Pathogenicity of Colletotrichum species to Protea cultivars

Colletotrichum species cause a wide range of diseases on Proteaceae. Four Colletotrichum species, C. acutatum, C. acutatum f. sp. hakea, C. boninense and C. gloeosporioides, have been associated with diseased Proteaceae in South Africa. In this study, the pathogenicity of these taxa was evaluated on three Protea cultivars. The relative aggressiveness of the isolates and the effect that wounding had on the host response were compared. Results showed that C. boninense and C. acutatum f. sp. hakea did not cause lesions significantly different from those on the controls. Isolates of C. acutatum and C. gloeosporioides originating from Protea were the primary pathogens associated with Colletotrichum leaf necrosis. Furthermore, C. acutatum was the main cause of anthracnose and stem necrosis of the selected Protea cultivars tested.