POSTHARVEST DISEASES OF SOME SELECTED SPICES, THEIR CAUSES AND MANAGEMENT

Abstract

A study was conducted to observe the prevalence of postharvest diseases of some selected spices (onion, garlic, ginger and chilli) and to identify their causes in storage. The experiment was conducted in the MS Laboratory of Department of Plant Pathology, Faculty of Agriculture, Sher-e-Bangla Agricultural University during the period of March, 2019- March, 2020. Spice samples were collected from five noted whole sale markets of Dhaka and from farmers field of Faridpur district. During each visit one (1) kg of samples of each spice was collected randomly from each of the market places. Sample collection was carried out thrice. Diseased spice samples were sorted out. The most frequent diseases found in the collected samples were black mould, blue mould, soft rot, Fusarium dry rot, anthracnose etc. Pathogens were isolated by tissue planting method and dilution plate method for fungi and bacteria, respectively. Several biochemical tests like Gram’s staining, KOH solubility, starch hydrolysis, oxidase, catalase, motility, casein hydrolysate, citrate utilization, lactose, sucrose, dextrose tests were conducted to identify the bacteria isolated from collected samples. This study revealed that collected samples were infected by Fusarium oxysporum causing Fusarium dry rot of ginger and chilli (3.97%), Aspergillus niger causing black mould of onion and garlic (8%), Aspergillus flavus causing green mould of onion (2%), Penicillium sp causing blue mould of onion (5.90%), Colletotrichum capsici causing anthracnose of chilli (3.5%), Bacillus subtilis causing soft rot of onion (3.68%), Pseudomonas aeruginosa causing soft rot of garlic (5%), Pseudomonas geniculata causing soft rot of ginger (3%), Serratia marcesens causing soft rot of garlic (3%). Identification of the bacteria was confirmed by extracting DNA from the bacterial cultures. The DNA samples were subjected to PCR using primer 27F: AGA GTT TGA TCM TGG CTC AG and primer 1492 R: CGG TTA CCT TGT TAC GAC TT, which produced around 1465-bp amplicons that were purified and sequenced using the same primers. DNA sequences of D1/D2 domain of 16s rDNA sequences of isolated bacteria were submitted to National Center for Biotechnology Information (NCBI) for deposition in the GenBank and obtain accession number. The obtained accession no. MW404211 for Pseudomonas aeruginosa strain SAU-2, accession no. MW404212 for Pseudomonas geniculata strain SAU-3, accession no. MW404213 for Serratia marcescens strain SAU-4. However, further research needed to conduct to observe the diversity of the postharvest diseases of spices for the potential control of postharvest diseases of spices. Spices can store in paper bag up to 30 days at average 29