Chiang Mai Journal of Science

 In June 2021, brown spots was observed on Costa Rican pitahaya fruits (Hylocereus costaricensis) in a dragon fruit cultivation in Phatthalung province, southern Thailand. Infected dragon fruits showed small, circular, brown spots that expanded later to irregular shapes and the center of the symptomatic spot becoming dark brown with age. The fungus was isolated and cultured on potato dextrose agar (PDA) for morphological observation. Based on the macroscopic and microscopic features and phylogenetic tree of combined glyceraldehyde-3-phosphate dehydrogenase (gpd), internal transcribed spacer (ITS), and large subunit (LSU) sequences, this isolate was identified as Curvularia pseudobrachyspora. Pathogenicity tests by agar plug method revealed that this fungal isolate caused brown spot disease on Costa Rican pitahaya fruits with observations similar to the natural infection. To our knowledge, this is the first report of C. pseudobrachyspora causing brown spot disease on Costa Rican pitahaya fruits in Thailand.