The AFL-CIO Tuesday announced a nationwide consumer boycott of American Crystal Sugar as a lockout of the company's 1,300 union workers drags into its 15th month.

Moorhead-based Crystal Sugar on Aug. 1, 2011, locked out workers at its five Red River Valley plants -- including three in Minnesota -- after they rejected a contract. Workers have since turned down roughly the same contract two more times, including in late June.

The AFL-CIO, an umbrella group for U.S. organized labor, called for a boycott until Crystal Sugar bargains in "good faith" and a new contract is reached.

Crystal Sugar, a farmers' cooperative, is the nation's largest beet sugar producer. Almost 90 percent of its production by weight is sold to industrial users such as confectioners, bakeries and breakfast cereal makers, according to a federal securities filing.

The remainder is sold in retail channels under the "Crystal Sugar" moniker, as well as private label brands.

The AFL-CIO said in a news release it "endorses boycotts cautiously and only in instances of grave injustice."

Brian Ingulsrud, a Crystal Sugar spokesman, said the company is concentrating on the beet harvest, which kicks into high gear this month. "Our focus is the large crop coming at us, and the employees who are in place to get that done are doing a great job."

Crystal Sugar's plants have been running with temporary replacement workers since the lockout began.

While Crystal Sugar offered union workers a raise of 13 percent over five years, it has also proposed health care cuts and contract language that would erode some union rights, notably seniority.

Mike Hughlett • 612-673-7003