Mar. 8, 2018
Bananas are beloved: a standard in the kitchen, an on-the-go lunchtime snack, and for many, a dessert. In the modern world, it’s hard to imagine life without them. Cavendish bananas, which are the world’s standard, represent the fourth-most valuable global agricultural product after rice, wheat and milk. Grown in more than 130 countries, bananas are a staple food for more than 400 million people. The fruit is rich in nutrients, such as vitamin B, vitamin C, fiber and magnesium – making it a healthy snack before sports or simply between meals.
But this popular fruit is under serious threat. A new aggressive strain of the fungus causing Panama Disease, called Tropical Race 4 (TR4), is increasingly threatening banana farms worldwide. “Currently, the disease affects mostly bananas grown in the Philippines and China,” says Kai Wirtz, Global Crop Manager Fruit at Bayer’s Crop Science division in Monheim, Germany. “Further hotspots are in Malaysia, Indonesia, Australia and East Africa. Just recently, farmers have detected the Panama Disease in Israel.” Wirtz expects the disease to spread further west to other important banana production regions, especially Latin America. “It’s just a matter of time,” he adds. In fact, without counteraction against Panama Disease, there’s a chance that bananas could die out.
The fungal threat
Professor Gert Kema inspects a banana plant.
Fusarium wilt, popularly known as Panama Disease, is a lethal fungal disease caused by the soil-borne fungus Fusarium oxysporum. Once the disease has infested a plantation, the fungus can remain in the soil for decades. “The resting spores or chlamydospores of this fungus have very thick walls, which makes them tolerant against drought and even extreme weather conditions,” explains Professor Gert Kema, Chair of Tropical Phytopathology at Wageningen University and Research. “In contrast to Black Sigatoka, the other important fungal threat for bananas, there are currently no validated, commercial products on the market to control Panama Disease though the fungus is sensitive to a range of chemistries,” Kema adds. “The main topic will be how to get the fungicide in contact with the devastating fungus, particularly in soils. Therefore, the mode of application is a very important area for research, too.”
One Philippine farm recently affected by the Panama Disease is the Marsman Estate Plantation. “A few years ago, the Panama Disease infested some of our affiliate farms,” says Jeorge T. Yamuyam, a supervisor and researcher for the Crop Protection Cluster at the plantation. “Rapidly, our bananas turned black. The disease blocked the crops’ vascular system. Hence, the crops couldn’t produce any fruit.”
“As a result, we had no other choice but to incinerate our crops. We lost a huge amount of income,” he continues. “To protect our other farms, we focus on optimizing soil quality. For example, we add beneficial microorganisms to create a healthy living soil environment that seemed equipped against diseases such as the Panama Disease,” explains Yamuyam.
If this disease spreads more widely, serious economic consequences will result. The FAO states that the global banana trade is worth approximately seven billion US dollars. Consequently, the loss of banana production would mean an enormous loss of income for farmers, especially for the smallholders who cultivate 90 percent of the global banana production. Historically, this is a resurgence of the Panama Disease. Until the 1950s, the world’s dominant banana cultivar was “Gros Michel” – but this banana was decimated by other strains of the Panama disease fungus, known collectively as “Race 1”.
In the 1950s, banana supplies dwindled worldwide. Ultimately, an entirely new clone, the Cavendish, came to replace the Gros Michel variety. While it was said to be inferior in taste and bruise-prone, Cavendish bananas gave the world this fruit again. But since the 1990s, even the Cavendish is under threat as it is very susceptible to TR4, which was first discovered in South East Asia. Currently, there is no curative solution against this disease.
In order to save this important crop, Juan Aycart, a Research Senior Manager at Dole, one of the world’s leading banana companies, stresses the importance of a multidisciplinary, collaborative approach between all parties in banana exporting countries – and also within the scientific community. “From my recent participation in the Fusarium Workshop in Kansas, I learned that trust and respect between all participants of research focus groups are crucial to moving collaborative initiatives forward,” he says.
Fortunately, many researchers are already joining forces to fight back. One approach is to develop more disease-resistant varieties. “For example, we identify disease resistance genes from wild bananas to deploy them into edible bananas to make them stronger,” explains Professor Gert Kema. Additionally, Kai Wirtz and a team of Bayer scientists work on the development of new anti-fungal substances that can complement the fight against the Panama Disease and prevent further spreading. “Hopefully by 2019, we can introduce new products into the market,” adds Wirtz.
Bayer also wants to help farmers with preventive and practical approaches. New projects have been created, such as those in Ecuador, the world’s leading banana export country. “Together with local growers, we established hygiene measure guidelines,” explains Wirtz. “For example, next to fencing in the farms, growers set up quarantine areas in which they drive their cars through baths to wash off possible pathogen spores of the Panama Disease fungus. They also do the same with their shoes.”
If banana experts, scientists and farmers continue to join forces to find effective solutions to fight against the Panama Disease, there is hope that people worldwide can continue to enjoy the tasty and nutritious fruit.