By Roberta Attanasio
The world loves bananas. Actually, the world loves the Cavendish bananas, mostly because it is (almost) the only variety commercially available worldwide. The entire global banana industry relies on this seedless and, therefore, sterile variety made of bananas all essentially identical to each other — and equally susceptible to infection by the same harmful microbes, which can spread very easily across plantations around the world. This is not a hypothetical scenario — instead, it’s happening as we speak.
Two species of fungi are threatening the world supply of the Cavendish bananas. One is Mycosphaerella fijiensis, a fungus that causes a disease dubbed Black Sigatoka, also known as black leaf streak. According to the Food and Agriculture Organization of the United Nations (FAO), “Black Sigatoka spread from Asia and reached the Caribbean in 1991. Smallholder banana farmers were unable to shoulder the expense of fighting the disease on their own, and banana farms have been decimated.”
The other species of fungi, Fusarium oxysporum f. sp.cubense (Foc), causes Panama disease. A new strain of this fungus — Foc Tropical Race 4 (Foc-TR4) — is spreading to other regions of the world. In December 2013, the journal Nature published in its News section an article on this strain “Fungus threatens top banana – Fears rise for Latin American industry as devastating disease hits leading variety in Africa and Middle East.” Foc-TR4, which was first detected in Asia in the 1990s, is found in Taiwan, Indonesia, Malaysia, the Philippines, China and northern Australia and has very recently spread to Jordan and Mozambique.
One of the current solutions to the problem only adds another problem — enormous amount of fungicides are sprayed over plantations, causing serious human health concerns. As the fungi becomes resistant to them, larger and larger amounts of fungicides are needed to control the diseases.
There are more than 1000 varieties of bananas — at least this is the information you find by surfing the web. I haven’t been able to come upon an original, reliable source that confirms this number, but perhaps I haven’t looked well enough. Let’s just say that there are many varieties of bananas. So, why is the Cavendish banana found in 95% of the world’s market? According to the FAO, “Today’s commercial banana industry relies almost totally on the Cavendish because marketing only one variety makes harvesting, packaging and transport more cost-effective and delivers a uniform product.”
We do not seem to learn from history — the Cavendish variety was adopted by the commercial industry because it was resistant to a previous strain of Fusarium oxysporum f. sp.cubense. This strain also caused the aptly called Panama disease and in a few decades spread from Panama to other countries. By the 1960s, it had wiped out the banana variety Gros Michel, also known as Big Mike, which was grown in South America and Africa and was the dominant export banana to Europe and North America for the first half of the 1900s.
Now, the Cavendish banana is succumbing to either the new Panama disease or to Black Sigatoka.