20 May 2022

Longford Leader Farming: Herbicides (MCPA) and Water Quality

Teagasc provides educational information to local farmers

Teagasc New Office Opened

In recent years, there have been frequent detections of herbicides in streams, rivers and lakes throughout the country, including some water bodies used for the supply of drinking water (examples Lough O’Gara in Roscommon and Lough Forbes in Longford).

These persistent cases are a continuous concern and clearly indicate that a small number of farmers are not handling products with sufficient care. The herbicide causing the greatest problem is MCPA (sold as Agritox, Agroxone 50, Mortone, M50 etc) and is commonly used on grassland farms to control rushes and other weeds.

The Lough Forbes Catchment borders three counties Longford, Leitrim and Roscommon and includes the towns/villages of Rooskey, Dromod, Mohill, Termonbarry, Newtownforbes, Drumlish, Ballinamuck and Bornacoola.

This year the catchment is part of a national monitoring programme for MCPA, involving intensive water sampling on a weekly and fortnightly basis from March to October.

There are 12 sampling locations throughout the catchment on the Black River, Eslin River, Rinn River, parts of the Shannon and a few smaller streams.

The results to date are very concerning. On each of the sampling dates there have been a number of exceedances detected. The highest number occurred at the end of May when 8 of the 12 sites exceeded the limit.

There have been 4 or 5 breaches on most of the sampling dates. Only one site has returned no exceedance during the period. The most recent result highlighted 3 exceedances which is a slight improvement. However, the situation must improve further or else MCPA could be prohibited for use and a cost control measure for rushes will be lost.

What should farmers do?

Frequent topping and good drainage will help limit rushes spreading. However, if the rush infestation is heavy then topping or mulching followed by weed licking with Glyphosate after 5/6 weeks is the most suitable option when water quality is a major concern.

If you choose to use MCPA then you must take precautions by following best practice: The chemical MCPA cannot be used in a weedlicker or knapsack sprayer, it cannot be sprayed within 5m of watercourses and dry drains.

Do not fill the sprayer from a watercourse. Spray at the right time- a young healthy growing crop, suitable weather conditions and when there is no surface water present. Empty containers should be triple rinsed and the rinse put into the sprayer. The tank washings must be sprayed in the field and not emptied in the farmyard.

Teagasc provides a Local Advisory and Education service to farmers. They have offices based in Longford Town (Tel: 043 3341021), Roscommon Town (Tel: 090 6626166) and Castlerea (Tel: 094 9620160). You can find us on Facebook @Teagascroscommonlongford.

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