Farmers and other users of pesticides have been urged to exercise caution if applying weed control sprays as the end of the grazing season nears.

The national pesticides and drinking water action group (NPDWAG) and Uisce Éireann have said that sticking to best practice will help shore up the progress that has been made on boosting water quality of recent years.

The number of pesticide exceedances showing up in public drinking water supplies more than halved since 2017, with the improvement reflecting the efforts of farmers and the managers of amenity areas, the action group stated.

The NPDWAG’s call for responsible pesticide usage comes as it said that farmers may be considering availing of the opportunity to control grassland weeds such as docks, thistles and nettles towards the end of the grazing season.

Adhering to the closed periods for application is important due to wet weather conditions increasing the risk associated with pesticides reaching drinking water supplies, it said.

2025 risk 'high'

“Last year, we saw a worrying number of pesticide detections occurring outside the main spraying season for MCPA,” Uisce Éireann’s manager of drinking water compliance Dr Pat O’Sullivan warned.

“While this has not yet happened in 2025, the risk of it repeating itself remains high.

“We are urging all pesticide users to be mindful of their use as the spraying season comes to a close, so that we can avoid late-season exceedances again this year.

“Even one drop of pesticide can travel up to 30km in a watercourse, so every action counts.”

Dr Aidan Moody of the Department of Agriculture, who chairs the NPDWAG, said that “excellent work” has been seen from farmers in adhering to pesticides’ correct application methods.

“We urge everyone to continue the great work and always consider whether a pesticide is needed at all, and where it is, to make sure that best practices are followed,” Moody stated.

“This approach not only protects our drinking water but also supports biodiversity and healthy ecosystems.”

Advice

The two groups’ statement listed key messages all pesticide users:

  • Only use pesticides when necessary and after considering all alternative control methods.
  • Always read and follow the product label.
  • MCPA is not permitted for use from the end of September (or the end of October, depending on the particular product) until the beginning of March.
  • Never use pesticides if rain is forecast in the next 48 hours.
  • Keep well clear of watercourses, drains and wells, while observing buffer zones.
  • Avoid spills. Never fill or wash sprayers beside drains or on concrete where runoff can occur. Triple-rinse containers into the sprayer.
  • Dispose of unused product and containers safely.

    • More information can be obtained from your local farm adviser or by clicking here.