Scientists in developing countries are scrambling to find a cure for a devastating fungus that threatens to wipe out the global banana trade and plunge millions of farmers into poverty.
Around the world, banana farmers are fighting a losing battle against Tropical Race 4, a soil fungus that kills Cavendish bananas, the only type grown for the international market. The disease was first spotted in the early 1990s in Malaysia, but has now started to wipe out crops in large parts of South-East Asia as well as in Africa and the Middle East.
The Tropical Race 4 pathogen, a new strain of what is known as Panama disease, escaped from Asia in 2013. By 2015, it had infected plantations in Jordan and Mozambique, as well as Lebanon and Pakistan, with many scientists fearing an epidemic in Sub-Saharan Africa.
“The impact on affected farms is immense, with significant losses of plants and the inability to eradicate the fungus from affected fields,” says Altus Viljoen, a plant pathologist at Stellenbosch University in South Africa.
The disease can be devastating for small banana farmers, who provide much of the 17 million tonnes of Cavendish bananas traded every year — mostly to rich countries where the fruit is popular as a healthy snack. Bananas are also a staple food in many tropical countries, and the main source of protein for more than half a billion people around the world.
In Indonesia and Malaysia, the fungus wiped out more than 5,000 hectares of Cavendish bananas in 1992/93, says Agustin Molina, who leads the banana research efforts in the Asia-Pacific region for Bioversity International, a global research organisation.
“The banana export trade in Malaysia and Indonesia failed to prosper because of Tropical Race 4,” he says. “Now tens of thousands of banana farmers in the Philippines, China and Taiwan could be affected.”
Molina and his team try to work with local farmers to raise awareness of the threat and contain the spread of the fungus. He advocates footbaths, regulating the movement of workers and tough quarantines for seedlings and other imported plant matter.
But despite such efforts, Tropical Race 4 has crossed the Pacific Ocean. With the fungus now in Mozambique, other East African countries largely dependent on Cavendish exports — such as Uganda — fear for their crop.
“If nothing is done in the next ten years, billions of dollars worth of crop will be lost,” says Enoch Kikulwe, an associate scientist at Bioversity International’s Uganda branch.
Uganda, the world’s third largest banana producer, imports second-hand trucks and farming equipment from China, but these are rarely disinfected before shipping — putting the country at risk. Likewise, Sudan exports bananas by lorry to Lebanon and Oman, while seedlings grown in Jordan or Pakistan are sold to Mozambique.