(UPDATED COVERAGE Nov. 25) The International Longshore and Warehouse Union is limiting its participation in West Coast port negotiations for 12 days through the Thanksgiving weekend, according to the Pacific Maritime Association.

The only bargaining through December 1 will involve subcommittees discussing limited issues. The employers group wanted full negotiations to continue.

“We have made it abundantly clear that we believe these negotiations are of the utmost importance and should continue at full strength until the Thanksgiving holiday,” Pacific Maritime Association spokesman Wade Gates said Nov. 20 in a news release.

The employers group also accused the union of refusing to agree to a temporary contract extension similar to one signed over the summer. Such an extension would give both sides access to grievance procedures.

The two sides have been without an agreement since July 1. In recent weeks both sides broke silence to trade accusations about delays and congestion at the ports of Los Angeles, Long Beach, Calif., Oakland, Seattle and Tacoma, Wash. Management complained of a labor slowdown. The union has repeatedly denied such claims, pointing instead to a shortage of chassis and rail cars among other causes.

Exports of apples and potatoes are among fresh produce cargo affected by the delays.

The Agriculture Transportation Coalition scheduled a Nov. 25 news conference in Seattle to discuss the effect on business.

“Harvests of apples, potatoes, hay, wheat, Christmas trees and other perishable Washington state produce are not being shipped out and may be completely ruined,” an ATC statement said. “If not shipped immediately, future contracts are in jeopardy as international customers seek more reliable supplies, putting local and family farms in peril.”

Industry groups asked President Barack Obama to intervene with federal mediation — but they may not get their wish.

“Just last year, there was a long negotiation at the East and Gulf Coast ports,” White House spokesman Frank Benenati said in a Bloomberg.com report. “And just as the two sides in that case were able to resolve their differences through the time-tested process of collective bargaining, we’re confident that management and labor at the West Coast ports can do the same.”

Management reports productivity is 30% or more below normal at the ports.