The Greencore group of unions and the Irish Farmers Association (IFA) decided on a joint approach to the issue at a meeting.
Irish Sugar, part of Greencore, plan to close the factory in March and consolidate all sugar processing in Mallow.
This will result in the loss of 189 full time and 137 seasonal jobs.
SIPTU’s Carlow branch secretary Mick Browne said factory workers and beet growers stated that they were not prepared to accept the threat to their livelihoods, simply to satisfy the greed displayed by Greencore management.
Mr Browne said it was irresponsible of Greencore to propose closing a plant, which is generating in excess of E10 million profits, in order to capitalise on the potential development value of the site, regardless of the consequences for the workers or the community.
The Labour Parliamentary Party, noting the importance of the sugar factory to farming and the local economy generally, called on the Government to immediately seek a meeting with the Greencore board with a view to seeking a reversal of the decision.