One of the greatest challenges facing any plant quarantine centre is the detection of viruses since some virus species can remain latent for long periods or cause very mild or no symptoms in their hosts. The International Cocoa Quarantine Centre at the University of Reading (ICQC,R) uses an internationally accepted virus-indexing procedure developed to detect Cocoa Swollen Shoot Virus (CSSV), a disease that causes severe crop losses and tree death in many cocoa producing areas of West Africa. Clearly the spread of CSSV to additional cocoa growing areas would have very serious consequences for the whole of the global cocoa industry, thus underlying the importance of effective quarantine when moving live cocoa plant material into any cocoa producing country.
Although some mild cocoa viruses, that are distinct from CSSV, have been reported from areas outside of West Africa, the extent of their distribution has remained largely unknown. It has been difficult to confirm infections since these mild viruses cause few or no symptoms, or produce symptoms which are similar to those caused by some nutrient deficiencies. However, recent developments in molecular methods have allowed the recent detection of two mild strain viruses, Cacao Mild Mosaic Virus (CaMMV) and Cacao Yellow Vein Banding Virus CYVBV and have led to the discovery of these viruses in various locations (Puig et al. 2020; Puig 2021; Ramos-Sobrinho et al. 2021) including in the International Cocoa Quarantine Centre, Reading (ICQC,R) (Ullah et al. 2021).
The following Questions and Answers seek to provide clarity on the broader implications of this recent finding.