Epidemiology and Diagnostics of Cacao Swollen Shoot Disease in Ghana: Past Research Achievements and Knowledge Gaps to Guide Future Research.

Cacao swollen shoot disease (CSSD) caused by complexes of cacao swollen shoot badnaviruses (family , genus ) remains highly prevalent and devastating in West Africa. The disease continues to impact substantially on cacao yield loss, cacao tree mortality, and decline in foreign exchange income from cacao bean sales. Currently, the disease is estimated to have a prevalence rate of over 30% in Ghana, as assessed in the ongoing third country-wide surveillance program.

Cacao Swollen Shoot Viruses in Ghana.

Cacao swollen shoot virus causes cacao swollen shoot disease of (cacao) plants. At least six cacao-infecting species-, (previously known as ), , , , and -are responsible for the swollen shoot disease of cacao in Ghana. Each of these species consists of a multiplicity of strains.

Field evaluation of the impact of cocoa swollen shoot virus disease infection on yield traits of different cocoa (Theobroma cacao L.) clones in Ghana.

Cocoa swollen shoot virus disease (CSSVD) is a major disease of cacao (Theobroma cacao L.) in Ghana and other West African countries that grow the crop. Attempts to develop resistant varieties since the discovery of the disease in 1936 have yielded little success.

Inconsistent PCR detection of Cacao swollen shoot virus (CSSV) is linked to the occurrence of different variants across the cocoa regions of Ghana.

Reliable diagnostic tools capable of detecting latent and asymptomatic infections are critically important to support the management of the cocoa swollen shoot virus disease (CSSVD) and also to complement research activities on screening for resistant cocoa varieties. Development of efficient polymerase chain reaction (PCR) assays sensitive for detection of CSSV infections has thus been a major research focus over the years. Advances in the full genome sequence information have resulted in the design of several Cacao swollen shoot virus (CSSV)-specific and degenerate primers.