EFFECT OF SOME INDUCING FACTORS IN CONTROLLING POTATO ROOT ROT DISEASE CAUSED BY FUNGUS RHIZOCTONIA SOLANI

Results of isolation and phenotypic and molecular diagnosis showed that fungus Rhizoctonia solani is the main cause of potato root rot disease, while tests results of antagonistic ability of three isolates of fungus Trichoderma harzianum (University of Anbar - College of Agriculture - Department of Plant Protection - Plant Diseases Laboratory) against fungus R.solani on the medium recorded highest percentage of inhibition was achieved by agricultural PDA, where degree of antagonism was 1 according to Bell scale (4), while Pseudomonas fluorescens (University of Anbar - College of Agriculture - Department of Soil and Water Resources - Microbiology Laboratory) achieved highest percentage of inhibition 70%, while no types of bacteria Pseudomonas Mendacina (University of Anbar - College of Agriculture - Plant Protection Department - Plant Diseases Laboratory) achieved any inhibition rate against fungus R.solani, as percentage of inhibition was 0.0% compared with treatment of the pathogenic fungus R.solani, Beta amino were achieved. Butyric acid (BABA) 800, 1200, 1600 mg. L-1 not were achieved inhibition. The percentage of inhibition against fungus R.solani, where percentage of inhibition was 0.0% for all concentrations, and the results of field tests for studied factors (percentage of infection, severity of infection) and methods of use (M1 submerged the tubers two hours before planting, (M2): spraying plants after they were formed 10 leaves, (M3): The plants were sprayed again after 15 days of treatment M2 and the interaction between treatments and methods of using them. Treatments and methods of using and the interaction between the treatments and methods of using achieved a significant reduction in percentage and severity of infection, compared to treatment of pathogenic fungus R.solani, which had percentage and severity of infection 100 and 62.5% respectively.