Target Leaf-spot Disease of Rauvolfia serpentina and its Chemical Control

At the Institute campus, plantations of Rauvolfia serpentina (Linn.) Benth. ex Kurz, a herbaceous crop of medicinal importance, suffered heavily from a leaf spot disease, caused by Corynespora cassiicola (Berk. & Curt.) Wei, whose pathogenicity was proved by inoculation experiments. Following initial screening of fungicides, fixing the dosage to be used and time of application as to whether they should be applied as prophylactic or curative, field trials were conducted using chemicals at 0.25% solution in water as prophylactic sprays applied six times at monthly intervals from June to November. Of the 4 fungicides tested in the field, only Captan proved effective in controlling the leaf spot disease resulting in significant increase in ischolar_main yield. The net increase in ischolar_main yield per acre in terms of money value was found to be about Rs. 85, Rs. 601 and Rs. 2,222 at the end of first, second and third year respectively.