A glass of orange juice in the morning is something many of us take for granted. But that might soon change thanks to a citrus disease affecting every major orange-growing region in the world.

The world's orange crop is being threatened by "citrus greening," a bacterial infection carried by a fly that feeds on citrus leaves.

Jack Payne, a senior vice-president of agriculture at the University of Florida, is leading the charge to find a cure in that state where citrus trees are being destroyed in large numbers.

In the science world, the condition is "better known as HLB which stands for huanglongbing, and the reason why it's become known as citrus greening is that once the tree succumbs to the disease, the fruit remains green," he explains.

"After about five years, the tree dies, and during that time you have less and less production, the sweetness never develops. It's a very sour-tasting fruit."

Citrus greening originated in China and made its first serious impact back in the 1940s and '50s. But the destruction then was largely regional, among producers in China and Taiwan.

Since then, the disease has spread across much of Asia and, over the past few decades, arrived in the North American and South American growing regions of Florida and Brazil.

Mandarins

Bacterial infection of orange crops in Florida has resulted in revenue and job losses. (Khalil Akhtar)

Payne says the results have been devastating in Florida where oranges have been the state's signature crop.

"This was first discovered in 2005. Our ag-economists at the university have estimated that since that time there has been a $4-billion loss in revenue to the citrus growers and 6,000 jobs lost."

Citrus greening has no known cure, apart from additional pesticide use to try to keep the flies away, and additional fertilizer use. But even those techniques haven't been completely successful, and only kept the disease at bay for a few seasons.
   
That's why Payne has been pursuing other avenues, like genetic modification to develop orange varieties that are resistant to the fly.

This week also saw the U.S. Department of Agriculture join the fight in earnest with the announcement that it is creating an "emergency response framework" to tackle the disease.

In the meantime, Florida is inching closer to significant agricultural change.

With 6,000 jobs lost and revenues down billions, oranges may not be the future in Florida. Increasingly, orange farmers are tearing out groves and replacing them with blueberries, strawberries and peaches.