TR4: will history repeat itself? - ProMusa blog" Looming large on the horizon is a new threat to African banana farmers: the tropical race 4 variant of Fusarium wilt (better known as TR4). TR4 was thrust into the limelight when it destroyed commercial Cavendish plantations in Malaysia and Indonesia in 1988. The killer fungus went viral (sorry) and spread to banana production areas in four more countries, including China. Once introduced, TR4 spreads rapidly with infected planting material, on contaminated tools, and in contaminated water and soil.