In a sudden, unprecedented move, China has banned imports of California citrus over disease concerns.

The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service received a letter from Chinese officials early the week of April 15 stating that as of April 18, California citrus would not be allowed into China, said Tanya Espinosa, an APHIS spokeswoman.

The ban does not effect citrus imported from Florida, Arizona and Texas, she said.

Chinese officials said they found fruit with the disease Phytophthora syringae, or brown rot, in a few loads of fruit shipped in February, said Joel Nelsen, president of Exeter-based California Citrus Mutual.

Officials from APHIS, the Chinese government, California Citrus Mutual and the California Citrus Quality Council, researchers at the University of California-Riverside and others were discussing the issue the week of April 15 in hopes of finding a less drastic solution, Nelsen said.

The fate of fruit on the water the week of April 15 was unclear, Nelsen said.

What Espinosa characterized as a “fairly quick turnaround” between when Chinese officials notified USDA and the ban went into effect wasn’t the only thing that surprised the industry, Nelsen said.

“The fruit arrived in China in February, they confirmed (the brown rot findings) in March, and they didn’t notify us until last week. It caught us off guard.”

Nelsen also questions why China is instituting a blanket ban on all shipments, considering that fewer than 600 cartons — out of about 5 million shipped thus far — were found to contain brown rot, a quarantine disease that is not present in China.

Brown rot can occur when spores splash up from the ground into citrus plants during rainstorms, Nelsen said. Shippers and officials are confident that the risk of other loads being infected is very low since California’s citrus-growing regions have had such little rain, Nelsen said.

“These are isolated incidents,” he said.

What China could have done, Nelsen said, is required California shippers to beef up their postharvest treatments of fruit before shipping it to China. China’s blanket ban on all shipments, he said, is unprecedented.

California shipments to China were set to wind down in about mid-May, Nelsen said. California typically ships up to 11 million cartons of citrus to China annually.

“This is very important,” Nelsen said. “China is our second-largest export market.”