Tropical race 4 (TR4) is the latest race of the fungus Fusarium oxysporum f. sp cubense. It is a soil-borne pathogen that attacks the roots of the banana causing the Banana Fusarium Wilt disease by clogging its vascular system.

The fungus spreads through infected plant materials and contaminated soil particles attached to items such as farm tools, shoes, clothes, animals and vehicles. Irrigation and drainage water also play a critical role in its spread. Typhoons and other storms can also carry the TR4 fungus to new plantations. The survival form of the fungus, spores with a thick wall called chlamydospores, can remain dormant in the soil or on several host plants for decades.

The fungus affects many varieties including Cavendish bananas, which provide around half of global banana supply and almost all of the bananas exported. More than 80 percent of global banana production is thought to be based on TR4 susceptible germplasm. Once established in a field, TR4 can cause complete yield loss.

After the first detection in Asia in the 1970s of what would later become known as Tropical race 4 and its subsequent spread to Africa in 2013, TR4 arrived in Latin America in 2019—where around 2/3 of the global banana trade originates.

TR4 is recognized as one of the most aggressive and destructive fungi in the history of agriculture and the world’s greatest threat to banana production. The continued spread of TR4 would be devastating for the communities who rely on bananas for their livelihoods, but also sad for those who simply enjoy eating them. Bananas and plantains are critical to food security and livelihoods of around 400 million people.

The global food and agriculture system will need to undergo profound change if we are to nourish the 820 million people who are hungry today and the additional 2 billion people expected to be undernourished by 2050. Investments in agriculture, including banana sector innovation, are crucial to increase the capacity for agricultural productivity, while sustainable food production systems are necessary in achieving #ZeroHunger. 

Clearly, solutions in the form of effective resistance are urgently needed to avoid losses in a diverse array of sectors and communities. Research to breed TR4 tolerant or resistant varieties is being carried out by several institutions, but this takes time.

Currently, the most effective approach to combat TR4 is to prevent its spread to clean areas and to contain it as soon as it is detected.