Effect of Selected Leaf Extracts on the Mycelial Radial Growth of Phytophthora sp. Causing Corm Rot of Colocasia (Colocasia esculenta L.)

In the present study the pathogenicity of Phytophthora sp. causing corm rot of colocasia was proved by Koch’s postulates. Sixteen infected corm samples were collected from different markets in two districts (West Godavari and East Godavari) of Andhra Pradesh and pot experiment was carried out in the Department of Plant Pathology, SHUATS, Prayagraj during Rabi season (2022-23). Out of those, the sample which collected from Kovvur Rythu Bazar, West Godavari district in Andhra Pradesh shows high pathogenicity. Five leaf extracts viz., neem, mint, lantana, tulsi and periwinkle @ 5, 10 and 15% concentrations were evaluated by using poisoned food technique against Phytophthora sp. Among all the leaf extracts, neem leaf extract @ 5, 10 and 15% concentrations recorded minimum radial growth (26.43, 24.73 and 22.77 mm, respectively) and maximum per cent inhibition (33.27, 37.59 and 42.55%, respectively) of Phytophthora sp. at 120 hrs of incubation as compared to other leaf extracts, treated (Metalaxyl) and untreated checks. The present study is limited to one trial in Prayagraj conditions, therefore to substantiate the present results more such trials are required in future for further recommendation.