Yorkshire Water is calling on farmers on land near the rivers Derwent, Wiske and Ouse to manage the use of slug control pesticides carefully to reduce the impact they could have on tap water quality.
The pellets can occasionally leak into watercourses in Yorkshire’s farming heartlands. In particular, the River Derwent from West Ayton down to Barnby Marsh including all its tributaries, along with key tributaries of the River Ouse such as the River Wiske, Cod Beck and River Kyle.
An active ingredient in the pellets - metaldehyde - poses no danger to health but its levels in the River Derwent, Wiske and Ouse have occasionally breached UK drinking water standards in previous years.
In response, Yorkshire Water and partners including the National Farmers Union are encouraging farmers to adopt an Integrated Pest Management approach, with less reliance on metaldehyde slug pellets.
Andrew Walker, Catchment Strategy Manager at Yorkshire Water, said:
“We really appreciate the efforts farmers in Yorkshire are making to reduce the amount of metaldehyde getting into our rivers. These measures include switching to ferric phosphate-based pellets; adhering to the 10m buffer strips and implementing integrated pest management plans, and other cultivation techniques which can control slug populations without the need for chemicals.”
The Integrated Pest Management approach includes:
- sowing seeds deeper into the soil to prevent slugs reaching them
- rolling after seed drilling to consolidate the soil and make it harder for slugs to move about
- use of traps to assess slug numbers
- using ferric phosphate - a more environmentally friendly alternative to metaldehyde
Slug pellets are commonly used by farmers this time of the year to control slug infestations, which risk eating away at crops and damaging food production. The Metaldehyde Steward Group (MSG) has estimated that around 22% of land used for wheat growing is affected by slugs and necessitates the use of pellets.
Trials in some parts of the UK have shown that 98.7% of metaldehyde contamination within rivers and streams comes via flowing field drains.
However, the water company pointed out that despite the impact of metaldehyde, water quality compliance in Yorkshire remains excellent with 99.95% of hundreds of thousands of samples meeting tight regulatory standards in the last year.
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