PATHOGENICITY AND CHEMICAL CONTROL OF BASAL ROT OF ONION CAUSED BY FUSARIUM OXYSPORUM F. SP. CEPAE
Keywords:Allium cepa, basal rot, fungicides, Fusarium oxysporum, inoculation methods
Many Fusarium spp. have been reported to be associated with onion diseases and cause economically significant losses wherever onion is grown. F. oxysporum f. sp. cepae was isolated from diseased bulbs. Pathogenicity of isolated specie was confirmed with two methods of inoculation (seedling infestation method and soil infestation method). Both methods of inoculation showed substantial impact on disease development and plant growth. Seedling infestation method caused maximum reduction in plant germination, followed by soil infestation method as compared to control. Highest plant mortality as well as pathogen infection was recorded in soil infestation method, followed by seedling infestation method as compared to control. Four fungicides i.e. Antracol, Carbendazim, Copper oxychloride and Kingmil MZ with 10, 100, 1000 and 10000 ppm concentrations were evaluated against F. oxysporum under in-vitro as well as in-vivo conditions. A positive correlation was observed between concentrations of fungicides used and resulting inhibition of fungal growth. Among four fungicides, Carbendazim, followed by Antracol appeared as the most effective fungicides. Application of fungicides brought a remarkable increase in seedling emergence of treated plants inoculated with F. oxysporum as compared to the untreated plants. The most effective fungicide treatments, which produced highest seedling emergence (100%), were 10000 ppm of Antracol, Carbendazim and Copper oxychloride. Infection percentage and plant mortality decreased and minimum were recorded after the application of 10000 ppm of Antracol, Carbendazim, Copper oxychloride, Kingmil MZ and 1000 ppm of Carbendazim. Significant differences were also observed between plant growth (shoot length and weight, root length and weight) of treated and untreated (control) plants inoculated with F. oxysporum. Maximum plant growth was recorded in case of 10000 ppm of Carbendazim followed by Antracol 10000 ppm and Copper oxychloride. Whereas, minimum plant growth was observed in untreated plants inoculated with F. oxysporum, followed by Kingmil MZ 10 ppm and Copper oxychloride 10 ppm.
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