Macrophomina phaseolina and Fusarium oxysporum were isolated from sesame seeds by using Agar plate and blotter methods. Pathogenicity test using sesame seeds cv Giza 32 illustrated that M. phaseolina and F. oxysporum are the causal agents of charcoal rot and wilt diseases. Laboratory experiments were carried out to study the effect of 7 chemical inducers on the linear growth (LG) of M. phaseolina and F. oxysporum. Studying the effect of different concentrations of some inducing resistance agents on the linear growth (mm) of 4 isolates representing each fungus showed that the linear growth of the tested isolates was significantly suppressed by all chemical inducers i.e., Potassium Chloride, Hydrogen Peroxide, Acetic Acid, Butyric Acid, Tanic Acid, Salicylic Acid and Bion, respectively. Greenhouse experiments were carried out to study the effect of some resistance inducing agents i.e., 7 chemical inducers on disease incidence. The most effective agents and concentrations for controlling pre-emergence damping-off in soil infested with M. phaseolina were salicylic acid & Bion at 4 mM, tanic acid at 8 mM, IBA at 400 ppm and H2O2 & KC1 at 4%, respectively. The effect of the chemical inducing agents on controlling wilt disease caused by F. oxysporum indicated that IAA and SA were the most effective inducers for decreasing pre-emergence damping-off, respectively, followed by Bion, IBA KC1 and H2O2. However, the most effective concentrations for controlling pre-emergence damping-off were IAA at 400 ppm and SA at 8 mM. The highest increase in survived plants was recorded at IAA at 400 ppm and SA at 8 mM, respectively compared to control treatment The least effective reatments were H2O2 at 0.5% and Tanic acid 1 mM. |
