Slug Pellet Pollution

I read in BW that metaldyhyde pollution in watercourses is a growing problem for water companies, and that this comes from slug pellets used by farmers to protect oilseed rape. Since oilseed rape is a Hope Farm crop, how is this issue handled?

  • Dear Martin,

    Thank you for your enquiry about slug control at Hope Farm.

    As I’m sure you know, Hope Farm is run as a conventional arable farm growing wheat, oilseed rape and field beans. By being run as a conventional arable farm we remain relevant to the vast majority of other arable farmers in the UK, and we hope to show that it is quite possible to integrate successful wildlife management with conventional farming without significantly impacting on the farm’s profitability. In doing so, we are best able to influence environmental land management on the 45% of farmland that is cropped.

    In doing this, a key aspect of the farm is growing as good quality and yielding crops as possible. Each crop requires a range of products to be used to protect the plants at all stages of development. Slug damage is significant in most years, and in extreme cases, can lead to the need to establish a new crop. This comes at considerable expense to the farmer.

    Here at Hope Farm, it is necessary to apply one application of slug pellets to our oilseed rape crops, which we have autocast oilseed rape into. Using the autocast method of establishment is better for the soil and wildlife, and saves time and cost in establishment. However, it creates a good covering of mulched straw across the field, which becomes an ideal habitat for slugs. Our independent agronomist checks the crops very regularly and advises whether additional applications of slug pellets are required. We do keep these applications to a minimum. Slugs can also be a problem in our winter wheat crops.

    This year has been very damp over a prolonged period and high numbers of slugs have been observed in wheat and oilseed rape crops. As a result, we have had to apply two applications of slug pellets to our oilseed rape crops and one to our wheat crops. Some farmers may have applied more if the crop required it.

    There are of course significant issues with some of the chemicals used in some brands of slug pellets, such as metaldehyde and methiocarb. Both can be extremely toxic to aquatic organisms, and you are quite correct that the water industry spends a considerable amount of money annually cleaning these chemicals out of the water for drinking. This is why we follow industry best practice guidelines here, ensuring that when we use slug pellets containing metaldehyde that there are not spread within 10m of any water course and not before any rain is expected. We also try to use another product where possible which doesn’t contain metaldehyde, but which can be effective at slug control called ferric phosphate. This is particularly useful near water courses. We do not use products containing methiocarb.

    Of course using toxic chemicals such as metaldehyde can cause problems to wildlife both in and off the fields. This is why we have developed a range of habitats around the farm, such as grass margins, flower rich margins, wild bird cover, ponds in ditches etc, to mitigate the impact of these chemicals at the farm scale. We have observed a staggering increase in both breeding and wintering bird populations here at the farm as I’m sure you know using these simple measures. Some of these habitats also encourage a degree of natural slug control through encouraging natural predators, such as beetles, to thrive. This is the essence of Hope Farm, showing that managing small areas of the farm well for wildlife can mitigate some of the impact of growing crops for food.

    Finally, as you seem very interested in Hope Farm and we are doing here can I invite you to visit the farm sometime in 2013 so I can show you what we do and have a good chat about all the pros and cons of conservation farming.

    Have a great Christmas and New Year,

    Ian Dillon, Hope Farm Manager.

  • Hi Ian,

    Thank you for your thorough explanation of how the impact of chemicals is mitigated at Hope Farm. I think that this information is important and hope that the internet is a good place to spread the news. Hope Farm shows how farmers can be wildlife friendly without having to go to the extreme of going organic, and still being profitable.

    Thanks for the invitation, I'll think about it, but it's a bit of a trek from here.

    Merry Christmas and Happy New Year,


  • Sue Everett of Conservation News at British Wildlife magazine tells me that metaldyhyde in water courses at very low levels (EU standard 1ppm) does not harm wildlife. It appears to be a drinking water problem. So I guess if it's only bad for people, that's ok then.

  • Drinking water standards for all pesticides are set at 1ppm – in essence this is a surrogate for zero that dates back 20-30 years. This reflects an inherently precautionary approach to human health protection. Since then technology has moved on and we can detect pesticides at vanishingly small concentrations but the standard remains unchanged.

    So are current concentrations a problem? Well, firstly we should consider that what we’ve learnt about metaldehyde suggests it last longer in the environment and is far more mobile than originally thought. This raises some interesting questions about the tests routinely applied when authorising a pesticide for use. How many other surprises await the environmental chemist in the future?

    As for toxicology – Pan-UK have a nice summary of studies that point to concerns for wildlife and pets but l I’m not acutely concerned about my tap water even though I know the source is surrounded by intensive arable crops. That said I’d rather not be drinking this stuff and I’d rather it wasn’t turning up in watercourses at concentrations well in excess of 1ppm.

    But what really bothers me is that Government has failed show any kind of strategic leadership on the issue. The farming industry has tried its best through education and advice but if it keeps turning up in drinking water, as I suspect it will, we risk sleep walking into a ban. I fear this will inevitably mean a mass switch to methiocarb  (a pesticide with significant risks to wildlife) because apparently safer alternatives based on ferric phosphate struggles to gain farmer acceptance against the marketing power of big agri-industry.

    So metaldehyde wouldn’t be the first concern for wildlife or even human health but the fact it is popping up all over the place does suggest the way we regulate and use pesticides is far from perfect.

    Rob Cunningham (Head of Water Policy)

  • Thanks, I can see a lot of interesting information.