Leaf Blight Caused by Colletotrichum Fructicola of Large Cardamom (Amomum Subulatam Roxb.) an Important Cash Crop Grown in Sikkim, India

Large cardamom (Amommum subulatum Roxb.) a high valued spice crop grown in Sikkim Himalaya is now facing a devastating leaf blight disease that has brought down the yield drastically. Present study was focused on identification of this major fungal pathogen based on the morphological and molecular characterization. During this study infected leaves of large cardamom with blighted appearance were collected from all the four districts of Sikkim. The pathogen was isolated using Potato Dextrose Agar (PDA) medium, incubated at 25°C. The mycelium was septate, hyaline, and 2-4 µm wide. The conidiospores were cylindrical with both ends rounded, sometimes oblong. Length and breadth were 11-12 µm and 3-4 µm, respectively. On the basis colony morphology, growth and microscopic observations, out of the total 48 samples studied Colletotrichum sp. was identified from 14 samples. Based on phylogenetic analysis of the ITS4, ITS5 and ApMAT genes and phenotypic characters (colony morphology, microscopic features) the isolate (No. LC05) isolated from the sample collected from the village Assam Linzey, East Sikkim showed 100% homology with Colletotrichum fructicola from NCBI database. The pathogenicity of C. fructicola was also confirmed during the study. The fungal culture has been deposited at the NFCCI-ARI, Pune with an accession number NFCCI 4542 and the sequences have been deposited in NCBI GenBank with accession number (ITS) MN710587, (ApMAT) MW348934 respectively. To the best of our knowledge this is the first report of C. fructicola causing blight disease of large cardamom. Also the finding is very important to improve the disease control strategies of this high valued cash crop.