Using low 1.5% active substance metaldehyde pellets this autumn allows growers to use more than one application whilst keeping well within the Stewardship Guidelines, says Dr. David Ellerton, Technical Development Director for Hutchinsons.  "It makes sense to use less metaldehyde to reduce the risk of leaching, but it still has to do the job and kill slugs!"

David Ellerton reports that in autumn 2012 metaldehyde was widely detected in water with some peaks following rainfall.  "It was an exceptional but disappointing year for metaldehyde detections, but we still need to do something to prevent this happening again such as by using the minimum amount of active substance/hectare. It has been proven that the lower amount of active substance you put on, the lower the risk of leaching leading to metaldehyde peaks, hence the upper limits being set as part of the Guidelines."

He says that this means using the lowest active substance pellet, providing it works.  "Mathematically a 1.5% pellet applied at 4 kg/ha delivers 60 grams/ha of metaldehyde. This means that, whilst keeping well within the maximum application rate of 210 metaldehyde as/ha from the 1st August up to the 31st December, you can apply these pellets three times in the autumn. A 3% pellet applied at the same rate delivers 120 gms of metaldehyde and so can only be applied once at this rate."

Using a pellet little and often whilst keeping within the maximum limits must be the logical and the safest way forward, he says.

"Using the wet type 1.5% metaldehyde pellet, Attract, you have more leeway, more flexibility and more time to decide how to plan. But the low dose pellet has to work and there is much evidence that it does work," says David.

Dr. Dominic Lamb representing Chiltern Farm Chemicals explains that the 1.5% TR3799 pellet from Chiltern is specially formulated to work at much lower rates.  "It is finely milled and coated so that you need just 37µgms to kill a slug, compared with 205µgms of the standard metaldehyde. They are 5 times as effective at killing slugs as the standard product. The special formulation works at lower rates and has the benefit of being less risk to water."

"Advisors and growers have to go for the most active pellet that delivers the most baiting points at the lowest active ingredient levels. It is a very straight forward decision. The Chiltern TR 1.5% wet process range at 4kg/ha delivers 60 grams metaldehyde per hectare, 80 baiting points/square metre and the opportunity to apply up to 3 times in the autumn without contravening the 210 grams limit," says Dominic.

The recommendation for autumn 2013 is 4 kg/ha of Attract, a 1.5% wet metaldehyde pellet, with a maximum of three applications post-drilling of cereals or oilseed rape.