Curvularia eragrostidis, a new threat to large cardamom (Amomum subulatum Roxb.) causing leaf blight in Sikkim

Abstract

Large cardamom (Amomum subulatum Roxb.) is now affected by several diseases caused by both viruses and fungi. At present, leaf blight is considered a major threat to cardamom cultivation in Sikkim. During the past two decades, cultivation of the crop in this region has dropped by almost 60%. Hence, to quantify the severity of leaf blight damage and identification of the causal organism for the disease, a survey was conducted from May to August 2017 in different large cardamom growing regions of Sikkim. During this survey, a typical symptom of leaf blight was observed on cardamom leaves in many locations. The leaves with blights were collected, surface sterilized, and inoculated on potato dextrose agar (PDA). The pathogen was isolated as pure culture, and on the basis of morphological and microscopic characteristics, the fungus was identified species of Curvularia. Molecular characterization of the fungal isolate with ITS-rDNA partial gene amplification using universal primers (ITS4 and ITS5), showed 100% similarity with Curvularia eragrostidis (family: Pleosporaceae). The fungal isolate and nucleotide sequence was deposited in National Fungal Culture Collection of India (NFCCI), Pune and NCBI with accession numbers NFCCI 4541 and MN710527, respectively. This is the first report on the occurrence of C. eragrostidis pathogen causing leaf blight of large cardamom grown in Sikkim.