Incidence and Distribution of Banana Bunchy Top Virus in American Samoa

Banana Bunchy Top Virus (BBTV) was first reported in American Samoa in 1967. The incidence and distribution of disease, however, had never been established. In March 1999, five survey teams visually inspected approximately 30,000 banana mats at 20 villages and 10 commercial farms on the main island of Tutuila. Ten thousand mats were inspected on four other islands in the territory. The virus was present in all villages and farms surveyed on Tutuila. Average percent infection for 18 of the 20 villages was 3.4 ± 1.3% and for the 10 farms, 5.4 ± 3.7%. There was no apparent pattern of BBTV distribution. The small, offshore island of Aunu’u, had a 5.3% incidence of infection. No symptoms of BBTV were observed on the three islands of Ofu, Olosega and Ta’u, located 110 km east of Tutuila. Survey results were conservative, as only mats with moderate to severe symptoms of BBTV were considered diseased; more importantly, farmers tend to remove symptomatic plants and suckers as a means of disease control. The relatively low level of BBTV and its slow spread may indicate small populations or inactivity of the aphid vector, Pentalonia nigronervosa. A public information campaign and community-based management program is being developed. The latter will destroy infected mats with glyphosate and offer virus-tested tissue culture replacements. Survey results are encouraging for BBTV control in American Samoa.