bananas

Your Favorite Banana Could Go Extinct Thanks To A Deadly Fungus

If you visit a grocery store’s produce section, there’s one fruit that you are almost definitely going to see: the banana. Bananas are a healthy fruit loaded with fiber, potassium, and other vitamins. [1] And chances are, whether you’ve eaten 10, 100, or 1,000 bananas in your life, you’ve eaten the same exact type of banana each time. Some of them are larger, some smaller, some greener and some riper. But they’re all the same banana. They’re called Cavendish bananas, and they may soon be a thing of the past.

The Cavendish banana is available in nearly every supermarket and is so widespread because it’s hardy and easy to cultivate. But it wasn’t always the “in” banana. In the 1950s, people ate a type of banana called the Gros Michel. It was similar to the Cavendish banana and enjoyed by many millions of people. But by the middle of the 20th century, Gros Michel bananas were wiped out by an insidious, deadly fungus – Fusarium oxysprum fungus. [2]

Fusarium oxysporum, sometimes called “Panama disease,” is a fungus that lives in soil and causes bananas to blacken from the inside out. Once Panama disease has infected a plantation, the fungus can completely destroy it in just a few short months. You can remove all of the bananas from the plantation, but because the fungus can survive in the soil for decades, it will simply re-infect future crops planted there.

Fusarium begins by invading the roots of banana trees, usually through a wound of some kind. From there, the fungus begins invading the rootstock and leaf bases. It spreads through vascular bundles which slowly begin to turn black. The leaves of the banana tree begin to turn yellow, wilt, and hang downward. Eventually, all of the aerial parts (above-ground parts) of the tree are dead. The tree itself is still alive and may even develop new growth, but eventually that dies as well. After a few years, the tree will eventually die, but the fungus can carry on for decades in the soil. [3]

Originally the Cavendish variety was considered a replacement for the Gros Michel because it was resistant to the fungus. However, a newer strain of the Fusarium fungus known as tropical race 4 (TR4) emerged approximately 50 years ago in South East Asia and has spread around the world [4]. This variety of Panama disease has been infecting Cavendish bananas, ravaging plantations throughout the world, namely Asia, Africa, and the Middle East. But the fungus had not made it to South America until June of 2019[4]. After being found in La Guajira, a northeastern province of Colombia, a national emergency was immediately declared to quarantine the disease. [5] In total, 421 acres of banana plantations were quarantined.

The situation with Fusarium fungus reaching plantations in South America is worsened by the fact that the Cavendish banana stems from just a single genetic clone, meaning the tree is essentially identical everywhere in the world. Most banana trees are sterile and grown clonally. Any monocrop is especially vulnerable to epidemics, and the banana is no exception. Fusarium is able to survive fungicides and fumigants that might control other infections, leaving effectively no defense for these especially vulnerable cultivars.

One of the only lines of defense for our beloved Cavendish bananas is creating a more genetically diverse tree that is resistant to Panama disease. There are over one thousand types of bananas that grow around the world, and there are many delicious alternatives to the Cavendish. However, there may ways to save it by creating a more genetically diverse banana. Scientists could achieve this by creating a Cavendish banana tree that is resistant to Fusarium oxysporum.

Read: Blue Java Banana: The Banana That Tastes ‘Just Like Vanilla Ice Cream’

Another possibility would be engineering a new Cavendish banana by sequencing the genome of the banana tree and creating a new tree resistant to Fusarium. But that opens the door to new, unforeseen problems, like the inability to resist other types of infections.

Panama disease is currently at bay in South America, but the question is much less if but when it surfaces again. Sometime in our lifetimes, much like the Gros Michel banana, our beloved Cavendish banana may be a thing of the past.

  1. https://www.webmd.com/food-recipes/health-benefits-bananas#1
  2. https://www.frontiersin.org/articles/10.3389/fpls.2019.01395/full
  3. https://www.britannica.com/science/Panama-disease
  4. https://www.nature.com/articles/s41598-020-58378-9
  5. https://www.independent.co.uk/news/world/americas/colombia-banana-crops-panama-disease-spread-emergency-fungus-tr4-latest-a9055661.html
Thomas Nelson
Environmental Advocate
Thomas is an Oregon-based environmental advocate, a lover of the outdoors, and has an at times unhealthy obsession with chickens.