Mechanical transmission of cocoa swollen shoot virus to and from cocoa and other hosts

Cocoa swollen-shoot virus, hitherto transmitted only by mealybugs and grafting, was transmitted mechanically to cocoa from cocoa and eight other hosts. The virus was more readily transmitted from Adansonia digitata L. and Bombax brevicuspe Sprague than from the other hosts and most readily from B. brevicuspe. Transmission rates varied from 0 to 46 percent and rarely exceeded 5 percent. With a single exception, infective slurries were prepared only when the extracting fluid (pH 8-8.5) contained a reducing agent (cysteine, ascorbate, thioglycollate or sulphide) in addition to phosphate. Only cocoa half-beans and A. digitata seedlings have been infected mechanically; of these, cocoa half-beans were the more convenient test material.