Sooty blotch and flyspeck on mango (Mangifera indica L.) caused by Peltaster-like species in Malaysia

Fungi in the sooty blotch and flyspeck (SBFS) disease complex appear as pigmented blemishes on plant cuticles and are commonly observed on several fruits, including mango. In Malaysia, SBFS on mango has not been reported previously. However, SBFS symptoms were observed in commercial mango orchards in Perak, resulting in economic losses for sale of fresh fruit. Therefore, morphological, molecular, and pathogenicity studies were conducted to identify SBFS taxa on mango in Perak. A total of 27 mango fruit showing SBFS blemishes were collected from several commercial orchards in Perak. Colony morphologies were described on fruit and in purified culture, and DNA was extracted from the cultures. The internal transcribed spacer (ITS) and large subunit (LSU) regions of ribosomal DNA of two representative isolates were amplified, sequenced, and deposited in GenBank. Maximum parsimony (MP) and maximum likelihood (ML) methods were used to construct phylogenetic trees. A modified version of Koch's postulates was performed for the two isolates using unripe, asymptomatic fruit with two inoculation methods: in situ in an orchard and on excised fruit. In each case, two fruit per isolate were inoculated and two additional fruit were sprayed with distilled water as a control. For the in situ inoculation, an additional two non-inoculated fruit were enclosed in bags until harvest. The colonies resulting from the inoculation of mango fruit matched the original isolates in mycelial type and ITS sequence. Two previously unknown Peltaster-like species were identified as casual fungi of SBFS on mango in Malaysia. To increase management effectiveness, more extensive research on SBFS phylogenetic diversity in Malaysia should be conducted.