Mexico needs to prove itself a responsible trade partner if the country wants to be a trusted member of the Trans-Pacific Partnership trade agreement, a U.S. potato grower told Congress.

Speaking about Mexico’s trade restrictions on U.S. potatoes, Roger Mix, past president of the National Potato Council, Washington, D.C., and potato grower with Mix Farms, Center, Colo., testified at a late July hearing of the House Small Business Subcommittee on Agriculture, Energy and Trade. In July, the U.S. Trade Representative said the U.S. was beginning negotiations with Mexico to join partners Australia, Brunei Darussalam, Chile, Malaysia, New Zealand, Peru, Singapore and Vietnam in the ongoing talks toward a new trade agreement.

Speaking at a hearing titled ”Market Closed: Foreign Trade Barriers Facing Small Agriculture Exporters,” Mix said a March 2003 U.S.-Mexico market access agreement that allowed for the shipment of U.S. fresh potatoes from all 50 states into a 26-kilometer deep area along the border of Mexico has failed to live up to expectations.

Mix said the 2003 agreement called for increased access to the five northern Mexican states in 2004 and for consideration of full access by 2005.

Even so, Mexico continues to restrict the shipping of U.S. fresh potatoes to Mexico to 26 kilometers, Mix said. Although fresh potato exports to Mexico registered $39 million in sales in 2011 — the second largest export market behind Canada — Mix said full access to the Mexican market would translate to export sales of $150 million.

Many of the obstacles raised by Mexico since 2003 to prevent U.S. potato market access have not been based on sound science, Mix said. Without visible progress and a final work plan that will give U.S. potato exporters full access to Mexico, Mix said Mexico’s credibility as a responsible trade partner in the Trans-Pacific Partnership Trade Agreement should be called into question.

The Office of the U.S. Trade Representative is taking comments on Mexico’s participation in the Trans-Pacific Partnership Trade Agreement until Sept. 4. The trade office is also taking comments until Sept. 4, at  on Canada’s participation in the trade pact.