The Banana Pandemic

In the past year, I think it’s pretty fair to say that we have all become a lot more cognizant of disease. The spread of coronavirus around the globe has opened our eyes as a society to the devastating effects microorganisms can have on ourselves and the ecosystems around us, and this pandemic is sure to have long lasting impacts looking forward. However, Covid-19 hasn’t been the only pandemic to rock the boat in 2020…

Say hello to Tropical Race 4 (TR4), the other microorganism to begin wrecking major havoc in 2020. Unlike the coronavirus, TR4 is a fungus, and its primary target is everyone’s favorite fruit: the banana (ok so maybe ‘everyone’s favorite fruit’ is a bit hyperbolistic, but you get the point). When TR4 infects a banana tree, it causes a nasty disease known as Fusarium wilt, aka Panama disease. As the disease progresses, the fungus colonizes and blocks off the vasculature of the plant causing the precious bananas to wilt and die. 

So what makes TR4 so bad? Afterall, there are millions of disease causing microbes out there, and not all of them cause massive epidemics. Well, there are a few key features that contribute to TR4’s success. First, when a plant contracts Panama disease, farmers can’t tell right away. Crops that have been infected don’t show signs of wilting and death for up to a year after exposure. By that point, the fungus has already likely spread through spores in the soil and on farmers’ boots and equipment. Secondly, TR4 spores are highly resistant, and they are able to lay dormant in soil for years after the plant has died. This means that new banana crops can’t be planted for decades after the disease rampage. Finally, the bananas have no defense against the fungus. It seems like science fiction, but all the bananas that we eat are actually clones of one another. The banana you know and love is a variety called the cavendish banana. Because of the way bananas reproduce, all of the banana plants around the globe are actually a part of the same plant forming the largest organism on the entire planet. Since these bananas continue to ripen after being picked, they have been a serious cash crop for the entire banana industry; however, the lack of genetic diversity means that all bananas are highly susceptible to TR4. And, worst of all, there is no cure.

Amazingly, this isn’t even the first time that this has happened. Back in the 1950s, the main variety of banana was called the Gros Michel. These bananas were said to have a sweeter, better taste. Unfortunately, they were nearly wiped out by a different fungal strain named TR1. This caused the banana industry to shift to the cavendish bananas we know today because of its immunity to TR1. Nowadays, the Gros Michel banana is only grown on small farms, and these bananas are highly expensive due to their rarity. 

Although it may not seem like a huge deal, the spread of TR4 poses serious threats to us as humans. The fall of the cavendish banana could crumble the entire banana industry leading to food shortages in South American countries. After the disease found its way into Brazil in 2019, the Columbian government declared a state of emergency due to the threat to one of its major industries. To combat the spread, Colombia imposed strict biosecurity measures such as quarantining farms and increasing sanitization practices (the equivalent of washing your hands and social distancing, but for bananas). However, the fungus continues to creep through the barriers and kill our crops. So, enjoy your banana smoothies while you can. Soon enough, they may be wiped out of existence.