simple postcode search of the Environment Agency’s online tool, ‘WIYBY’, or ‘What’s in Your Backyard’ by visiting www.wiyby.co.uk.
“If the postcode search highlights land within either a red area or a hatched black area that’s linked to a red DrWPA then it’s possible to find out if there is an identified risk of metaldehyde (and/or other pesticide) exceedance by double clicking on the red area,” noted Dr Fogg.
To request more information contact the MSG enquiry line on 0845 1770117.
High metaldehyde risk?
Metaldehyde Stewardship: Application guidelines
• Use minimum active per hectare to avoid drainage and runoff losses
• Maximum application rate 210g metaldehyde a.s./ha* For additional protection of water, BASIS qualified suppliers or advisors may recommend rates reduced to 160g a.s./ha or less*
• Maximum total dose from 1st August to 31st December: 210g metaldehyde a.s./ha* For additional protection of water, BASIS qualified suppliers or advisors may recommend rates reduced to 160g a.s./ha or less*
• Maximum total dose rate: 700g metaldehyde a.s./ha/ calendar year*
• No pellets to be applied within 6 metres of a watercourse
• Do not apply when heavy rain is forecast
• If drains are flowing do not apply metaldehyde based slug pellets
*from any combination of metaldehyde products
a.s active substance (or active ingredient)