investigation of the reaction of olive cultivars to defoliate and non-defoliate isolates of verticillium dahliae kleb. in golestan province

abstract verticillium wilt of olive caused by verticillium dahliae is one of the main constraints to olive production in golestan province. in this research, two defoliating and two non-defoliating isolates of the fungus were inoculated in 16-18 months-old olive seedlings. the seedlings consisted of concervolia, cronaiki, kalamon, zard-roghani, bladi, mission, manzanilla and sevillana. the seedlings were inoculated using root dip assay. the seedling’s root tips were submerged in (4×106 spore/ml) spore suspension. the experimental design was conducted as factorial in complete randomized design, with three replicates. all inoculated seedlings were incubated under greenhouse conditions at 25-35˚c for 11 weeks. disease severity was evaluated using 0-5 scale. mean of disease severity was significantly different (p%1) in different cultivars by lsd test. cronaiki and calamon were less sensitive and the mean disease severities were 1.71 & 1.85, respectively. while, mission, conservolia, zard-roghani and bladi were severely sensitive and the mean of their disease severities were 3.85, 3.8, 3.75 and 3.33, respectively. mozanilla and sevillana were partially sensitive, and the mean of their disease severities were 3 and 2.61, respectively.