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March 2000. The overwhelming evidence is that VSD is not seed borne. This was tested very thoroughly by Chris Prior at CCRI in Papua New Guinea. Also, the nature of the disease, being a vascular infection which rapidly kills infected shoots, makes it highly unlikely that (i) pods with viable seeds would ever be produced on infected branches (ii) the fungus would ever infect seeds on diseased shoots, even if pods were produced on them, and (iii) seeds, if they ever became infected, would be viable.
Even so, when CCRI sent seed to the North Solomons, the Institute took the added precaution of making sure pods were collected from healthy trees and unifected branches, seeds were extracted from pods and treated with a fungicide before being sent (packed in sawdust), and once in the North Solomons the seeds were germinated in a glasshouse and kept in quarantine until it was definite that they were healthy. Infection of very young seedlings results from inoculation with spores of the fungus shed onto the initial soft leaves, resulting in development of symptoms fairly quickly – within about 2 months – and then rapid killing of the seedlings. If seedlings get to 6 months old and look healthy, they could be planted out.
Another precaution, if cocoa germplasm were to be imported into Solomons Islands, would be to get the material from the North Solomons, which is free of VSD (CCRI has an experiment station there, but it is not known if it is still operating. It was used to import the best genotypes into North Solomons during the 1980s.
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