Status of cassava mosaic begomoviruses in farmers’ fields in Ghana

Abstract

A survey for cassava mosaic disease (CMD) was carried out in Ghana from 2007−2008 to determine the status of cassava mosaic begomoviruses in farmers’ fields. The survey covered cassava growing areas in five major cassava producing regions of Ghana. Out of 136 fields visited, the plants in 5% were not affected by CMD, 18% contained plants with mild symptoms, whereas 77% had cassava with moderately severe or severe symptoms. A total of 412 cassava leaf samples and a symptomatic Manihot glaziovii sample were analyzed using polymerase chain reaction. African cassava mosaic virus (ACMV) alone was detected in 42.0% of symptomatic cassava leaves with the remaining 58% being mixed infected by ACMV and East African cassava mosaic virus (EACMV). Mixed ACMV and EACMV infections were detected in symptomatic M. glaziovii, two non-symptomatic cassava samples and in individual whitefly vectors. EACMV was not detected alone in any cassava or whitefly sample. South African cassava mosaic virus (SACMV), Indian cassava mosaic virus (ICMV), East African cassava mosaic Zanzibar virus (EACMZV) and the Uganda strain of EACMV were not detected in any cassava or whitefly sample. The occurrence of high proportion of mixed infections of cassava by cassava mosaic begomoviruses (CMBs), which could lead to emergence of new species or variants in the country, require concerted effort to mitigate the CMD problem.