Protect our water quality when using pesticides

Poor practices can result in spillages into watercourses. For this reason, NI Water is providing advice on how to apply pesticides using best practice to protect the quality of our water.

There are two main chemical methods for controlling rushes, these are glyphosate and MCPA. Glyphosate is a broad-spectrum systemic herbicide and MCPA is a selective herbicide specifically designed to kill weeds without harming crops and is a common active ingredient in both agricultural and domestic herbicide products.

Routine passive sampler monitoring of water in the rivers and lakes has shown high levels of grassland pesticides such as MCPA, which could be from agricultural activity such as controlling rush infestation using a boom sprayer applicator.

Farmers should apply pesticides using the instructions on the container and following best practice guidelines from DAERA. Following this advice will benefit NI Water as taking MCPA out of water is costly and requires the use of Granulated Activated Carbon (GAC) filters, with regeneration of one of these filters often costing in excess

of £20,000.

NI Water recommends using glyphosate weed-wiping and then to top the rushes off a month later. Tips for using this method include:

- Ensure you choose the correct time to treat the rushes. It is best to treat young rushes before they turn brown. This usually occurs about 6 weeks after

a mature plant has been cut. This is effective because the outer skin is less waxy and allows the chemical to enter the plant.

- The trampling of cattle especially but also sheep can cause seeds to germinate. Grazing of your field must be carefully managed. It is recommended that fields are grazed well before using weed-wiping equipment.

- Topping the rushes alone is not a sustainable method of managing rush. For this to potentially work, topping would need to be done 6 times a year, but this would be expensive and time consuming. Topping rushes usually only keeps them at bay for 2/3 weeks.

- Lastly, it is important to remember that pesticide application is not effective at controlling rush. It is just as important to ensure your field has good drainage and correct pH levels. In optimal conditions grass will naturally outcompete rushes.

NI Water is also using the day to launch its draft ‘Water Resource & Supply Resilience Plan’. The draft Plan is an important document for NI Water, as it shows how the company will manage and develop water resources to make sure there is enough water to meet future supply needs. It is being made available for

public consultation for nine weeks, closing on 24 May 2024. Further information is available on: https://www.niwater.com/managing-northern-irelands-water-resources/