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 tire 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 tire effect of some resistance
inducing agents i.e., 7 chemical inducers on disease incidence.
Tire most effective agents and concentrations for controlling pre-emergence
damping-off in soil infested witlrM phaseolina were salicylic acid & bion at 4 mM,
tanic acid at 8 mM, IBA at 400 ppm and H2C2 & 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 inM. 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 treatments were H2O2 at 0.5% and Tanic acid 1 mM. |
