R. C. Ploetz, University of Florida, IFAS, Tropical Research and Education Center, 18905 SW 280th Street, Homestead 33031-3314; and X. Mourichon, CIRAD/FLHOR, Laboratorie de Phytopatologie Vegetale, 2477, avenue du Val de Montferrand, B.P. 5035, 34032 Montpellier Cedex 1, France. Plant Dis. D-1998-1217-03N, 1998 (on-line). Accepted for publication 15 December 1998.
Black Sigatoka, caused by Mycosphaerella fijiensis, is widely recognized as the most important disease of banana, Musa spp. It has spread rapidly in the Western Hemisphere since it first appeared in Honduras in 1972, and is now found in the Caribbean basin in Cuba, Jamaica, and Santo Domingo, and on the mainland from central Mexico south to Bolivia and northwestern Brazil (2). In October 1998, symptoms of black Sigatoka (2) were observed on several different cultivars in a collection at the University of Florida's Tropical Research and Education Center (TREC) in Homestead (25°30¢ N, 80°30¢ W). During preliminary surveys, the disease was found at four of eight locations in a 15 km2 area to the north of TREC. Disease severity, rated as the youngest leaf spotted (YLS), averaged 4.8 on the most susceptible cultivar, Rajapuri, at one of the locations. The extent and history of damage at this site indicated that black Sigatoka had been there for at least 3 to 4 years. The prevailing east to west winds in the Caribbean, and highly variable incidence and severity of the disease also suggested that the pathogen had been introduced to the area on infected seed pieces (suckers) rather than by wind or rainblown ascospores from Cuba or other affected areas (1). The presence of the disease was confirmed after the following characteristics of the pathogen's anamorph, Paracercospora fijiensis, were observied on affected leaves: simple conidiophores occurring singly or in groups of two to six with one to several septa, scars, and usually a broadened base; and conidia much more abundant on lower leaf surfaces, straight to variously bent with one to several septa and a conspicuous scar at the base. Single-ascospore cultures were recovered from Rajapuri and are stored at CIRAD/FLHOR in Montpellier. This is the first time black Sigatoka has been reported in the continental United States. Banana is a minor but significant tropical fruit crop in southern Florida, with fruit valued at over $2.5 million per annum. Production from Hua moa, Silk, and other important cultivars will probably be affected as the disease becomes established in this part of the state.
References:
1. R. H. Stover. Plant Dis. 64:750, 1980.
2. J. C. Tejerina et al. Plant Dis. 81:1332, 1997.
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