Being ‘water aware’ could save key pesticides

At-risk pesticides could be lost or subject to regulatory restrictions as early as 2016 if voluntary initiatives to prevent them reaching drinking water supplies are not successful.

Slug-killer metaldehyde has long been in the spotlight as it is regularly found in surface water above the limit outlined in the Water Framework Directive (WFD) and is extremely costly for water companies to remove before reaching customers’ taps.

But now there is a worrying trend of exceedances involving key herbicides used in oilseed rape, and these chemicals have joined metaldehyde as “under threat” from increased regulation or even bans.

See also: Multi-agency scheme to save metaldehyde slug pellets

Chief pesticide adviser at the Environment Agency, Jo Kennedy, said that about 40% of the 485 drinking water catchments in England and Wales are at risk from pollution.

WIYBY tool

The What’s in Your Back Yard, or Wiyby, tool on the Environment Agency’s website enables farmers to check whether their land included in “safeguard zones” that are classified as high-risk for pollution of drinking water.

Jo Kennedy explained that many growers may not be aware that they are in a drinking water catchment and urged them to use the tool to find out and see what measures are in place, if any, to mitigate the risk.

“The biggest problem is pesticides, which cause the pollution risk in 23% of catchments, with metaldehyde, and oilseed rape herbicides, the usual suspects,” she told a briefing to launch Makhteshim-Agan UK (Mauk) initiative Water Aware.

Defra’s public consultation on pesticides in drinking water will end in 2015. Based on its findings, the government will draw up and start implementing measures to ensure the UK meets Water Framework Directive (WFD) targets.

These will be in addition to those being considered for inclusion in the second round of the River Basin Management Plan which will run from 2015 to 2021 – the vehicle used to achieve WFD targets.

There is a very real risk measures taken forward following the consultion will include legal restrictions on problem pesticides if their levels in water do not start to drop, said Ms Kennedy. But she added that there is still time for the industry to try and prevent this.

Current measures, which are all voluntary, haven’t managed to reduce pesticide pollution in all catchments since WFD rules were introduced in 2008.

“However, Defra is still committed to trying to find voluntary solutions to balance reducing environmental impact of pesticides and securing adequate food production,” says Ms Kennedy.

Jacky Atkinson of the drinking water inspectorate agreed, explaining that catchment management measures in high-risk areas need to work in the coming years.

“If the voluntary measures are proved to be working, we won’t need regulation and it will be business as usual for farmers and the water companies. But it has to be affordable to the [water] customer,” she said.

Responsible use

Water Aware is aimed at promoting responsible use of the current chemistry coming under increasing pressure from issues surrounding water, as well as taking a proactive position on emerging and any potential future issues.

It aims to bring together industry stakeholders including manufacturers, distributors, agronomists, farmers, water companies, the Environment Agency, government and regulators.

The initiative will pay particular attention to oilseed rape herbicides metazachlor and carbetamide – actives that along with propyzamide and quinmerac threaten a significant number of drinking water catchments.

Mauk senior crop team lead Paul Fogg said that the increasing trend of water exceedances for oilseed rape herbicides is something that needs to be reversed.

“The oilseed rape area has doubled in the past decade and 40% of that area is estimated to have blackgrass, so it isn’t going to be easy.”

Jodie Whitehead of Severn Trent Water added, “We have proved that targeted measures can work with metaldehyde, where a pilot scheme encouraging farmers in high-risk catchments to use alternative products to control slugs has been implemented.”

In 2012, which was a high slug pressure year and extremely wet in the autumn, a 50% reduction in metaldehyde exceedances was achieved in the Avon and Leam catchment area in Warwickshire, compared with 2008 – the last season with similar conditions.

What is Water Aware?

  • An industry-wide initiative to safeguard the future of plant protection products that pose a risk to water quality without regulation
  • A platform for growers, agronomists, agrichemical manufacturers, water companies, government and legislators to address issues together
  • Compliments the Voluntary Initiative and other industry-led stewardship campaigns
  • Focuses on oilseed rape herbicides such as carbetamide

About 300 farmers adopted the measures in the catchment, but Dr Whitehead concedes that the issue of oilseed rape herbicides is much more difficult to address.

“I’m not sure where the industry can go with these products because unlike metaldehyde, where you can switch to ferric phosphate, there are currently no alternatives,” she added.

Metazachlor and quinmerac are used slightly earlier in pre- or early post-emergence herbicide applications, but carbetamide and propyzamide are used later, from November onwards, to target blackgrass. That winter timing, combined with heavy soils and the presence of artifical drainage, provides the ideal conditions for pesticide compounds to get into surface water.

Carbetamide timing moved

As part of Mauk’s commitment to maintaining plant protection solutions for growers under the Water Aware umbrella, it has acknowledged the problem with carbetamide and is seeking to reposition its use.

Many of the ACCase-inhibiting graminicides that are used in oilseed rape ahead of a carbetamide or propyzamide application in the winter, such as Laser (cycloxydim) or Aramo (tepraloxydim) are failing due to target site resistance in blackgrass.

Dr Fogg explained that new work conducted by the company shows carbetamide, contained in its product Crawler and with no known resistance problems, can work effectively at an early timing to replace the ACCase inhibitor in the sequence.

“We know carbetamide is highly water soluble and using it in the current November-onwards timing isn’t sustainable. So we are advising using the product in mid- to late-September,” said Dr Fogg.

He added that its water solubility is an advantage when moisture is at a premium and tests have shown that the product remains effective even when the soils are at the drier end of the soil moisture release curve.

“Blackgrass will be under pressure in drier conditions and scavenging for water, so the plants should take up the product readily,” Dr Fogg said.