Tanking care with MCPA and such products

With the spraying season for rushes now very much upon us, this information note highlights important changes to labels as they affect ‘‘straight’’ MCPA products.

MCPA

In recent years, there have been frequent low-level detections of a number of herbicides in surface water bodies (streams/rivers/lakes) throughout Ireland including, in some cases, water bodies used for the supply of drinking water. While the levels being detected do not pose any health risks, the presence of pesticide residues in water bodies ultimately ending up in drinking water supplies is a cause for concern.

MCPA residues account for the greatest number of detections in drinking water supplies nationwide, with levels in many cases above the legally permissible limit of 0.1 part per billion (ppb). A single drop, or foil seal from a pesticide container, could potentially cause an exceedance along a small stream for a distance of 30km. Careless storage, handling, filling or use of pesticides, or improper disposal of foil seals or empty pesticide containers, can easily cause breaches of the limit.

MCPA is the active substance (AS) in a number of herbicides predominantly used by grassland farmers to control rushes, as heavy infestations of this weed may have implications for land eligibility. In many regions, the problem with rushes will have been exacerbated by the recent sequence of wet summers, which has further restricted control opportunities in recent years.

Given the myriad of uses of pesticides (plant protection products and biocides) in the world today, some detections are inevitable, but repeated breaches of the 0.1ppb limit indicate that the products are not being used with sufficient care. If the situation in general, and more specifically in relation to MCPA, does not improve, the future for these products in certain areas remains in doubt.

Use guidelines

The following guidelines should be noted and acted upon by all users of plant protection products to ensure the quality of Irish water courses and to reduce, in particular, the levels of MCPA detected.

Label changes

To further ameliorate the problem, the pesticide controls division (PCD) of the DAFM has revised all existing labels for straight

MCPA-based products. Label changes came into effect from December 2015 and these now stipulate a revised maximum individual dose (MID) of 1,350g as/ha for straight MCPA products – see Tables 1 and 2.

Effectively, the maximum application rates for these products have been reduced. The following is also applicable to existing and re-registered straight MCPA products:

Some of the products being removed from the market in Table 2 have been re-registered for use with different PCS numbers and lower application rates. These products cannot be applied using a knapsack sprayer.

When using any plant protection product, read the label carefully and follow all guidelines. Take special care to avoid contamination of water courses. Remember, if you do not use these products appropriately, the ultimate sanction is that they will be prohibited, and an important, cost-effective control measure will be lost.