First report of Colletotrichum tropicale on dragon fruit and the response of three Selenicereus species to anthracnose

Cultivation of dragon fruits (Selenicereus spp.) has health and commercial benefits, which are threatened by the presence of destructive diseases affecting this crop. In this study, a pathogenic isolate was obtained from a diseased stem of Selenicereus monacanthus (red peel, red flesh) in Luzon, Philippines. The causal agent of the disease was identified using combined morphological, cultural, pathogenicity, and molecular characterization. Colony and spore morphologies indicate that the pathogen belongs to the genus Colletotrichum. DNA sequences of the partial internal transcribed spacer, actin, glyceraldehyde-3-phosphate dehydrogenase, and beta-tubulin gene regions confirmed that the isolate was Colletotrichum tropicale. Anthracnose developed in S. undatus (red peel, white flesh) and S. monacanthus inoculated with C. tropicale. However, the isolate did not infect S. megalanthus (yellow peel, white flesh). To our knowledge, this is the first report of C. tropicale causing dragon fruit anthracnose. This study also provides evidence that resistance to anthracnose exists in the Selenicereus species. Because S. monacanthus and S. undatus have commercial significance, management strategies would be needed. Dragon fruit breeding programs using S. megalanthus as a source of resistance to anthracnose would be worthwhile.