Tips for better use of slug pellets this autumn

The news that two small zero metaldehyde pilot catchments are being set up with the relevant water companies this autumn reflects the growing concern for slug pellet use and the levels of metaldehyde being detected in water.

It also suggests that a more targeted, or risk-based, approach to pellet use in problem areas could be the way forward, as the industry and regulators work together to seek a lasting solution to this annual problem and avoid an outright metaldehyde ban.

For many farmers and agronomists, the first signs of more stringent measures will come as no surprise. Last year’s very wet conditions and high slug populations saw extensive slug pellet use, with the resulting peaks of metaldehyde found in drinking water being higher and more widespread than ever.

“A greater number of water companies reported problems in 2012,” reveals Jim Marshall of Water UK. “The levels of metaldehyde in drinking water catchments were similar or higher than those seen back in 2008, when cross-industry work started to address the problem.”

Spikes of pesticides are difficult for water companies to deal with, he points out. “It’s not just metaldehyde which causes problems, there are other actives too. And although cleaning technologies are advancing, the current treatment options are all about reduction, not removal.”

Despite the higher number of exceedances found in 2012, the Metaldehyde Stewardship Group’s advice for this year is unchanged, with the familiar 210g/ha limit for a single application and maximum seasonal treatment from August through to the end of December, as well as the 700g/ha maximum total dose in a year, remaining in place.

But the group recognises that a more targeted approach will be necessary and is hoping that a phased introduction of measures, which will be based on the results from the pilot catchments, will be acceptable to all.

To kick-off this season, all growers should find out if water from their land is abstracted for drinking water, advises Paul Fogg of the MSG. “It’s easy to find out of you are in a Drinking Water Protected Area or an associated Safeguard Zone, which is the area upstream of the former. Simply use the Environment Agency’s online tool at” It will tell you if there’s a risk of metaldehyde exceedances occurring in surface water in your locality, he continues. “If you’re in a high risk area, there are three priority actions.”

Using the minimum amount of active per hectare, knowing when the risk is at its highest on the land and recognising when to stop applying metaldehyde-based pellets are essential, he stresses.

“These measures are relevant to all farmers, but are especially important in high risk areas.”

The two pilot catchments, which have been set up with Severn Trent Water and Affinity Water, are small areas deemed to be at high risk, due to their physical characteristics and proximity to water. The plan is that no metaldehyde will be applied at all during the course of the year, which is why they are being referred to as zero metaldehyde areas.

Subject to their results, there’s an intention to roll out targeted and appropriate metaldehyde usage in the 80 Drinking Water Protected Areas and their associated Safeguard Zones found in the UK.

“We’re hoping to identify the hotspots by working with the water industry. Where extra measures and more protection are needed, they will be implemented.”

That could mean applying less metaldehyde or switching to a different product, he suggests.

Andrew Crossley (c) Peter Hill

Good things can flow by having better partnerships with water firms

Having a good relationship with his local water company has helped Suffolk farm director Andrew Crossley adopt a more integrated approach to slug control and pellet use.

Losing 15% of last year’s winter oilseed rape crop at Thurlow Estate Farms helped to convince him that effective slug control carried out early in the season, based on the results of trapping and an understanding of the risk, is the best way of tackling the pest.

“Once you get oilseed rape past the 2-3 leaves stage, the danger has gone,” he points out.

He is expecting further pest issues on the 4,480ha estate this autumn and is planning to use low doses of metaldehyde pellets, as well as alternatives and cultural techniques. “There will be a legacy from 2012 – the problem won’t just disappear. And as much as three quarters of our cropping is open to slug attack.”

Suffolk and Essex Water has been proactive in sharing local information with farmers and revealing if any metaldehyde exceedances have occurred, he reports.

“It’s a very good way of keeping everyone informed. Working together has to be the way forward – there’s no appetite for a metaldehyde ban.”

In 2012, Thurlow Estate Farms switched to using ferric phosphate on all headlands, which represents 5% of the farmed area. Seed-beds are consolidated as much as possible and trapping is carried out early, to determine the risk. “Our agronomists are also looking for eggs at this stage, as well as slugs,” says Mr Crossley.

The focus is always on winter wheat and oilseed rape, he says. “We take a targeted approach. There’s no point in applying pellets where they’re not needed. We never have to treat after beans, for example. “

The estate is in a Safeguard Zone, so he is committed to the MSG guidelines and is also investigating alternative methods of pellet application. “In this year’s oilseed rape, we are placing the pellets behind the drill, in a band with the seed, rather than broadcasting them.

“The plan is to get the crop away in August. We’re using as low a dose as we dare – it’s equivalent to applying one bag of sugar per hectare.”

A stubble rake used on the chopped straw ahead of drilling oilseed rape is also providing a pelleting opportunity.

“We’re putting a pelleter on the front of the tractor, with the rake working behind it, so that we can get a low dose of pellets under the straw.

“There’s nothing else for the slugs to eat at this timing, so we get a kill before drilling.”

He is concerned that the loss of neonicotinoid seed treatments, which deter slugs, could hamper the farm’s concerted efforts to reduce metaldehyde use.

“We never had to apply as many pellets where Deter (clothianidin) dressings were used. So it would be a shame if we were prevented from making further progress.”

An alternative? Drilling on the green 

A technique being used in France to prevent grain maize crops being decimated by slugs could help growers to reduce their reliance on metaldehyde, believes independent soil consultant Steve Townsend.

Known as drilling on the green, it came to light when cover crop mixtures, which were already in place at drilling, proved very attractive to slugs and allowed the grain maize to establish without damage. “The concept is based on the theory slugs will carry on feeding on whatever is present first,” he says. “In this case, they continued with the cover crops.”

In the UK, it would involve leaving some volunteers, so that the slugs developed a taste for them ahead of drilling, he admits. “You then drill through the volunteers. The slugs aren’t interested in the emerging crop and the volunteers can be sprayed off once the danger has gone.”

Farmers who have previously done it by accident have reported very good results, he adds. “It’s certainly something to consider and could be used with other measures, such as seed-bed consolidation, to bring down the number of slug pellet applications.”