First Outbreak of Banana Streak Badnavirus Infection in Commercial Export Bananas in Costa Rica

Banana streak badnavirus (BSV) is the most widely occurring virus in banana and plantain (1) but has not been reported to be a significant problem in commercial export bananas. In early 1999, the first severe outbreak of BSV infection in commercial export bananas (Musa AAA cv. Grand Nain) was recorded at Siquirres on the Atlantic coast of Costa Rica. Disease incidence in the plantation was 60% and symptoms included foliar chlorotic streaks, stunting of plants, splitting and internal necrosis of pseudostems and fruits, cigar leaf necrosis, and bunch emergence through the pseudostem. Diseased plants within a 0.8 ha area were eliminated to prevent possible further spread of the disease. The presence of BSV in diseased plants was confirmed by enzyme-linked immunosorbent assay and immunosorbent electron microscopy (1). Cucumber mosaic virus and Banana mild mosaic virus, which also occur in banana and plantain in Latin America (2), were not detected in the plants tested. Other recent accounts of BSV occurrence in commercial banana plantations in South America (our unpublished results) suggest that BSV occurrence in export bananas may be more significant than previously thought. References: (1) F. Gauhl et al. Int. J. Pest Management 45:167, 1991. (2) D. R. Jones, ed. 1999. Diseases of Banana, Abacá and Enset. CABI Publishing, Wallingford, U.K.

Banana Streak Badnavirus and Cucumber Mosaic Cucumovirus in Farmers' Fields in Zanzibar

Symptoms resembling those of viral leaf streak disease, caused by banana streak badnavirus (BSV), were observed in May 1998 on two banana (Musa spp.) landraces grown from farmer-collected propagules in a farmer's field at Kiboje Uchukuni, Zanzibar. Those showing symptoms were “French plantain” cv. Mzuzu and “Cavendish” banana cv. Mtwike. Leaf symptoms were expressed as chlorotic streaks and blotches. Leaf samples were indexed by immunosorbent electron microscopy with BSV and cucumber mosaic cucumovirus (CMV) antibodies, using partially purified preparations (2). The two landraces tested positive for BSV, corroborating the occurrence of BSV in Zanzibar. In addition, cv. Mtwike was found to be coinfected with CMV. No other viruslike particles were seen by electron microscopy. Although BSV has been reported in Zanzibar (1), it was only from symptoms in the Musa field genebank at Kizimbani Research Station. BSV has been found in many Musa collections worldwide, particularly in the widely grown cv. Mysore. This report confirms the presence of BSV in farmers' fields and is also the first report of CMV infecting banana in Zanzibar. References: (1) A. J. Dabek and J. M. Waller. Trop. Pest Management 36:157, 1990. (2) M. Diekmann and C. A. J. Putter. Musa spp. FAO/IPGRI Technical Guidelines for the Safe Movement of Germplasm No. 15. FAO/IPGRI, Rome, Italy, 1996.