Etiology of a gall disease of cocoa in Ghana caused by Calonectria rigidiuscula (Berk. & Br.) Sacc.

Abstract

SUMMARYA form or strain of Calonectria rigidiuscula (Berk. & Br.) Sacc. has been shown to be the cause of a gall disease of cocoa (Theobroma cacao L.) in Ghana. Galls were formed only when the pathogen was inoculated into buds, and the disease is not systemic.Seed is highly susceptible to infection, symptoms usually appearing 12–14 days after inoculation, and a rapid seed inoculation method for testing the pathogenicity of isolates from gall tissue is described. Galls on trees may not develop until many months after inoculation and the full extent of the latent infection period is not known.Using the same methods of inoculation, the disease could not be reproduced by isolates of the same fungus commonly associated with the disease‐complex referred to as ‘cocoa dieback’.