Antagonism of Azotobacter chroococcum isolates to Rhizoctonia solani

Antagonism of isolates ofAzotobacter chroococcum toRhizoctonia solani on agar plates was studied, and isolates were tested for their ability to controlR. solani infection of potato sprouts in sterilized and unsterilized soil. The degree of antagonism exhibited varied strongly among the isolates and was also found to be temperature-dependent. At 25, 20 and 15°C, all but one strongly antagonisticAzobacter isolate effectively prevented infection of sprouts of potatoes planted in a soil heavily infected with a pathogenic isolate ofR. solani. At 10°C none was effective.