Fruit and stem rot of pitaya (H. undatus and H. costaricensis) were observed in commercial planting areas in Okinawa Prefecture, Japan, in August 2002 and September 2007. Ash black to black or brown rot with pycnidia on the fruit surface and small circular sunken reddish brown or brown spots developed into cankers with many pycnidia on the surface of the stems and subsequently rotted. A fungus frequently isolated from damaged fruits and stems was identified as Neoscytalidium dimidiatum based on its morphological characters, pigment production, and molecular phylogenetic analyses. The fruits and stems were inoculated with the pathogen, the original symptoms were reproduced, and the fungus was re-isolated from the diseased fruits and stems. Disease caused by this fungus has not been previously reported in pitaya in Japan. We proposed the name “dry rot (kampu-byo in Japanese)” for this disease.
Taba et al. (Tue,) studied this question.