The Environmental Risk Management Authority has issued a reminder that all stocks of the endosulfan must be safely disposed of by mid-January. The insecticide is now prohibited.
Endosulfan is highly toxic to humans and in the aquatic environment.
It was used on a variety of crops including vegetables, berry fruit, citrus, and ornamentals, as well as for earthworm control in turf.
It was banned from use last year, when ERMA concluded that the risks of using the insecticide outweighed the benefits.
However, a year's grace was given for disposal of any unused stocks.
ERMA has been working with regional councils, waste disposal contractors and industry associations to ensure its safe disposal. A rural recycling programme, Agrecovery, is also collecting it.