Scientists have decoded the complete genetic instruction manual for a fungus that causes a deadly disease in palm trees. The fungus, Fusarium oxysporum f. sp. palmarum, kills palm trees by causing one-sided leaf death that spreads upward through the canopy. By sequencing the fungus’s mitochondrial genome—the energy-producing part of its cells—researchers have created a tool that can help quickly and accurately identify this pathogen in infected plants. This discovery will help nurseries and gardeners detect and prevent the spread of this destructive disease.