Modeling the dynamics and transmission of cassava mosaic disease in Tanzania

Cassava mosaic disease (CMD) is caused by cassava mosaic virus (CMV) and is transmitted by the whitefly vector called Bemisia tabaci. In this paper, the deterministic model for transmission dynamics of CMD is formulated by considering the whitefly vector, cassava resistant and susceptible breeds, and infected cassava. The basic reproduction number $R_{0}$ and sensitivity index for each parameter with respect to basic reproduction number $R_{0}$ are computed to determine which parameters are sensitive to the dynamics of cassava mosaic disease. Analysis shows that the death rate of whitefly vectors, the infection rate for susceptible vectors, the number of vectors that can be supported and the rate of loss of infected cassava due to disease are the most sensitive parameters to the dynamics of cassava mosaic disease. Numerical simulation indicates that, cassava new infections increase as the number of vectors that can be supported increase and acquire cassava mosaic disease. It shows that if control measures are not considered, then the susceptible breed and cassava resistant breed will be wiped out after five and ten months respectively. To control the disease, farmers are encouraged to apply control strategies such as spraying of insecticide, using of vector-resistant varieties, phytosanitation which involve the removal of infected cassava plants from the farm, crop hygiene and the use of free stem cutting method.