Evaluating The Efficacy of Azotobacter chroococcum Against The Pathogens of Okra Root Rot Disease in Babylon Province

Abstract

The field survey results revealed the spread of okra root rot disease in all surveyed areas. The results of isolation and diagnosis showed the presence of 6 fungal isolates associated with the roots of okra plants, differing in appearance in different regions. As Fusarium solani achieved the highest percentage of occurrence, it appeared in all samples with 80%, followed by Macrophomina phaseolina with an appearance of 44%, and Rhizoctonia solani recorded 21%. The results for pathogenicity showed that all tested fungi caused a significant reduction in the germination rate of radish seeds. The results indicated the effect of Fusarium. spp (FA3, FK2, FA1, FR1, FD2, FC1) and M.phaseolina (MB1, ME1) and R.solani (RR1) on germination of okra seeds. In infection of okra plants, the percentage of infection severity reached (88.3, 85)%, compared to the control treatment, which was 0%. The study showed that Azotobacter chroococcum has a high antagonistic capacity against the pathogenic fungi FA3 and ME1, and the inhibition rate varied according to the concentration or dilution used. The lath house results showed that A. chroococcum was controlled by the pathogen F.solani and M.phaseolina fungi. The severity of infection reached (31.66 and 28.33)%, respectively, compared to the treatment of pathogenic fungi alone, which amounted to (77.52 and 83.44%) respectively. The treatment of infection between bacteria and pathogenic fungi in the field experiment also achieved control in the severity of the disease and an increase in growth parameters measured, compared to the treatment of pathogenic fungi alone.