killing the entire leaf. Starved for energy, fruit production falls by 50% or more, and the bananas that do grow ripen prematurely, making them unsuitable for export. The fungus has shown ever-increasing resistance to treatment, with the current expense for treating exceeding US$1,000 per year. In addition to the expense, there is the question of how long intensive spraying can be environmentally justified. Banana bunchy top virus Banana bunchy top virus (BBTV) is a plant virus of the genus Babuvirus, family Nanonviridae affecting Musa spp. (including banana, abaca, plantain and ornamental bananas) and Ensete spp. in the family Musaceae. Banana bunchy top disease (BBTD) symptoms include dark green streaks of variable length in leaf veins, midribs and petioles. Leaves become short and stunted as the disease progresses, becoming 'bunched' at the apex of the plant. Infected plants may produce no fruit or the bunch may not emerge from the pseudostem. The virus is transmitted by the banana aphid Pentalonia nigronervosa and is widespread in SE Asia, Asia, the Philippines, Taiwan, Oceania and parts of Africa. There is no cure for BBTD, but it can be effectively controlled by the eradication of diseased plants and the use of virus-free planting material. No resistant cultivars have been found, but varietal differences in susceptibility have been reported. The commercially important Cavendish subgroup is severely affected. Banana bacterial wilt Banana bacterial wilt (BBW) is a bacterial disease caused by Xanthomonas campestris pv. musacearum. After being originally identified on a close relative of bananas, Ensete ventricosum, in Ethiopia in the 1960s, BBW occurred in Uganda in 2001 affecting all banana cultivars. Since then BBW has been diagnosed in Central and East Africa including the banana growing regions of Rwanda, the Democratic Republic of the Congo, Tanzania, Kenya, Burundi, and Uganda. Conservation Given the narrow range of genetic diversity present in bananas and the many threats via biotic (pests and diseases) and abiotic (such as drought) stress, conservation of the full spectrum of banana genetic resources is ongoing. Banana germplasm is conserved in many national and regional gene banks, and at the world's largest banana collection, the International Musa Germplasm Transit Centre (ITC), managed by Bioversity International and hosted at KU Leuven in Belgium. Musa cultivars are usually seedless, and options for their long-term conservation are constrained by the vegetative nature of the plant's reproductive system. Consequently, they are conserved by three main methods: in vivo