Sandy’s Garden ... Slugs and Methaldehyde

Sandy Simpson
Sandy Simpson

In all the years during which I have been penning this column, I don’t think I have ever begun with a quotation from Michael Gove.

Mr Gove is politician who is high up on the list of Public Enemies or the list of Guardians of Democracy according to one’s perception of the way forward as the United Kingdom near Brexit Day: but here he is on the website speaking about an impending ban on the chemical metaldehyde: “I recognise that significant effort has been put into encouraging growers and gardeners to use this pesticide responsibly by the Metaldehyde Stewardship Group.

However, the advice is clear that the risks to wildlife are simply too great – and we must all play our part in helping to protect the environment. I encourage companies and growers to look at the alternatives, such as ferric phosphate, which is authorised and does not carry similar risks.”

Of course, he is not referring directly to any outcomes of the Brexit process, but is here speaking as the Right Honourable Michael Gove MP, Secretary of State for Environment, Food and Rural Affairs (DEFRA) a post to which he was appointed on 11 June 2017. And setting aside the proprieties of DEFRA seemingly dealing with matters devolved to the Scottish Government, the Agriculture and Rural Economy Directorate of the Scottish Government recognised a growing problem … sorry about the pun … in a report published in 2017, wherein we find that, ‘The use of the molluscicide metaldehyde in Scottish agriculture increased by 96 per cent by area treated and 112 per cent by weight applied between 2014 and 2016. This could be partly due to changes in authorisation for molluscicides. All products containing methiocarb were withdrawn from use on 19th September 2015, therefore the use of metaldehyde and ferric phosphate increased.’

You will already know, gentle reader, that a mollusc is, to quote Collins Dictionary, ‘an animal such as a snail, clam, or octopus which has a soft body. Many types of mollusc have hard shells to protect them.’ And the mollusc in question here is that bane of many a farmer’s life, and that of many a gardener – the slug. If you have a garden, you probably have a slug killer based on metaldehyde in your shed or your greenhouse … hopefully well out of the reach of children and securely sealed in its original container … for pellets of grain treated with metaldehyde have been the most common form of slug control for many years. The grain attracts the slug; and the metaldehyde damages its mucus cells, causing the creature to produce masses of slime and dehydrate. Slugs which are not killed outright are immobilised, preventing them from returning to the protection of their usual daytime shelters.

O.K., so it’s not a nice death. But not many people will care unduly about that. The real reason for the upcoming ban on the outdoor use of metaldehyde is that we … gardeners … typically scatter many times the number of pellets which are required to deal with our garden slugs; and farmers, too, have been known to apply far more than the manufacturers recommend. Some of the metaldehyde-stricken slugs are eaten by other forms of wildlife … hedgehogs, newts, toads and some birds, such as song thrushes … which ingest the metaldehyde. Small amounts don’t do them too much harm: but large amounts … ! And uneaten pellets dissolve in the rain and end up in watercourses and so in our domestic water supply. This is why the use of metaldehyde will be phased out over the 18 months to give growers time to adjust to other methods of slug control. It will be legal to sell metaldehyde products for outdoor use … who uses it indoors? ... for the next six months, with use of the products then allowed for a further 12 months. And after that, its use will be illegal.