The severity and cause of leaf spot disease of Pongamia pinnata L. and fungicidal control of the pathogen

Abstract

A survey on the symptom and severity of the leaf spot disease of Pongamia pinnata L. was conducted in the nurseries of the Institute of Forestry and Environmental Sciences, University of Chittagong (IFESCU), Bangladesh Forest Research Institute (BFRI) and Aronnak Nursery in Chittagong. The highest infection percentage and disease index were found in IFESCU nursery, followed by BFRI and the lowest was recorded in Aronnak nursery. The associated organism of leaf spot disease of P. pinnata was isolated from the diseased plant parts and the pathogenicity was established with the isolated fungus. Colletorichum gloeosprioides Penz was proved to be pathogenic. The inhibition of mycelial growth of C. gloeosporioides was observed and identified as suitable fungicides (Bavistin, Cupravite and Dithane M-45) and doses (0.05, 0.10, 0.50, 1.00, 1.50 and 2.00). The lowest and highest mycelial growth were respectively found on Bavistin and on Cupravite at the concentration of 0.05 after 8th day of incubation. It indicates that out of the three tested fungicides, Bavistin showed most effective, followed by Diathane M-45, and Cupravite was ineffective for its very little inhibition on mycelial growth.