Effect of Population Density of Rhizoctonia solani on Biocontrol Ability of Trichoderma harzianum in Frenchbean

Effect of Population Density of Rhizoctonia solani on Biocontrol Ability of Trichoderma harzianum in Frenchbean

An attempt was made to assess the impact of Rhizoctonia solani population on the activity of biocontrol agent Trichoderma harzianum in French bean. An easy and effective method for artificial inoculation of R. solani was developed, which led to the development of clear and atypical symptoms of R. solani infection on French bean seedlings. Results of two experiments using varied inoculum doses of R. solani showed that seed biopriming with T. harzianum (Th-21) colonized Jhangora waste Th (J) was totally ineffective with respect to disease suppression at higher inoculum doses (1-15 g/ pot). Least per cent germination was recorded in Trichoderma treated seeds when sown at highest inoculum dose of 15 g/ pot. On the other hand, at lower inoculum doses (25-250 mg/ pot), same dose of bioagent was quite effective in suppressing disease and improving different planting value parameters. Significant decline in the disease suppressive efficacy of bioagent was observed with an increase in inoculum dose. Results conclude that pathogen population density in the rhizosphere had a marked influence on the activity of a biocontrol agent in soil...