Coconut (Cocos nucifera) is a high economic value cash crop in Malaysia. In December 2021, irregular spots with dotted rust-like appearance were observed mainly on the tip of the leaves of MATAG variety coconut seedlings at the nursery in Perak state. More than 90% of the surveyed coconut seedlings exhibited leaf spot symptoms. These symptoms could cause huge economic losses because of the downgraded value of the seedlings. Fifteen symptomatic leaves were isolated on potato dextrose agar (PDA). A total of four single-spore isolates were obtained and observed morphologically. The isolates had white cotton-like appearance with an undulate edge. Black acervuli were produced after 7 days of incubation at 26°C. Conidia were fusiform and contained five cells with four septa and three versicolor cells in between the apical and basal cells. The conidia were 17.2 μm long and 5.9 μm wide (n = 30). The conidia consisted of two to three apical appendages and one basal appendage. Species identification was done by amplifying the internal transcribed spacer (ITS) region using the primers ITS 4 and ITS 5 and beta-tubulin (TUB2) using the primers Bt2a and Bt2b. The 488-bp ITS and 409-bp TUB2 sequences were deposited in GenBank under the accession numbers ON844193 and OP004810, respectively. The isolate LKR1 shares 99.8% identity with the ITS sequence (MH860736.1) of the reference pathogenic N. clavispora strain CBS 447.73 and 100% identity with the TUB2 sequence (KM199443.1) of the reference pathogenic N. clavispora strain CBS 447.73. The pathogenicity test was conducted using five replicates of 8-month-old seedlings, which were incubated under greenhouse conditions. After a month, signature symptoms of spots on the leaves appeared but none on the control seedlings. To our knowledge, this is the first report of N. clavispora causing leaf spot disease on coconut seedlings in Malaysia. Through the identification of N. clavispora as the causal agent of leaf spot on coconut, this can help coconut growers tackle the disease problem earlier, thus preventing the disease from spreading until the adult phase.

Leaf spot symptom caused by Neopestalotiopsis clavispora on Cocos nucifera seedlings

Dayana Chong, Wael Alsultan, Syazwan Ariff, Lih-Ling Kong, Chai-Ling Ho and Mui-Yun Wong (2023). First Report of Neopestalotiopsis clavispora Causing Leaf Spot on Coconut Seedling in Malaysia. Plant Disease.

Artikel penuh: https://doi.org/10.1094/PDIS-04-23-0636-PDN

Tarikh Input: 31/10/2023 | Kemaskini: 31/10/2023 | ainzubaidah