“People just don’t understand what hemp is,” said Jeffrey Cox, the head of Illinois’s bureau of medicinal plants, who oversaw a small hemp field at this summer’s state fair to introduce the new crop. “I had to explain that it’s not marijuana to hundreds and hundreds of people.”

Hemp was grown in American fields until the 1930s, when it was included in federal legislation restricting marijuana. Even then, it was not eradicated: Wild hemp is often called “ditch weed.”

This year, about 1,000 farmers in Illinois applied to grow fewer than 23,000 acres of hemp , according to John Sullivan, the director of the Illinois Department of Agriculture. That is minuscule compared with the acres of corn (11 million) and soybeans (10.8 million) planted last year. But some see it as a necessary alternative.

“Our corn and soybean farmers have lost customers,” Governor J.B. Pritzker of Illinois said. “And when you have a large customer and you lose them in a given year, it’s very hard to get them back.”

Mr. Huston, who voted for President Trump and intends to do so again, said he believed that the president had good intentions in his trade standoff, although like other farmers, Mr. Huston said he was frustrated and had suffered from its effects.

“ It’s a bad way to do business,” he said. “If we end up with better markets at the end of this, it will have been worth it. But I don’t know if that’s likely.”