Black sigatoka (Mycosphaerella fijiensis) is the most severe disease affecting banana (Musa spp.) cultivars in terms of economic importance in the world. It was verified in Brazil in 1998, in the state of Amazonas, and has since spread throughout the state of Acre, severely attacking the cultivars of the Subgroup Plantain (AAB). This study was performed to diagnosis the occurrence of black sigatoka and the economic impact caused by the disease in the municipal districts of Acre. Visits to 16 municipal districts were made and samples of banana leaves with characteristic symptoms of the disease were collected for diagnosis. Black sigatoka was verified to be present in all municipal districts visited. The economical consequences of the disease are shown in a 42% reduction in total banana production in the State of Acre between 2000 and 2001, while the banana production fell another 47% in 2001, creating repercussions for diverse segments of the productive chain. Plácido de Castro and Acrelândia municipal districts were observed to have suffered the worst effects of black sigatoka.
