The sesame charcoal rot disease (Macrophomina phaseolina Tassi (Goid)) was successfully controlled under greenhouse conditions by using several practices. Treating sesame seeds with Trichoderma harzianum produced the highest percentages of healthy mature plants (96.7%) followed by Chaetomium bostrycoides (90.0%), Trichoderma sp 5 (83.3%) and T. hamatum (80.0%). Moreover, soaking seeds in the filtered extracts of thyme, rhubarb or garlic or autoclaved extracts of cumin or azedrach maximized the healthy mature plants (83.3-86.7%). While, soaking seeds in Indole butyric acid (IBA) at 100 ppm or SA at 4 mM produced 100.0% and 96.7% healthy standing plants, respectively. The probable biochemical defense mechanisms that induced by these treatments in term of oxidative enzymes, phenol and sugars content were investigated and discussed.
Applying soil preparations of the VAM (vesicular arbuscular mycorrhiza) fungi showed no significant effect on the post-emergence and charcoal rot incidence. The soil preparation containing different Glomus spp. (G1+G2+G3+G4) produced the highest % healthy standing plants (86.7%) followed by G1 alone (76.7%), G3+G4 (70.0%), G2+G3 (63.3%), and G4 (63.3%) compared with control (36.7%). In another experiment, mixture of 4 VAM fungi grown in vitro on autoclaved barely-sand modified medium was used at different rates. Applying this mixture at rates of 2g/Kg soil produced the highest significant increase in healthy standing plants (70.0%) compared with control (30.0%). The incidence of charcoal rot was decreased significantly only at rates 1 and 2 g/Kg soil (2.5-7.5%) compared with control treatment (22.5%).
Key words: Sesame, charcoal rot, Macrophomina phaseolina, antagonistic microorganisms, plant extracts, resistant inducing agents, axenic culture, vesicular arbuscular mycorrhiza, VAM fungi.
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