Tillage farmers continue to find fields infested with the scourge of blackgrass nationwide.

Farmers on land which had no history of blackgrass are having to destroy sections of their crop and take fields out of cropping to halt its spread.

It remains a mystery as to how the problem is arriving on these farms and assessments have shown that these plants show resistance to all current herbicide chemistry.

One grower in Co Kildare is about to remove a section from his winter wheat crop for the second year in a row in order to destroy a swath of dense blackgrass. Blackgrass is flowering at the moment so this action prevents it producing seeds.

Virtually nothing is being brought on to this farm so it is a mystery as to where these infestations are coming from. But in both fields, oilseed rape was the preceding crop and this may be camouflaging the expansion of the problem.

However the question remains as to where the initial seeds are coming from.