According to reporting in Reuters, Western Growers, a trade group representing companies that produce nearly half of US fresh vegetables, fruits and tree nuts, confirmed that many of its members had received import declaration requests from Chinese authorities.

"It's changing how some of our growers are reacting to the marketplace," said Dennis Nuxoll, the trade group's vice president of federal government affairs. "Some of them are not going to export."

Nuxoll declined to say which companies were backing away from shipments to China

Western Growers complained this week to the US Department of Agriculture and US Trade Representative over the issue, and the government said it would take it up, Nuxoll said.

The USDA and USTR did not immediately respond to requests for comment.

In a statement on 24 June, the USDA and US Food and Drug Administration said: "Efforts by some countries to restrict global food exports related to COVID-19 transmission are not consistent with the known science of transmission."

China, where the coronavirus pandemic originated, is trying to prevent any possibility of new infections coming from imported goods as it takes aggressive measures to contain a recent spike linked to a wholesale food market in Beijing.

Global meat exporters like JBS SA, along with some US produce suppliers, have agreed to sign declarations ensuring the safety of their shipments. Others that export produce and soybeans have scoffed.

Produce exporters are nervous that Chinese authorities could reject perishable goods, making the shipments a total loss, Nuxoll said.

"We are aware that the Trump Administration has objected to China's actions and request that the administration continue to pressure the Chinese government until it reverses this ill-timed and scientifically indefensible trade barrier," said Dave Puglia, Western Growers' president and chief executive.

Read more about this story here.