Some of the biggest US agriculture trade groups are urging Canada’s prime minister to step in to avert a rail strike in the country that could disrupt the flow of North American commodities.

“We request that you take action to ensure railroad operations continue before a lockout or strike occurs to prevent serious damage to the Canadian and US economies,” 35 US industry groups wrote in a letter to Prime Minister Justin Trudeau.

Two of Canada’s largest railroad companies said they’ll shut down operations Thursday if they fail to reach an agreement with more than 9,000 of their unionized workers. The two companies account for 80% of Canada’s rail network.

The agriculture industry ships more than 25,000 rail cars a week of goods on Canadian National Railway Co. and Canadian Pacific Kansas City Ltd. and that figure would “go to zero” during a strike or lockout, according to Monday’s letter signed by groups including the U.S. Grains Council, American Farm Bureau Association and the National Grain and Feed Association. 

Agriculture is particularly exposed to rail stoppages given that farmers rely on railways for the timely delivery of fertilizer, crop inputs and feed grains for the livestock industry, according to the letter. Biofuels operations, flour mills and other agriculture operations also require uninterrupted rail service.

Canadian Labor Minister Steven MacKinnon and federal mediators are set to meet with the parties on Tuesday and Wednesday, after the government declined to impose binding arbitration last week.

“Operational railroads are essential on both sides of the border for the integrated North American supply chain,” the groups wrote in their letter. “While we believe a negotiated solution is always the preferred outcome, your government should be prepared to move quickly if negotiations fail.”