U.S. potato exports to Mexico have stopped in response to a lawsuit by Mexican growers.

While the Mexican government prepares its response to the suit filed by the Mexican Potato Producers Association (CONPAPA), U.S. spuds cannot be exported, said Workabeba Yigzaw, a spokeswoman for the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service.

Shipments that had been certified before June 9, when CONPAPA issued its injunction, were eligible for a phytosanitary certificate that allowed them to be shipped up to 16 miles inside the U.S./Mexico border, said Suzanne Bond, an APHIS spokeswoman.

The growers’ lawsuit seeks to block a new rule, which went into effect May 19, that allows U.S. potato exports to all parts of Mexico. Before that, exports were limited to the 16-mile zone.

Mark Szymanski, director of public relations for the National Potato Council, Washington, D.C., said it’s not a big surprise that the implementation of the rule is facing challenges.

“We always knew there would be some hiccups,” he said. “I don’t think anyone’s absolutely shocked.”

Jim Ehrlich, executive director of the Colorado Potato Administration Committee, Monte Vista, Colo., agreed.

“We’ve heard rumors for awhile that they could potentially file suit,” Ehrlich said. “The position of the Mexican growers all along has been that they want to protect their industry, and they have every right to do so.”

That didn’t make it any easier to accept for Colorado shippers, however. In the week of May 26, the first full week after the Mexican rule went into effect, Colorado growers shipped about 3.1 million pounds of potatoes to Mexico, Ehrlich said.

“Demand has been huge,” he said. “We’ve been trying to show as much restraint as possible and still meet demand. We’ve worked hard for ten years to make this happen.”

At the time the rule was announced, Szymanski said the value of annual fresh potato exports from the U.S. to Mexico could jump from $30 million to $100 million.