Morphological and Molecular Identification of the Fungus Associated with Pink Disease of Cocoa (Theobroma cacao L) in the Eastern Region of Ghana

Abstract

The Pink Disease is caused by the fungus Erythricium salmonicolor (Berk & Broome) Burdsall. It attacks broad hosts such as cocoa, coffee, citrus Eucalyptus spp. and Acasia spp. An outbreak of similar disease symptoms on cocoa trees in the Eastern region of Ghana has been a threat to the cocoa industry. However, the organism causing the disease in the Eastern region of Ghana has not been properly identified. Therefore, objectives of this study were to identify the causal organism of the pink disease of cocoa in the Eastern Region of Ghana and to also determine the genetic variability among the isolates collected. All isolates produced salmon-pink fluffy mycelia with concentric zones and regular margins on (Potatoes Dextrose Agar) PDA and Malt Extract Agar (MEA). The hyphae were hyaline, thin-walled, joined to each other and with clamp-connections.  Amplification of the ITS region of isolates of E. salmonicolor using primers produced a 750 bp which is the expected fragment size. The isolates varied genetically with mean similarity of 55%.  Isolates from Saamang, Bunso and Osino communities related by 78% whiles Isolates from Osino and Bunso communities clustered together at 88% making them the most related among all the isolates.