Biological control and pathogenicity of the Fusarium oxysporum caused onion wilt in different localities of sindh and baltistan region

Abstract

In arrange to verify the pathogenic character of isolated fungus F. oxysporum the (f.sp Cepa) the pathogenicity test was conductod on commonly growing onion varioty Hazari by root and shoot infestation method. In general these methods of inoculation showed substantial impact on disease development and plant growth. Onion germinalion was significanty reduced in pots either inoculated by shoot or root infestation method as compared to the un-inoculated plants (control). However, root infestation method caused maximum reduction in plant germmation (60%) followod by shoot infestation method (39% as comparod to control). Similar trend were also observd in plant mortality, where highest plant mortality were recorded in root infestation method as compared to control (28%). Significant differences were also observed between plant growth in inoculated and un- inoculated plants. The plant growth parameters were also significantly varied with method of inoculation. Minimum root length were recorded in shoot infestation method (5.34 cm) as compared to control (10.74 cm).Similarly minimum root weight were recordod in root infestation method (1776 mg) followed by shoot infestation method (1296 mg) as compared to control (0,22 mg). Reisolation of the inoculated fungus was confirmed as of pathogenic nature F. oxysporum was re-isolated significantly in higher frequency in root infestation method (84.78%) as compared to shoot infestation method also showed some infection of F. oxysporum (10%). It could be either due to the soil-bome nature of the F oxysporum or as a result of secondary infection from inoculated plants. During the studies regarding the management it was found that the disease can be managed significantly through certain management strategies like by the use of Trichoderma verdii.