ISOLATION AND IDENTIFICATION OF THE PATHOGEN CAUSING ROOT AND STEM ROT DISEASE ON COWPEA AND EVALUATION OF THE AZOTOBACTER VINELANDII EFFICACY FOR CONTROLLING THE DISEASE UNDER LABROTARY CONDETIONS | ||
| The Iraqi Journal of Agricultural Science | ||
| Article 1, Volume 43, Issue 0, February 2013, Pages 67-75 | ||
| Authors | ||
| M. A. Al-Mousawy; K. S. Jaber | ||
| Abstract | ||
| This research was carried out to isolate and identify the causal agent of root and stalk rot of cowpea in some governorate in central of Iraq,test the pathogenicity for the fungus and control it by using three isolates of the bacterium Azotobacter vinellandii. Results showed existance of Rhizoctonia solani in all samples at 15.75-35.00%. The fungus was identified as R. solani according to cultural and morphological characteristics. Pathogenic ability of R. solani by using cabbage seeds indicated that all the test isolate, were pathogenic, and showed different effects on cabbage seed germination. The percentage of seed germination in their treatments ranged between 0 to 54.66%, with the superiority of the two isolates, RS1 and RS4 which completely inhibited cabbage seed germination compared with control treatment which was 80%. The pathogenicity also showed that the isolates RS1, RS2, RS3 and RS4 were pathogenic to cowpea, they caused reduction in seed germination and increased in infection severity under glasshouse conditions. The percentage of seed germination and infection severity in their treatments ranged between 0 to 50% and 43.75 to 100% respectively compared with the 0.0 and 90% in the control treatment, with the superiority of RS1 which gave 100% infection severity and completely inhibited seed germination. Three pure isolates of A. vinelandii bacterium AV1, AV2 and AV3 caused significant reduction in the mean fungal growth of the two pathogenic isolates of R. solani (CRS1 and RS4) and increased percentage of inhibition. The mean of fungal growth and percentage of the inhibition in the treatments of bacterium isolates ranged 1.75-2.82 cm and 68.88-80.56% respectively compared with 9.00 cm and 0.00 % in the pathogenic fungal isolates without biocontrol agent. | ||
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