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<p><i>Calathea ornata</i> (Syn. <i>Goeppertia ornata</i>) (family Marantaceae), native to South America, is an evergreen perennial ornamental house plant that has economic importance for beautiful pale green variegated leaves with pin-stripe. In July 2023, leaf blight of Calathea was observed in greenhouse of The Neotia University, West Bengal, India that cause 10 to 50% leaf area damage. Initial symptoms of the disease were small, brown spots that appeared on the upper surface of leaves, which gradually enlarged and coalesced. These necrotic lesions spread to cover the entire leaf surface and ultimately caused leaves to shrivel and die. Under stereo-binocular microscopy, mycelial fragments along with fungal structures was observed on dead leaf portion. The associated pathogen was isolated from the symptomatic leaves and pure culture was obtained on potato dextrose agar (PDA) media. Conidia observed on diseased tissue were multicelled with protruding hilum at the base, terminal cells thickened, olivaceous or brown, fusiform in shape with blunt tips, 5 to 11 septate and 6 to 11 septate on culture media, measuring average of 97 × 12&#xa0;μm (n = 50) on diseased tissues and average of 96 × 11&#xa0;μm (n = 50) on PDA, germinating by producing germ tubes semi axially from each end. DNA was extracted from mycelia of a representative fungal isolate (ER01) by following CTAB 2% method and two gene regions (ITS and <i>GAPDH</i>) were amplified and sequenced. Phylogenetic study revealed that our isolate closely related to <i>Exserohilum rostratum</i>. Additionally, pathogenicity test was conducted by conidial spray and disc inoculation method, which confirmed the pathogenic nature of <i>E. rostratum</i> on <i>C. ornata</i>. Based on cultural, morphological, molecular characteristics and pathogenicity test, the pathogen was identified to be <i>E. rostratum</i>. As the disease may lead to death of foliar part of the plant under adverse conditions, this study might be helpful in proper identification and further development of management strategies.</p>

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Occurrence and Characterization of Exserohilum rostratum Causing Leaf Blight on Calathea ornata in India

  • 期刊论文

  • 发表日期：

    2025年11月26日

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  • Arghya Banerjee,
  • Shuvadeep Halder,
  • Saidul Islam,
  • Sunita Mahapatra,
  • Birendranath Panja

摘要

Calathea ornata (Syn. Goeppertia ornata) (family Marantaceae), native to South America, is an evergreen perennial ornamental house plant that has economic importance for beautiful pale green variegated leaves with pin-stripe. In July 2023, leaf blight of Calathea was observed in greenhouse of The Neotia University, West Bengal, India that cause 10 to 50% leaf area damage. Initial symptoms of the disease were small, brown spots that appeared on the upper surface of leaves, which gradually enlarged and coalesced. These necrotic lesions spread to cover the entire leaf surface and ultimately caused leaves to shrivel and die. Under stereo-binocular microscopy, mycelial fragments along with fungal structures was observed on dead leaf portion. The associated pathogen was isolated from the symptomatic leaves and pure culture was obtained on potato dextrose agar (PDA) media. Conidia observed on diseased tissue were multicelled with protruding hilum at the base, terminal cells thickened, olivaceous or brown, fusiform in shape with blunt tips, 5 to 11 septate and 6 to 11 septate on culture media, measuring average of 97 × 12 μm (n = 50) on diseased tissues and average of 96 × 11 μm (n = 50) on PDA, germinating by producing germ tubes semi axially from each end. DNA was extracted from mycelia of a representative fungal isolate (ER01) by following CTAB 2% method and two gene regions (ITS and GAPDH) were amplified and sequenced. Phylogenetic study revealed that our isolate closely related to Exserohilum rostratum. Additionally, pathogenicity test was conducted by conidial spray and disc inoculation method, which confirmed the pathogenic nature of E. rostratum on C. ornata. Based on cultural, morphological, molecular characteristics and pathogenicity test, the pathogen was identified to be E. rostratum. As the disease may lead to death of foliar part of the plant under adverse conditions, this study might be helpful in proper identification and further development of management strategies.