Leaf spot management of Pongamia pinnata seedlings by Cleistanthus collinus plant extracts

Abstract

The in vitro and in vivo antifungal potency of Methanol extract of leaf and bark of Cleistanthus collinus plant were evaluated for their botanical fungitoxicants on Colletorichum gloeosprioides Penz. causing leaf spot in Pongamia pinnata seedlings. Different concentrations of extract (0.25, 0.5, 1 and 2%) of leaf and bark and one fungicide (Indofil-M 45) were appraised against the pathogen in vitro using the ‘poison food technique’. The fungitoxicity was better with leaf than bark extracts. Treatment with 2% leaf extract resulted in complete inhibition of mycelial growth; whereas in 2% bark extract fungal growth inhibition was only 93%. The result of other concentrations was between 80-45%. The percentage of inhibition was directly proportional to the concentration. In vivo studies, seedlings were treated with 3 concentrations (0.25, 0.5 and1%) of leaf and bark extract by two sequential foliar sprays at an interval of 15 days. Reduction in disease severity was not significant in the first month after treatment. But in second month onwards, significant decrease in percentage of infection and their severity (DSI) was observed. Leaf extract of 0.5% and bark extract of 1% was on par with chemical fungicide (Indofil-M45) and 1% leaf extract was better in controlling disease incidence. The effectiveness of this botanical fungicide was similar to that of chemical fungicide. Thus, the present study recommends the use of C. collinus leaf extract at a minimal concentration of 1% for maximum inhibition of leaf spot disease in seedlings.