GROWTH AND SPORULATION OF Magnaporthe oryzae CAUSING BLAST OF RICE IN SELECTED CULTURE MEDIA AND ITS In vitro MANAGEMENT

Abstract

An experiment was carried out at Molecular Biology and Plant Virology Laboratory, under the Department of Plant Pathology, Sher-e-Bangla Agricultural University, Dhaka-1207. The study was designed to aid in further experiments and find out the suitable measures to control rice blast pathogen. The study consisted of the isolation of rice blast pathogen from the field sample for morphological study, the evaluation of 12 different selected solid media to have a comparative analysis of their performance on morphological study of Magnaporthe oryzae, the pathogenicity test through Koch’s postulates and evaluation of efficacy of four latest chemicals against Magnaporthe oryzae. Diseased samples were collected randomly from the severely rice blast infected field from Mymensingh and Thakurgaon districts. The disease affected plant parts were collected and conveyed to the laboratory for in-vitro experiments. The morphological study was done by observing two isolates from the collected samples. It is evident that the disease was caused by Magnaporthe oryzae as the isolates produced pyriform, 3 celled hyaline conidia which had two septa. Among the 12 selected media PDA, CDA and PSA gave better performance in terms of mycelial growth and PSA, PR S DA for sporulation. On the other hand, PA (Prune agar) and SA (Starch agar) also gave good performance and these media can be a good alternative for morphological study and isolation purpose. Among the four selected fungicides, Amister top 325 SC and Blastin 75 WDG gave 100% mycelial growth inhibition with 500 ppm, 1000 ppm and 1500 ppm doses against Magnaporthe oryzae invitro. Besides, Acibean 28 SC and Deconil 500 SC had lower effect on rice blast pathogen

over control.