Coloured scanning electron micrograph (SEM) of Fusarium oxysporum f.sp. cubense hyphae (yellow) in banana (Musa sp.) leaf tissue. This fungus causes Panama disease of bananas. It has caused significant damage to commercially grown cultivars of banana throughout the world since it was first reported in Australia in 1876. The most common bananas now grown for export, the Cavendish bananas, are resistant to the Race 1 subtype of F. oxysporum, but are extremely susceptible to the Tropical Race 4 (TR4) subtype. TR4, which was previously only found in South East Asia, has spread to Australia and Colombia and threatens global banana production. Infected banana tissue provided by Fernando Garcia-Bastidas, Keygene and Wageningen University, The Netherlands. Magnification: x100 when printed at 15cm wide.