Botrytris cinerea, Sclerotinia sclerotiorum and Pythium aphendermatum were highly pathogenic on un-wounded and wounded snap bean pods of cv. Paulista under pathogenicity test. The in vitro and in vivo results indicated that all tested plant oils reduced the growth and
they were effective in reducing the infection and disease severity percentages on detached pods inoculated individually with the three mold pathogens. Eugenol oil was the best one among all tested plant oils where all its tested concentrations inhibited the growth of all tested pathogens
and prevented completely the infection on bean pods with any one of the tested pathogens. S. sclerotiorum was the most sensitive among all tested pathogens to all tested plant oils with their concentrations, while B. cinerea was the least sensitive one followed by P. aphendermatum. Also,
increasing the concentration of tested plant oils from 0.1-5.0% increased gradually the effect of oils in reducing the growth of tested pathogens. On the other hand, the other tested plant oils differed in their effect in reducing the infection and disease severity % on inoculated pods with the tested pathogens. In this respect, thymol was effective in controlling the infection and disease severity on inoculated pods with B. cinerea. Meanwhile, thymol was less effective in controlling the infection with P. aphendermatum and S. sclerotiorum. Also, anisol, fennchone and camphore oils were moderately effective in controlling the infection of bean pods with B. cinerea and P. aphendermatum. Also, it was clear that all tested plant oils were effective in controlling bean pod mold infection under greenhouse conditions. Concerning the activities of peroxidase and polyphenoloxidase in inoculated and un-inoculated bean pods of cv. Paulista, the activities of both enzymes were increased in inoculated and un-inoculated bean pods with the tested mold pathogens. Also, the activities of peroxidase and polyphenoloxidase correlated with increasing
the incubation periods from 4-13 days. Additionally, treating the inoculated and non-inoculated bean pods with some plant oils encouraged the increase in activities of peroxidase and
polyphenoloxidase enzymes. In this respect, the highest activities of peroxidase were recorded With eugenol oil treatment of inoculated bean pods with the three tested mold pathogens. |
