A killer fungus is ravaging plantations of the Cavendish banana worldwide. It travels through the soil at lightning speed and chokes the banana plant so its leaves shrivel up and die. The disease is known as Tropical Race 4, or TR4 for short, and it has spread across the globe from Australia, to the Philippines, Pakistan and Mozambique. Now TR4 is widespread across Latin America. In Colombia where 30,000 people are employed in banana plantations, the government declared a state of national emergency when the fungus first arrived on farms in 2019. An international community of scientists is experimenting with different techniques to try to halt the spread of TR4 whether that's through gene-editing, selective breeding or injecting microbes into the soil.