Studies on the management of alternaria alternata causing leaf spot of okra
Loading...
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
JNKVV, Jabalpur
Abstract
Okra is an important vegetable crop with a diverse array of nutritional quality and potential health benefits. India ranks first in area and production of okra. The crop occupies nearly 511 thousand hectares area, production 5848.6 thousand metric tones and productivity of 11.40 metric tones/ha. In Madhya pradesh okra crop occupies area 27.11 thousand hectares with production 342.05 thousand metric tonnes and productivity 12.62 metric tones/ha. The present investigation, “Studies on the management of Alternaria alternata causing leaf spot of okra” was mainly focused on isolation, purification, cultural studies, pathogenicity, effect ofvarious doses of Nitrogen and carbon sources, management through plant extract,oil cakes, chemicals andImpact of different levels depth of burial on survival of Alternaria alternata. Pathogenicity test was performed by by artificial inoculation with spore suspension (1 x 103 spores / ml) on leaves of okra. Four different nitrogen sources viz., Sodium nitrate, Potassium nitrate, Urea and Peptone in Richards' agar medium were tested to know their effect on the growth of A. alternata. Potassium nitrate found better growth of A. alternata followed by Peptone Sodium nitrate. Poor mycelial growth was recorded in Urea. Five different carbon sources viz., Dextrose, Mannitol, Sucrose, Fructose and Galactose were tested in Richards' agar medium to know their effect on the growth by fungus.sucrose found better growth of A. alternata followed by Fructose, Dextrose, galactose, manitol are least effective against the target pathogen. A set of nine phyto-extracts including Neem, Tulsi, Karanj, Jatropha, Babul, Ashok, Bauganivillea, mendhi and Neelgiri were used to evaluate their efficacy in inhibiting A. alternata at 10, 20 and 30 per cent concentrations under in vitro conditions using poisoned food technique. Neem leaf extract was found very promising in inhibiting the growth of test pathogen as it produced 50.75 percent growth inhibition of A. alternata. A set of four Oil cake including Neem cake, Linseed cake Cotton cake and Mustard cake were used to evaluate their efficacy in inhibiting A. alternata at 10, 20 and 30 per cent concentrations under in vitro conditions using poisoned food technique. Mustard cake was found very promising in inhibiting the growth of test pathogen as it produced 54.23 percent growth inhibition of A. alternata at 30 percent concentration. A set of nine fungicides namely Tebuconazole, Hexaconazole, Mencozeb, Copper oxychloride, Carbandazim, Thiram, Propiconazole, Copper oxychloride + Carbandazim and captan + Hexaconazole were tested for their efficacy againsA. alternata under in vitro condition using Poisoned food technique at four different concentration of respective fungicide (10 ppm, 25 ppm, 50 ppm, 100 ppm).Propiconazol found best fungicides for inhibition of radial growth of A. alternata. The pathogen A. alternata survived for 90 days in infected plant debris in pot soil. Duration of survival is reduced as depth of burial increased and maximum growth found at 2.5 cm depth after 120 hours of incubation period.