The effects of mild cacao swollen shoot virus strains N1 and SS365B on growth and yield of cacao

Abstract

A field experiment started at the Cocoa Research Institute of Ghana in 2007 to investigate the effects of the cacao swollen shoot virus (CSSV) mild stains N1 and SS365B on growth and yield of mixed hybrid cacao (Theobroma cacao L.). Growth was significantly influenced by the duration of infection with the two CSSV mild strains. Slicing analyses showed no significant differences in stem circumference among treatments up to the third year of field data collection. However, from the fourth to the seventh year, growth of N1-inoculated cacao plants was significantly higher than that of SS365B-inoculated plants. Overall, growth did not differ significantly between cacao plants inoculated with mild strain and the non-inoculated plants. Contrary to some previous reports, yield of mild strain-inoculated cacao plants was significantly lower than that of the non-inoculated plants. Polymerase chain reaction was used to detect the presence of CSSV in randomly selected field samples. The implications of these results (based on field data collected from 2008 to 2014) in the management of cocoa swollen shoot virus disease in Ghana are discussed.