ETIOLOGY AND MANAGEMENT OF ANTHRACNOSE (Colletotrichum capsici) AND LEAF ROT (Phytophthora parasitica) IN BETELVINE
Loading...
Date
2019-11
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Horticultural Sciences, Bagalkot
Abstract
Anthracnose and leaf rot are the most severe and wide spread foliar diseases in betelvine growing areas of north Karnataka. Studies were carried out between 2016-2018 at Department of Plant Pathology, College of Horticulture, Bagalkote. Four districts were surveyed in which the Per cent Disease Index (PDI) ranged from 20.00 to 60.00 for both diseases. Haveri district recorded highest average anthracnose PDI (38.67) and least in Belagavi district (26.00). Maximum average leaf rot PDI (34.44) was noticed in Bagalkote district and least in Belagavi district (22.00). Causal agents of the diseases viz., anthracnose and leaf rot were confirmed as Colletotrichum capsici (C. capsici) and Phytophthora parasitica (P. parasitica) respectively through pathogenicity test, cultural, morphological and molecular identification.
Growth of C. capsici tested on nine different media, among them PDA showed maximum mycelial growth (8.72 cm) followed by oat meal agar (8.53 cm) and minimum growth was recorded on V-8 juice agar (4.25 cm) eight days after incubation. Effect of different temperature and pH on the growth of C. capsici were tested and results revealed that temperature of 30 oC (450.75 mg) and pH 5.0 (356.21 mg) were found optimum.
Similarly in case of P. parasitica, maximum growth was observed in Czapek‟s dox agar (8.70 cm), followed by Sabouraud‟s agar (8.53 cm) and minimum growth was recorded on malt extract agar (4.20 cm) eight days of incubation. Among tested different temperature and pH, temperature of temperature 20 oC (338.15 mg) and pH 8.0 (360.88 mg) were found optimum.
Fungicides evaluated under in vitro against C. capsici revealed that COC, carbendazim + mancozeb, captan + hexaconazole and tricyclazole + mancozeb and mancozeb at 1000 ppm and carbendazim and tebuconazole at 250, 500 and 1000 ppm completely inhibited the growth. While, in case of P. parasitica, all contact and combiproducts tested at 2000 ppm and tebuconazole tested at 1000 ppm completely inhibited the growth.
Under field condition application of two sprays of carbendazim (12 %)+ mancozeb (63 %) found effective against anthracnose with least PDI (23.21) and Metalaxyl (4 %) + Mancozeb (64 %) found effective against leaf rot with least PDI (26.41). Residue analysis revealed that even at 5 days after spray, residue level of Metalaxyl (0.601 mg/kg) and mancozeb (0.291 mg/kg) were below the MRL values. Whereas, in case of carbendazim + mancozeb residue values of mancozeb (0.014 mg/kg) was less than the MRL values even at 5 days after spray, but residue value of carbendazim (0.652 mg/kg) was found more than MRL value at 30 days after spray.