Up to a quarter of the oats crop grown on contract by Flahavans was destroyed in the recent cold snap, the company has confirmed.
Flahavans operations manager John Coffey confirmed that the company, which is Ireland's biggest buyer of oats, was concerned about the potential for significant crop losses.
Crops in Tipperary, where the company sources half of its 14,000t annual requirement for conventional oats, have been particularly badly hit.
Some individual growers there have already ploughed the crop back into the ground in preparation for re-planting a spring crop, while at least one grower in Kilkenny has lost 100ac of oats.
"While the crops looked poor last week, there was some indication of life and signs that the plants could recover, but in the past few days they have gone downhill," said Mr Coffey.
"I am reluctant to give a figure for how much has been damaged in Tipperary, but it would be a high percentage, over 50pc of the crop."
If these early estimates come to fruition, that would equate to the loss of 3,000-4,000t of oats.
Crops of Barra, Husky and Circle were worst affected, as they are actually spring varieties, although they are often sown as winter crops. The only true winter variety, Mascani, appears to have withstood the freezing conditions.
Most farmers would probably decide to cut their losses by ploughing the crop and replacing it with a spring crop, claimed Mr Coffey.