Saprophytism and pathogenicity of Rhizoctonia solani Kühn AG-4 in soil amended with coarse castor bean meal

Abstract

Amendment effects of coarse castor bean meal into soil on the survival of Rhizoctonia solani (Fungi), as well as on the severity of its attack on bean plants Phaseolus vulgaris (Leguminosae-Faboideae) have been evaluated in a greenhouse. The soil was amended with coarse castor bean meal and infested concurrently. Only fungus was introduced in non-amended soil. Beanstalk baits were buried and bean seeds were sown on the same day, and on 0, 10, 20, and 30 days after infestation and amendment. Survival of R. solani was determined by observing development of bean stalk baits recovered, 4 days after soil exposure, and placed on water-agar medium + oxytetracycline. The plants were recovered 15 days after each sowing date and evaluated for disease severity on a 0-5 scale. The amendment of coarse castor bean meal into soil increased both saprophytic development and disease severity of R. solani