Evaluation of fungicides against foot and stem rot and Phoma leaf spot of roselle and their impact on fibre yield

Abstract

Foot and stem rot (FSR) and Phoma leaf spot caused by Phytophthora parasitica var. sabdariffae and Phoma sabdariffae are the two major diseases, affecting the roselle cultivation across India and worldwide. The efficacy of different group of fungicides like, Acetamida-Dithiocarbamate, Methoxyacrylates, Trifloxystrobin and Tebuconazole, Phenyl amide and Copper compound were assessed under field conditions against FSR and Phoma leaf spot. Duncan’s multiple range test (DMRT) was used to determine significant difference (p < 0.05) between the treatments. Seed treatment with cymoxanil 8% + mancozeb 64% WP @ 3 g kg−1 seed + prophylactic foliar spraying of cymoxanil 8% + mancozeb 64% WP @ 0.3% at 30 and 45 days of crop age showed lowest disease incidence (3.66 and 2.93%) against FSR and Phoma leaf spot disease as compared to the untreated control (9.73 and 7.66%) and exhibited higher plant height (350 cm), high basal diameter (17.51 cm), highest benefit–cost ratio (2.1), more incremental benefit–cost ratio (15.6) and highest fibre yield (26.53 q/ha) over untreated control.