Reduction in fungicide usage by monitored control of apple scab (Venturia inaequalis (Cke.) Wint.).

摘要

An experiment was conducted during the 1991 and 1992 spring seasons to study the protective, post-infection and post-symptom activity of fungicides against apple scab (V. inaequalis) in apple growing areas in Kotkhai, Himachal Pradesh, India. Mancozeb (0.3%), chlorothalonil (0.2%), dodine (0.075%), carbendazim (0.05%) and the sterol-inhibiting fungicides, bitertanol (0.075%), hexaconazole (0.03%), penconazole (0.05%) and myclobutanil (0.04%) were effective in controlling the disease when used as protective sprays throughout the apple growing season. The sterol-inhibiting fungicides, bitertanol (0.075%), penconazole (0.05%), fenarimol (0.04%), hexaconazole (0.03%), cyproconazole (0.02%) and flusilazole (0.01%) were also effective when sprayed 120 hafter the infection had started. Dodine (0.075%) showed a 72 h kick-back action which was only 24 h in carbendazim (0.05%). Sterol-inhibiting fungicides and dodine were also effective when they were applied on established scab lesions on apple foliage.They inhibited the production of secondary inoculum. The eradicative spray programme was almost as effective as the protective and curative, but the former was the most economic with 4 applications.