PJB-2020-150
Chemotherapeutic management of brown leaf spot of citrus caused by A. citri
Muhammad Shahzad
Abstract
Alternaria brown spot is very important disease of mandarins and its hybrids which is caused by Alternaria citri. This disease is most prevalent in humid subtropical citrus producing areas. Present study gives the new information about the selection of fungicides for this disease. Seven fungicides (Hexaconazole+ captan, mancozeb+ metalaxyl, difenoconazole, azoxystrobin+ flutriafol, freestyle aluminium and metiram) were evaluated against pathogen under in vitro conditions in Department of Plant Pathology, University of Agriculture Faisalabad. Three concentrations of each treatment as (250, 500, and 750) ppm were applied by poisoned food technique. Out of these fungicides difenoconazole completely inhibited mycelium of Alternaria alternata and expressed minimum growth (0.00) mm followed by hexaconazole+ captan, azoxystrobin+ flutriafol, thiophanate methyl, mancozeb+ metalaxyl, metiram and fosetyl aluminium (1.42, 1.93, 7.30, 7.52, 7.65, 7.67)mm in comparison to control dishes (15.22mm). Difenoconazole gave 100% results at all concentrations with 0.00 mm growth, also hexaconazole+ captan and azoxystrobin+ flutriafol at 500 ppm and 750 ppm inhibited the mycelium and expressed 0.00 mm growth. From the lab experiments top five chemicals (thiophanate methyl, difenoconazole, metiram, hexaconazole+ captan and azoxystrobin+ flutriafol) were selected and three concentrations (0.25, 0.50, 0.75) % of each treatment were sprayed on one-year old infected plants under RCBD. Similarly difenoconazole significantly reduced the disease incidence (23.0%), hexaconazole+ captan, and azoxystrobin+ flutriafol expressed disease incidence (29.70, 30.00)% respectively, thiophanate and metiram proved average by expressing disease incidence (38.90, 47.70)% respectively as compared to control (72)%. Difenoconazole is recommended to the growers of citrus for the management of ABS disease.
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