(CNN) -- Japan's green tea fields sway in the early summer winds, the picture of bucolic beauty. But beneath these peaceful rows of young green buds, ready for the second harvest of the year, a national crisis is brewing.
Earlier this month, Japan's government banned green tea from parts of three prefectures: Tochigi, Chiba and Kanagawa; and banned tea from all of a fourth prefecture, Ibaraki.
The authorities had detected levels of radioactive cesium in tea leaves above the legal limit of 500 becquerels per kilogram.
Now the discovery of radiation in fields further south in Shizuoka, Japan, some 400 kilometers away from the crippled Fukushima Daiichi Nuclear Plant, threatens the most robust tea-producing region in Japan.
The Shizuoka government says it asked five tea manufacturing plants in the Warashina district of Shizuoka to voluntarily stop shipping green tea leaves, after tests revealed dried tea contained 581 to 654 becquerels of cesium per kilogram.
It's the worst crisis in the country's centuries-long tea farming history, says Kotaro Tanimoto, of the Japan Tea Exporters Association. The association says foreign and domestic demand has dropped dramatically, even before these radiation discoveries. This latest news has now plunged the industry into a panic.
"We farmers can accept natural disasters like typhoons and droughts," says third generation tea farmer Hiroyuki Aoshima.
But he adds the nuclear meltdowns are man-made, hurting not just his harvests this year, but Japan's economy and global image. He doesn't understand how radiation could fall in his prefecture, so many kilometers away from the plant. "It's unfair," he says.
Since the nuclear crisis began on March 11, Japanese authorities have slapped bans on food products from milk to spinach, simultaneously assuring the public and export nations it is strictly regulating products.
The global consumer doesn't take the time to check which food item is deemed safe at any given time, says CNN contributor Jim Walsh, an expert in international security and a Research Associate at the Massachusetts Institute of Technology's Security Studies Program.
Walsh calls the drop off in global demand for Japan-made food products "the nature of the beast."
He points to the Ecoli crisis in Europe and the very strong consumer reaction there. "When people are fearful, they're not going to buy your products, no matter how many times you tell them they're safe," he says.
"I think this is going to be an ongoing struggle for some Japanese products, agricultural products in particular."
Green tea, which ships to high end tea buyers in the U.S. and Europe, is closely aligned with Japan's national character. While sugary sodas have infiltrated the daily diet here, green tea remains the country's national beverage.
But even Japanese consumers are more reluctant to consume green tea, given the latest news. Naoe Kukita, an avid green tea drinker, quizzed her tea merchant about the origin of the tea on the shelves, down to which harvest it came from. "We need to have access to all the truth and information," she says.
The Japan Tea Exporters Association says it is fighting its own truth campaign, brazenly protesting government regulations in a culture that is often reluctant to speak out against rules.
Tanimoto calls the current government radiation limits on tea "stupid regulations." He, and many farmers in Shizuoka, say the rules make no sense for tea's common usage. Tea, unlike spinach, they say, is used in small amounts and steeped in water. But current government regulations measure the dried leaves per kilogram, not the final tea product.
"That means if this tea is contaminated," says Tanimoto, holding up half a kilo of dried green tea leaves, "you'd have to eat all this tea, every single day, for an entire year before hurting your health. That's the same as drinking 200 bottles of green tea every single day for an entire year. No one does that. It's impossible."
Japan's health ministry, in response to a CNN inquiry, says it will review food safety standards this summer. That review will look at radiation safety standards for tea.
That's too late, argue the farmers, who fear this year's exports have already gone down the drain.