Metaldehyde levels in water continue to be a problem, but this autumn is particularly crucial as its metaldehyde levels will be used to recommend revisions to the drinking water standards. Extra care with the active ingredient is essential, if farmers are to continue to benefit from the effective molluscicide, the Metaldehyde Stewardship Group (MSG) warned at a meeting of interested parties last week. With methiocarb already withdrawn, there are less slug control products available.

The MSG was formed by the major slug pellet manufacturers and distributors in 2008 to raise awareness of the active ingredient’s water pollution problem, says MSG chairman David Cameron of De Sangosse. It has worked hard to get its message across to the supply trade and users, through investing in training – especially on careful storage, handling and applications. While the MSG Guidelines are unchanged, the campaign has evolved over the years with more focus on high risk areas in the intervening years.

The Environment Agency notes that water quality has significantly improved over recent decades, but that metaldehyde levels in some catchments pose a risk of failing to comply with the objectives set to protect drinking water sources. Mr Cameron estimates that 80% of slug pellets now contain metaldehyde, with the potential cost of slug damage to farmers and growers without effective control products exceeding £100m annually. While ferric phosphate products are available, they only account for around 5% of the market.

The problem is that metaldehyde is expensive to remove from water supplies, so water companies would rather it was not present in their raw supplies in the first place.

Milo Purcell, deputy chief inspector of drinking water at the Drinking Water Inspectorate (DWi), warned that this season is critical. The water companies have to provide a report to the DWi by March 2017 on their progress to date and outcomes of their catchment measures, together with proposals to ensure future compliance with the standards until the end of 2019. This date for this report has been brought forward by a year.

 In turn, the reports on water metaldehyde levels up to March 2017 will inform the government’s decision whether to change the current standards. The Environment Agency is working closely with Defra and the DWi on policy proposals to reduce metaldehyde levels in the future, although the timetable may be delayed by the Brexit work. The Agency supports industry self-regulation initiatives and water company programmes to reduce water pollution, but they must be seen to work.

Therefore, Mr Purcell warned that the industry must “up its game” still further in reducing metaldehyde pollution – while there has been success at local levels, there had been little progress in reducing metaldehyde in drinking water at a national level.

Independent agronomist Colin Myram noted that the above average rainfall from November to June had encouraged slug numbers, possibly to 2012 levels, although the relatively dry July and April may have helped reduce populations. Cultural techniques to help combat slugs include early drilling, deeper sowing for wheat, cultivations to destroy or bury slug eggs and rolling to consolidate ground to make slug movement harder. While these don’t always suit minimum tillage and blackgrass control strategies, seed treatments and more spring cropping can also help reduce slug numbers. Farmers should also encourage carabid beetles which feed on slugs and eggs – although one side effect of the neonicotinoid restrictions is a rise in the use of pyrethroid products which harm carabids.

This is a critical season for slug control, a message the distribution trade needs to get across to farm clients, whether through company agronomists or via the AICC to the independent sector, the meeting concluded. Operator training programmes will also highlight the message.