ISSN 2375-1231
African Journal of Crop Science ISSN: 2375-1231 Vol. 9 (10), pp. 001-010, October, 2021. © International Scholars Journals
Full Length Research Paper
Changes in the epidemiology of cassava brown streak disease and associated viruses in Rwanda: occurrence and distribution since 2009
G. Gashaka1. M.C. Kanyange1. M. Mutumwinka1. G. Niyonteze1. J. Umfuyisoni1. A. Nduwumuremyi1. J. P. Bizimana1. F. Tairo 2. P. Sseruwagi2 and J. Ndunguru3
1Rwanda Agriculture and Animal Resources Development Board, P.O. Box 5016 Kigali, Rwanda. Corresponding Author: G. Gashaka: [email protected]
2Mikocheni Agricultural Research Institute, P.O. Box 6226 Dar es Salaam, Tanzania.
3Tanzania Agricultural Research Institute Selian, P.O.Box 6024 Arusha, Tanzania.
Accepted 13 July, 2021
Abstract
Cassava brown streak disease (CBSD), the most important viral disease of cassava in Africa is caused by two ipomoviruses, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Field surveys were conducted in 2009, 2013, 2015 and 2017 to determine the incidence and severity of CBSD in major cassava growing districts of Rwanda. Farmers’ fields were assessed and leaf samples collected for virus detection using RT-PCR. Results showed that the disease occurred in Southern province with an average incidence of 60.8% and severity of 2.5, Eastern province with 39.2% and 2.5 and Western Province with 22.2% and 3.2. The highest incidence was recorded in Southern Province (60.8%) and the lowest in Western Province (22.2%). The mean severity ranged from 2.0 to 2.8 on the surveyed cassava plants. RT-PCR detected both CBSV and UCBSV species, which occurred in single CBSV (10%), UCBSV (9.6%) and dual CBSV + UCBSV (1.6%) infections. The study showed the widespread occurrence of CBSD, its severity and the associated viruses in Rwanda. It highlights the urgency of implementing effective control measures to avert the impact of the disease on the food crop that feeds most households in the country.
Keywords: Cassava, CBSD, CBSVs, incidence, severity and epidemiology.