الفهرس | Only 14 pages are availabe for public view |
Abstract The causal organism of early blight disease and chocolate spot disease were isolated from diseased samples of tomato and faba bean plants, respectively during the growing season 2017/2018. Samples were collected from tomato fields in Giza Govemorate and from faba bean fields in Menoufia Govemorate. 32 actinobacteria isolates were isolated from the rhizosphere of tomato and faba bean plants. Streptomyces nodosus was the most efficient in reducing the mycelial growth and sporulation of Alternaria solani and Botrytis fabae, respectively. Biomass production of S. nodosus as well as antagonistic activity were optimized. The optimized medium was of the following composition (g/100ml): 2 (gm) starch, 0.2 (gm) of potassium nitrate, dipotassium hydrogen phosphate as .” . phosphorus source at 30°C and pH 6.5, that lead to the more production of biomass and antagonistic substance(s). Cultures were incubated in a shaking incubator at 180 rpm. Streptomyces nodosus was significantly decreased the severity of early blight and chocolate spot disease under greenhouse conditions in compared to the control. Also, seeds of tomato and faba bean coated with S. nodosus showed a reduction in severity of early blight and chocolate spot disease under greenhouse conditions in compared with control. The active antimicrobial compound has been identified as amphotericin B. Separation, purification and identification were carried out using physical and chemical characters. Extracted amphotericin B has high potential effective as a biocontrol agent against A. solani and B. fabae. The results revealed that spraying tomato and faba bean plants with amphotericin B was significantly decreased the severity of early blight disease and chocolate spot disease in compared to the control under greenhouse conditions. Tests showed that clove oil was the best effective oil in the control of the mycelial growth of A. solani and B. fabae. Also, the combination of clove oil with extracted amphotericin B was more effective in disease control. Additionally, Results showed that Dithane M-45 was the effective fungicides in controlling the mycelial growth of A. solani and B. fabae. Also, the combination of Dithane M-45 with extracted amphotericin B was more effective in disease control. |