چكيده لاتين :
CONTROL OF SEED-BORNE BEAN PATHOGENS WITH SOME ANTAGONISTIC FUNGI AND NON FUNGICIDAL TREATMENTS.ABSTRACT
Ten associated fungi of bean seeds were isolated, purified and identified as
Alternaria alternata, Aspergillus spp., Botrytis cinerea, Fusarium solani,
Macrophomina phaseolina, Penicillium sp., Rhizoctonia solani, Sclerotinia
sclerotiorum, Trichoderma viride and Verticillium spp. Four tested fungal isolates (R.
solani, M. phaseolina, F. solani, and S. sclerotiorum) were proved to be pathogenic
producing different degrees of pre-emergence and post-emergence damping-off and
root rot symptoms on bean cultivars, namely; Contender, Narina, Bolista and Giza-6.
The most virulent isolates inducing PRD were F. solani, M. phaseolina and R. solani
whereas S. sclerotiorum was the least virulent. Moreover, the highest levels of PTD
were obtained with S. sclerotiorum, F. solani, and R. solani, whereas M. phaseolina
was the least virulent. Bolista cultivar was the most compatible with PRD and PTD in
all tested pathogenic fungi, whereas Giza-6 showed the lowest compatibility. The
highest percentage of root rot infection were obtained in Bolista cultivar in tested fungi
ranged from (70-80%) and Narina (70-75%), while the least infection was obtained in
Giza-6 (55-60%). Plant oils (Cinnamon, Clove, Spearmint and Lemon) were in vitro
tested for their antifungal activity against the four tested pathogenic fungi. They
significantly reduced the radial growth was obtaining. Spearmint oil exhibited the
highest antagonistic effect to the tested fungi followed by Clove and Cinnamon oils,
while the least effect was Lemon oil as compared with control. Hyphal growth of R.
solani and S. sclerotiorum was completely inhibited by 100% and 75% conc. of
Spearmint oil, while R. solani was completely inhibited by 100% conc. of Cinnamon
oil. Also, the biological agents Trichoderma viride, T. harzianum, T. koningii and
Bacillus subtilis were used in vitro to evaluate their effectiveness against the four
tested pathogenic fungi. Linear growth experiments showed that all biological agents
were significantly reduced the linear growth of fungi. T. harzianum showed highly
antagonistic effect, the growth reduction ranged from (75.6 to 77.8%), while B. subtilis
was the least, growth reduction ranged from (56.7 to 65.6%) to the four tested
pathogenic fungi.
Keywords: Antagonistic fungi, Biological agents, Bean seeds, Damping-off
pathogens, Plant oils, Bacillus subtilis, Root-rot pathogens,
Trichodermat spp.
