Download Nguyễn Thành Hiếu1, Nguyễn Ngọc Anh Thư1, Nguyễn Văn Hòa1

Nguyễn Thành Hiếu1, Nguyễn Ngọc Anh Thư1, Nguyễn Văn Hòa1
Identification of morphological and biological characteristics
of Neoscytalidium dimidiatum causing canker on dragon fruit
Abstract
At present, dragon fruit (Hylocereus undatus) is one of special fruit crop which occupies more
than 27,000ha in Southern of Vietnam. Unfortunately, stem canker (Neoscytalidium dimiatum) is
known as “white spot”, “brown spot” which attacked severely at different stages of plant and caused
serious problem in reducing yield (30 to 70%) from year 2011. Initial symptoms appear by many
small circular of pin prick on surface of cladodes or fruits, later they turn to white spot,
yellowish/reddish brown canker. Finally, the spots may coalesce to cover large areas of cladode and
infection may cause rot under favour conditions. This study was conducted to isolate, indentify and
characterize the fungal pathogen based on morphological and molecular characteristics,
pathogenicity test and evaluation of temperatures and pH effects to fungal growth rate under in vitro
conditions. A total of 56 isolates of samples (both cladode and fruit) were isolated an d identified as
Neoscytalidium dimiatum. For pathogencity test, all isolates of N. dimidiatum were pathogenic
causing stem canker on white flesh variety as the same symptoms appeared in the field conditions.
Several enviromental factors including temperature, pH were investigated on fungal pathogen. The
obtained results showed that optimal temperature of fungal growth ranging from 30 - 400C and
similarly, pH level from 4,5-8,0 un-effected mycelium growth of N. dimidiatum.