Researchers discovered that a wood-decay fungus called Trametes hirsuta is causing serious damage to avocado trees in Michoacán, México, the world’s largest avocado-producing region. The fungus infects tree trunks and branches, causing white rot that eventually kills the trees. About 60% of surveyed avocado trees showed signs of infection. Laboratory experiments confirmed that this fungus, previously known only as a decomposer of dead wood, can actively infect and destroy living avocado trees through wounds in the bark.