Utilization of Trichoderma harzianum Rifai as biological control agent of Rhizoctonia solani Kuhn causing damping-off of selected vegetables in Nueva Ecija
2008
Bayugan, M.A., Instructor/Assessor, Quezon National Agricultural School
Biocontrol activity of Trichodrma harzianum applied as agar plug (42.3x 10-6) on phytopathogen Rhizoctonia solani resulted in a significant decrease of disease severity on damping-off in tomato, pechay and stringbeans by 66%, 57% and 59%, respectively. A decrease on the incidence of damping-off was also noted on tomato, pechay and stringbeans by 54%, 36% and 31% respectively. Dual culture test confirmed the findings in pot experiment that T. harzianum effectively controlled R. solani when it inhibited the radial growth of the pathogen in tomato, pechay, and stringbean by 42%, 36% and 22% respectively. isolates from stringbean had some form of resistance from the antagonistic activity of T. harzianum because of less percentage of radial inhibition. Antagonistic activity of T. harzianum was demonstrated by coiling and degrading the cell walls of R. solani which limited its growth and activity. Test on volatile metabolites suggested that inhibition of mycelial growth of R. solani was due to fast colonization and production of T. harzianum spores, and the production of enzymes as well as antibiotics. Radial growth of R. solani from tomato, stringbeans, pechay with T. harzianum was 19%, 52% and 67%, respectively. Hyphal fusion of R. solani isolated from three vegetables resulted in killing reaction (C2) from all pair combinations indicating distinct individuals but belonging to the same anastomosis group (AG).
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