A farmer harvests corn in Burlington Iowa. Getty Images

There's growing concern in agriculture industry about fallout from anti-Mexico rhetoric in the Trump administration hurting American farmers. The prospect of a trade war with Mexico is particularly troubling for some in the nation's farm belt given low-commodity prices last year hurt U.S. farm incomes and this year also looks to be tough. Furthermore, many of the key farm states where President Donald Trump found the strongest support in the election could suffer the effects of a trade war with Mexico. "Mexico is a huge market for the agriculture economy of the United States," said Kurt Hora, who grows corn and soybeans on about 1,800 acres in southeast Iowa and raises thousands of hogs. "We want to make sure we continue to get market access down there."

Mexico is considered one of the most lucrative markets for U.S. agriculture products given its easy access and close proximity to the U.S, whether via rail, ship or truck. Overall, Mexico is the third-largest agricultural export market for the U.S. and ranks a top market for American corn, barley and poultry. But a so-called "Plan B" by Mexico leaders to wean themselves off U.S. imports could change that. The U.S. beef and hog producers also have benefited from duty-free access to Mexico's market under NAFTA, the North American Free Trade Agreement. U.S. pork hams are top sellers in Mexico but on Thursday one of Mexico's largest pork processors announced a $550 million multiyear expansion that could see it eventually export to Asian markets now dominated by the U.S. pork industry. Trump campaigned with a pledge to renegotiate NAFTA and also has talked about getting Mexico to pay for a new border wall through a tax. On Thursday, Commerce Secretary Wilbur Ross said the administration wants to start the NAFTA renegotiation process before Congress leaves on its Easter recess. Meantime, Mexico has promised to retaliate with tariffs on goods imported from the U.S. "The rhetoric is getting into the way," said Thomas Sleight, the president and CEO of the U.S. Grains Council, a trade group which develops export markets for corn, barley and related products. "We have buyers and customers that are unhappy with some of the things that have been said." Indeed, a delegation from Mexico's agriculture ministry is scheduled to travel to Argentina and Brazil next week to discuss the expansion of ag trade ties. CNBC reached out to the ministry for comment. Mexico is said to be looking at a duty-free trade pact on corn with Argentina and Brazil. "They're actively looking for alternative suppliers," said Sleight, who just returned from a trip to Mexico last week. He said there's talk south of the border about a "Plan B," or strategy by the Mexican leaders to reduce the country's reliance on the U.S. A decline in agricultural trade with Mexico would be an economic blow to American farmers but could have ripple effects for consumers too. Earlier this year, the Trump administration discussed a possible border tax on imports from Mexico that would result in higher prices on all products, including Mexico's popular avocados.