Banana lovers take note: The world's supply of the fruit is under attack from a fungus strain that could wipe out the popular variety that Americans eat. "It's a very serious situation," said Randy Ploetz, a professor of plant pathology at the University of Florida who in 1989 originally discovered a strain of Panama disease, called TR4, that may be growing into a serious threat to U.S. supplies of the fruit and Latin American producers.

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"There's nothing at this point that really keeps the fungus from spreading," he said in an interview with CNBC.

While there are nearly 1,000 varieties of bananas, the most popular is the Cavendish, which accounts for 45 percent of the fruit's global crop—and the one Americans mostly find in their supermarkets. Read MoreWanted: More young people for an old US industry

The Cavendish became a favorite in the 1950's because it was found to be resistant to strains of Panama disease that hit the then-preferred Gros Michel variety of banana. But now the Cavendish, which makes up about 95 percent of global banana exports, is dying from the fungus strain Ploetz found. The strain has hit the banana crop in Asia, the Middle East and Africa. The worry is that it will spread to Central and South America—where the U.S. gets the vast majority of its bananas. The problem has gotten so bad according to the United Nations Food and Agriculture Organization, that countries that grow bananas have been warned to step up monitoring, reporting and prevention in order to tackle what it calls "one of the world's most destructive banana diseases, and threatens the income of millions of people."

According to the FAO, bananas are the eighth most important food crop in the world and the fourth most important food crop among the world's least-developed countries. Through trade and supply, bananas make up a global $8.9 billion trade industry.

Bananas are grown in more than 150 countries, which produce 105 million tons of fruit per year, while employing hundreds of thousands pf people. The U.S. is the top importer of bananas in the world at nearly 4 million tons a year. The European Union is a close second. The largest exporters of the fruit are Ecuador, the Philippines, Costa Rica, Guatemala and Colombia. Panama disease, or Fusarium wilt as it's also called, has been around for decades and can strike crops such as tobacco and tomatoes as well as bananas. Read MoreFarming in America: 'There's a growing discontent'

The TR4 strain, while not a danger to humans, is found in the soil and can remain active for decades, but it cannot be fully controlled by fungicides. The best way to fight the disease, according Ploetz, is to prevent its spread, which includes avoiding movement of diseased plant materials and infected soil. As for it coming to Central and South America, at least one analyst on the scene is not too worried at this point. "I see a lot of people stressed...and we're monitoring the situation, but I think it may be a bit overblown," said Lianne Zoeteweij, general manager of AsoGuabo, a banana farm cooperative in Ecuador. "We have concern yes, but I think the warnings of bananas disappearing is too much," she said in a phone call with CNBC.

New banana needed?