Scientists of University Sains Malaysia (Penang, Malaysia) have detected firstly the reddish brown spot disease on dragon fruit in Malaysia. They collected stems of red-fleshed dragon fruit (Hylocereus polyrhizus) with reddish brown spots from Negeri Sembilan and Johor states, then analysed the symptomatic samples in terms of morphology and DNA sequences.
"The fungi isolated from the stems have been identified as Nigrospora lacticolonia and N. sphaerica, as the causal pathogens of the disease," the scientists report.
The size of conidia of N. sphaerica are relatively bigger than N. lacticolonia. The phylogenetic analysis of internal transcribed spacer region, β-tubulin and translation elongation factor 1-α genes have confirmed the two identified species, which result phylogenetically different. The pathogenicity test have confirmed that the fungal isolates produce reddish brown spot on the inoculated stems.
"This is the first report of N. lacticolonia and N. sphaerica as the pathogens of dragon fruit plant in Malaysia", the scientists conclude.
