Black Sigatoka, which is also known as black leaf streak, is caused by Mycosphaerella fijiensis (anamorph Pseudocercospora [formerly Paracercospora) fijiensis]). It is the most important disease of commercially produced banana (Musa spp.) and also has a major impact on production for local consumption. Although the disease occurs throughout the humid tropics, it has been reported in the Caribbean from only Cuba, Hispaniola, and Jamaica (1). In February 2004, black Sigatoka was observed at two isolated and widely separated sites on Grand Bahama island (26.7°N, 78.5°W and 26.7°N, 78°W) on cvs. Silk AAB and Williams AAA, and a French Horn AAB plantain. Symptoms included wet, dark brown streaks on the adaxial leaf surface, 1 to 2 × 10 mm, with chlorotic haloes. Lesions enlarged to 5 × 20 mm and developed tan, necrotic centers; large, blackened, water-soaked areas that resulted from the coalescence of streaks were rare. The disease was confirmed by observing the following characteristics of P. fijiensis in necrotic lesions on preserved leaf specimens: simple conidiophores with a broadened base and one to several septa, straight to variously bent cercosporoid conidia as much as 100 μm long with two to several septa, and a conspicuously thickened scar at the base. Both plantings were several years old and new planting material that could have been infested with the pathogen had not been introduced since their establishment. Symptoms were not severe and were distributed sporadically in both locations. The disease was not observed at the only other large planting of banana on the island (26.6°N, 78.6°W). The sporadic and apparently new infestations of two of three banana plantings on the island suggest that the pathogen may have arrived recently via natural means, possibly from neighboring Florida (2). In contrast, black Sigatoka appears to have spread to other islands in the Caribbean via infested propagation materials (1). To my knowledge, this is the first report of black Sigatoka in the Bahamas, and with a previous report from Bhutan (1), represents the northernmost spread of this important disease.
References: (1) J. Carlier et al. Pages 37--79 in: Diseases of Banana, Abacá and Enset. D. R. Jones, ed. CABI Publishing. Wallingford, UK, 2000. (2) R. C. Ploetz and X. Mourichon. Plant Dis. 83:300, 1999.
