EFFICACY OF CHEMICAL AND BIOLOGICAL TREATMENTS FOR CONTROLLING SOIL-BORNE PATHOGENS OF SOYBEAN
2009
Ahmed Awad Altalb
Several soil-borne fungal pathogens attack soybean plants, causing seedling damping-off and root rot diseases, in Egypt. Isolation trials from rooted rots of soybean, collected from various locations at Gharbiya, Kafr El-Sheikh and Minufiya governorates, revealed that Rhizoctonia solani, Fusarium solani and Macrophomina phaseolina were the most virulent and predominant pathogens. All the tested fungicides significantly reduced linear growth of the tested pathogens. Three known bioagents i.e. Trichoderma harzianum, T. hamatum and Bacillus subtilis were tested against such pathogens, and revealed remarkable effect in reducing mycelial growth on PDA medium. T. hamatum, mainly, grew over the mycelium of the tested pathogens. Under greenhouse conditions, both the fungicides and antagonists gave significant reductions of root rot severity, but fungicides were more effective than biocontrol agents in reducing the disease. Application of the selective antagonists and fungicides significantly decreased soybean root rot than untreated check, in naturally pathogen- infested fields. Plant growth and activity of nitrogenase enzyme were enhanced greatly, when the fungicides were applied compared with antagonists treatments.
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