NI Water remains keen to promote weed-wiping with glyphosate as a substitute to spraying with MCPA for the control of rushes on agricultural land.

A free weed-wiping service for farmers in the Eden Burn sub-catchment of the River Bann has been launched and will run from April to October in 2019 and 2020.

Speaking to farmers in Ballymoney last week, Roy Taylor from NI Water said that the new service follows on from similar initiatives, which started in the Seagahan catchment in Armagh in 2017 and in the Glenhordial catchment outside Omagh last year.

The aim is to reduce the amount of MCPA that enters waterways and subsequently needs to be removed at water treatment works by NI Water.

Weed-wiping with glyphosate is the preferred option for rush control from a water quality point of view.

Taylor said that a set of carbon filters for removing pesticides can cost £5m and annual running costs can reach up to £50,000. He said that MCPA lingers in water for 30-40 days, whereas glyphosate-based pesticides, such as Roundup, break down naturally within three to four days.

The free weed-wiping service in the Seagahan catchment saw MCPA levels reduce by 50% in the first year and by 75% in year two.

According to Taylor, NI Water spent around £20,000 on the weed-wiping service, but saved £50,000 in water treatment costs.

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The results from the first year of the Glenhordial catchment are less clear, as water from a neighbouring catchment with relatively high MCPA levels also enters the local treatment works.

Taylor said that NI Water would assess the results from the Eden Burn catchment over the next two years and will consider extending the service to other areas in NI that have an MCPA problem.

“It certainly won’t be rolled out everywhere, but wherever it’s feasible to do and wherever there is a problem then we will be looking at it,” he said.

Farmers were told that the aim of the project is to demonstrate that weed-wiping with glyphosate can provide an effective rush kill.

A four-year study by CAFRE has also found that glyphosate was more effective at reducing rush covers than MCPA.

However, some farmers in Ballymoney made the point that MCPA was still needed for controlling other weeds, for example thistles and buttercups.

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