Banana bunchy top virus (Babuvirus; Nanoviridae) detected in all banana growing districts of Malawi

By: Willard Mbewe, Andrew Mtonga, Pilirani Pankomera, Louis Mwamlima, Harold katondo, Antony Nyirenda, Frank Phukaphuka, Lucky Mataka, Harold Mbalame, Richard Thole, Vivian Kayira, Gama Bandawe,

Abstract

Banana bunchy top disease, caused by Banana bunchy top virus (BBTV), is a serious disease that affects the productivity of bananas globally. The disease is responsible for the current reduction of banana production in Malawi, and there are ongoing efforts to resuscitate the local banana industry. National surveys were conducted in 2020 and 2021 in eleven districts across all the three administrative and agricultural regions of the country to establish the current foliar incidence and the disease epidemiology. Foliar disease scoring and aphid population counts were recorded in 130 randomly sampled farmer’s fields. A total of 660 banana leaf samples were collected, and their total genomic DNA was extracted and amplified by polymerase chain reaction (PCR) using two gene-specific primers. The foliar disease incidences and severities varied across districts and variety types (p<0001). Disease foliar incidence was highest in Nkhata Bay district (93.33%) and lowest in Kasungu (0%). Molecular detection of confirmed the distribution of the disease in all the sampled districts, including Chitipa, which has for long been regarded as free from the disease and the sole source of clean planting materials for the country. Aphid populations were generally low with Karonga district having highest infestation score of 3 per field. The presence of the disease in Chitipa and subsequent increase in disease epidemiology possess serious threat to banana seed system and consequently food security in Malawi.