This study aimed to investigate the effect of eight Bacillus isolates and their culture filtrates on the linear growth and spore germination of Fusarium wilt pathogens (Fusarium oxysporum).
Studying the effect of eight Bacillus isolates on growth of Fusarium oxysporum showed that, Bacillus Subtilis No.2, Bacillus spp. No.2 and Bacillus Subtilis No.1 were the best antagonistic bacteria for limiting growth of F. oxysporum as they caused the highest inhibition zone (35.67, 34,00 and 30.33 mm) respectively. Bacillus spp. No.1 and Bacillus megtla (30.00 and 29.33 mm) came next whereas Bacillus spp No3 was the lowest effective one that caused the narrowest inhibition zone (25.33 mm).
Evaluating the effect of Bacillus culture filtrates at different concentrations on the linear growth and spore germination of Fusarium oxysporum revealed that, all filtrates of the tested Bacillus isolates reduced the mycelial growth and spore germination of F. oxysporum. All filtrates of the tested Bacillus isolates at 50% concentration completely inhabited spore germination of F. oxysporum. Culture filtrates of Bacillus Subtilis No.2 and Bacillus spp. No.2 also were more effective in reducing mycelial growth and reducing the growth of F. oxysporum by 73.00 and 72.59 % respectively. On the other hand Bacillus subtilis No.1 and Bacillus spp. No. 4 made lysis to mycelial of F. oxysporum. Generally linear growth and spore germination were decreased by increasing the concentrations of culture filtrates from 10% up to 50%.
Effect of treating cucumber seeds with Bacillus isolates on incidence of Fusarium wilt disease was studied under greenhouse conditions. Bacillus isolates were used singly as seed dressing.
Results revealed that all isolates were effective in reducing disease incidence and disease severity and increasing the percentage of healthy plants compared to the control. B. subtilis No. 2 and Bacillus spp. No. 2 were the best isolates in reducing disease incidence and disease severity while Bacillus spp. No. 6 was the least effective isolate. |
