The banana. A nutritious, affordable, and seemingly plentiful fruit that is ubiquitous in supermarkets across the globe. However, despite what the heaps of ripening yellow fruit in the produce aisle might suggest, the humble banana is under threat.
Although there are many banana varieties, the vast majority of bananas exported around the world are Cavendish bananas. Considering its worldwide status as “the” banana, it may surprise you to know that the dominance of the Cavendish came about due to the loss of the world's previous favorite banana.
During the first half of the 20th century, if you purchased a banana from a shop, it would have almost certainly been a Gros Michel (also known as “Big Mike”) banana. With a sweet taste and a thick skin that made it well-suited for long-distance transportation, the Gros Michel had come to dominate plantations in Central and South America, where they were mass-produced through cloning shoots.
However, the practice of monoculture left the Gros Michel vulnerable to a strain of soil-borne Fusarium fungus known as TR1. The fungus attacks the plant’s vascular system, resulting in Fusarium wilt, also known as Panama Disease. Despite efforts ranging from crop sprays to replanting in new fields, Gros Michel bananas were essentially wiped out by TR1 in the 1950s.
The popularity of the Cavendish banana can be traced directly to the loss of the Gros Michel, when the major fruit exporter United Fruit found a variety that was unaffected by TR1. However, the dominance of the Cavendish could someday be its downfall. Another strain of Fusarium (TR4) that can infect Cavendish bananas was first detected in the 1990s. However, despite this threat, the global banana supply chain depends almost entirely on the Cavendish. The continued use of monoculture and cloning plant shoots has resulted in TR4 spreading to more than 20 countries, despite efforts to quarantine infected fields. TR4 has already spread from Southeast Asia to Australia, the Middle East, Africa, and, most recently Latin America, the source of most exported bananas.
Preventing the banana apocalypse:
- TR4 is especially difficult to control because an infected plant can appear healthy for up to a year before its leaves begin to appear yellow and wilt. During that time, the disease could have spread to numerous other plants via soil carried by boots, farm equipment, plants, or animals. There is no cure for the disease.
- However, just as the Cavendish is resistant to TR1, other banana species are resistant to TR4. To improve the fruit’s resiliency against the fungus, researchers are investigating modifying the Cavendish with genes from a resistant species. However, with dozens of Fusarium strains in existence, this doesn’t necessarily mean the genetically-modified bananas will be safe.
- In a study published earlier this month in Nature Microbiology, researchers from the University of Massachusetts Amherst revealed promising findings that suggest we may be able to avoid a “banana apocalypse.” The researchers found that the damage from TR4 could be minimized by removing a specific section in the Fusarium genetic code linked to nitric oxide production.
- Ecologists widely agree that the best way to avoid a fungal pandemic destroying the world’s banana supply (and endangering the lives of people who depend on it as a food staple or for their livelihoods) is to cultivate a wider range of banana varieties, making them more resilient to disease. However, none have proven as suitable for long-distance export as the Cavendish and are far more expensive.
