Plantain and banana (Musa spp.) are major staple and income-generating food crops in Africa that are largely produced on smallholder farms with yields remaining far below the potential, largely due to persistently high pest and disease pressures and declining soil fertility.
Banana bunchy top disease (BBTD) is one of the most serious threats to plantain and banana production. The global disease is caused by banana bunchy top virus (BBTV genus Babuvirus, family Nanoviridae) and has been reported in 14 African countries. The disease is spreading rapidly as it has invaded two countries in West Africa: Bénin and Nigeria, in the last three years. The disease is of serious economic concern as plants infected early in their growth do not produce fruit, resulting in total yield loss. Plants infected at later stages may produce normal or deformed fruits but the ratoon crop (the second bunch after the bunch produced by the mother plant) will bear fruit. IITA in collaboration with national and international partners has been conducting research – largely in West and Central Africa where nearly 90% of the world’s plantain are produced – with emphasis on understanding the virus and vector diversity, disease epidemiology, plant-virus-vector interactions, and factors affecting vector abundance for the purpose of developing economically and ecologically-based options for the sustainable management of BBTD.
In an on-going experiment in an infected area in southern Cameroon, we have so far followed the development of the disease and the population of the aphid vector of the causal agent for more than two years using 16 Musa genotypes. Symptom expression of BBTD varies widely among the genotypes without any specific patterns related to their genomic composition. The dessert banana Williams and the hybrid plantain PITA 23 were the most susceptible (at nearly 95% infection). A larger group including local plantain landraces, several hybrid plantains, the cooking banana FHIA 25 and the dessert banana Grande Nain were moderately susceptible. The least susceptible group contained only two genotypes, the dessert banana Gros Michel and the cooking banana Fougamou or Pisang Awak that had less than 10% infection after 27 months. In contrast, aphid vector populations followed a predictable pattern of increasing abundance with the presence of the B genome. These findings represent the first experimental evidence of the susceptibility to BBTD and aphids in local and hybrid plantain and cooking banana used in West and Central Africa and provide a basis for the selection of Musa genotypes in which BBTD disease develops slowly.
These genotypes can be combined with other management measures, such as the use of disease-free planting material as well as vector control for sustainable BBTD management in sub-Saharan Africa. IITA and Bioversity International, in collaboration with local and international partners, will convene a scientific meeting in Arusha, Tanzania, in February 2013 to build a collaborative, public-private R4D alliance to address BBTV in sub-Saharan Africa.