Prof. Abdou Mahdy Mohamed Mahdy :: Publications:

This study aimed to investigate the effect of four pseudomonas & two serratia isolates and their culture filtrates on the linear growth and spore germination of Fusarium wilt pathogens (Fusarium oxysporum). Studying the effect of four pseudomonas and two serratia isolates on growth of Fusarium oxysporum showed that, pseudomonas fluorescens No.2, pseudomonas fluorescens No.3 and serratia marcensens No.2 were the best antagonistic bacteria for limiting growth of F. oxysporum they caused the highest inhibition zone (37.33, 35,00 and 31.33 mm) respectively. Pseudomonas fluorescens No.1 (30.67 mm) came next whereas pseudomonas putida was the lowest effective one that caused the narrowest inhibition zone (27.33 mm). Evaluating the effect of pseudomonas and serratia culture filtrates at three concentrations (10, 25, 50%) on the linear growth and spore germination of Fusarium oxysporum revealed that, all filtrates of the tested isolates reduced the mycelial growth and spore germination of F. oxysporum. All filtrates of the tested isolates at 50% concentration completely inhabited spore germination of F. oxysporum. Culture filtrates of pseudomonas putida and serratia marcensens No.2 at 50% concentration were more effective and reducing the mycelial growth of F. oxysporum by 80.74 and 80.37 % respectively. In this respect all tested isolates made lysis to mycelial of F. oxysporum except pseudomonas fluorescens. No.3. 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 cell suspension of pseudomonas and serratia isolates on incidence of Fusarium wilt disease was studied under greenhouse conditions. All 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. Pseudomonas fluorescens No.3 and serratia marcensens No.2 were the best isolates and completely prevented the disease incidence. Serratia marcensens No.1came next and reducing disease incidence and disease severity by (83.33 and 97.33%) respectively while pseudomonas putida. No. 6 was the least effective isolate.