Chiquita Brands International, the U.S.-based global produce company that’s perhaps best known for bananas — as well as for its catchy logo featuring the First Lady of Fruit — announced Monday that it would acquire Fyffes, its Irish rival. The two companies will become one before the end of 2014, making the new firm, ChiquitaFyffes, into the biggest producer and distributor of bananas in the world, with a $4.6 billion in annual revenue.

But sustainability experts worry that the merger will bolster the banana industry’s business model of selling a single variety of banana, which allows producers to better predict ripening time and create economies of scale. And that, they say, increases the possibility that a lethal fungus, Tropical Race 4 — which has already struck bananas in Asia, Africa and the Middle East — will destroy the world’s banana supply.

The average American eats an average of 27 pounds of bananas each year, according to Chiquita, already the world’s largest banana producer in a global export market worth $7 billion, according to Reuters. In fact, Americans eat more bananas than they do apples and oranges combined.

But what most banana lovers don’t know is that the fruit they usually see, cheaply and commonly bought at grocery stores around the globe, comes from a single variety called the Cavendish.

“Think of the banana not as a fruit but as a McDonald’s hamburger,” said Dan Koeppel, the Los Angeles–based author of the book “Banana: The Fate of the Fruit That Changed the World.”

Banana distributors chose to market a single type of banana because the fruit is perishable, Koeppel, who is currently working on a new edition of his book, told Al Jazeera. Because bananas are often shipped from plantations to consumers thousands of miles away, it made the most sense to pick one variety that would ripen uniformly to keep costs low.

So unlike, say, the apple market, which has diversified beyond just red or green, with dozens of varieties and price points available to shoppers, the banana market is dominated by the Cavendish, virtually the only variety sold in the U.S., even though there are more than a thousand kinds of bananas in existence, he said.

But the Cavendish, which originated in Asia, is not the same banana that was eaten a century ago. That banana of yesteryear was a variety called the Gros Michel, which Koeppel said was tastier than the Cavendish. It was also tougher; it could simply be hacked off the banana plant with a machete and haphazardly tossed into a train car without getting bruised, and it took a few weeks to ripen.