The present work was carried out to study the effect of non–chemical methods as safe alternative to synthetic fungicides to control some soil borne fungal diseases of bean plants. Whereas, chemical pesticides might have injury on the environment and human health because it highly toxic substances produced in agricultural led to, great disturbance in biological balance.
Lab. studies showed that the most dangerous effects of Rhizoctonia solani and Sclerotium rolfsii have occurred at pre and post-emergence damping off of seedlings. All tested antagonists and their cultural filtrates at concentration 40%, at the age cultural of 10 and 3 days for antagonistic fungi and bacteria, respectively on pH 7 and temperature degree 20˚C caused significant reduction in the linear growth of both R. solani and S. rolfsii. The highest concentration (6.0%) of plant extracts caused a complete growth inhibition of the tested fungi. Trichoderma spp. as well as, bacterial isolates had the highest effect in reduction the mycelial growth of R. solani and S. rolfsii in medium contains low 2.5:1 C/N "Dextrose/Ammonium tartarte as the best sources of carbon and nitrogen" ratios. The two tested antagonists (T. harzianum and B. subtilis) caused malformation and changed color in the growing hyphae of both S. rolfsii and R. solani pathogens.
Greenhouse and field studies showed that all tested antagonist-treatments at the rate of 4g/kg seeds, plant extracts treatments at the concentration of 3% and compost as bean rich organic fertilizer at the rate of 12 kg/m2 have reduced the incidence of pre-emergence and post-emergence damping off and increased significantly the percentage of plant survivals in both seasons compared to the control. The antagonistic fungus T. harzianum when used as seed dressing at the rate of 4g/kg seeds was the most effective one in increasing the fresh and dry weight of shoots and roots, respectively. In addition increased the yield parameters "weight of pods/plant and dry weight of 100 seeds" during the two growing seasons 2008 and 2009, followed by T. viride, B. subtilis and P. fluorescens in comparison with control treatment. Garlic extract used as coating bean seeds at the concentration 3% was the most effective in increasing the yield parameters, followed by jojoba extract during the two growing seasons 2008 and 2009. On the other hand, marjoram extract was the less effective one in comparison with control. Compost, as bean rich organic fertilizer at the rate of 12 kg/m2 caused the highest increase in yield parameters during the two growing seasons. No clear significant differences were noticed between both plant residues and cow manure in respect to plant growth characteristics.
Key words: Bean, biocontrol agents, plant extracts, organic matters, damping off and root rot diseases.
Reference:-
Ahmed, M.F.A. (2013): Studies on non – chemical methods to control some soil borne fungal diseases of bean plants (Phaseolus vulgaris L.). Ph.D. Thesis. Faculty of Agriculture, Cairo Univ., pp. 156.