Primary Study On Control Efficacy Of Soil-borne Plant Diseases With Mixtures Of Antagonistic Chaetomium And Trichoderma

Chaetomium globosum ND35 is a dominant endophytic fungus strain isolated from healthy Populus tomentosa. It has strong inhibition of many pathogens in vitro. Trichoderma spp. are important biocontrol agents which play a very important role in biological control of plant diseases. However, biocontrol efficacy of single antagonistic fungal strain is not stable in application. Control efficacy against Rhizoctonia damping-off and Pythium root rot of four vegetables have been preliminarily investigated with each single antagonistic fungal strains and their mixed fungal strains of C. globosum ND35, Trichoderma harzianum T88, T. atroviride T95. This lay a foundation for exploration and application of mixtures of antagonistic fungal strains in control of plant diseases in future.The results showed antagonism in varying degrees of single antagonistic fungal strains and their mixed fungal strains of C. globosum ND35, Trichoderma harzianum T88, T. atroviride T95 against Pythium aphanideramtum Pa and Rhizoctonia solani Rs in dual culture. The strongest inhibitions of P. aphanideramtum Pa and R. solani Rs were the antagonists combination of T88+T95 with 76.36% and 88.13%, respectively. Their inhibitions were higher than that of single strain of T88 and T95. And inhibition of Pa and Rs by the combination ND35+T88 and ND35+T95 were higher than that of single strain of ND35. The results indicated that biological control efficacy of Rhizoctonia damping-off and Pythium root rot of different vegetables by mixtures of each two antagonistic fungal strains ware higher than that of single antagonistic fungal strains. Control efficacy of the two soil-borne plant diseases by the combination ND35+T88 was the highest, the combination ND35+T95 was secondary, the combination T88+T95 was the lowest.In different soils, control efficacy of Rhizoctonia damping-off and Pythium root rot by mixtures of each two antagonistic fungal strains ware higher than that of single antagonistic fungal strains. Either mixtures or single of antagonistic fungal strains, control efficacy of Rhizoctonia damping-off and Pythium root rot in nutrient soil as substrate was the highest, that in sand soil as substrate was secondary, that in clay as substrate was the lowest.Control efficacy of two soil-borne plant diseases by inoculation with mixtures of each two antagonistic fungal strains and pathogens was better than that of inoculation with single antagonistic fungal strain at the same time, 1 day and 2 days before inoculation with pathogens. The earlier was inoculation with antagonist, the better was control efficacy of damping-off and root rot by antagonistic fungal strain.Control efficacy of two soil-borne plant diseases by mixtures of each two antagonistic fungal strain cultured in wheat bran medium and maize powder medium was better than that of single antagonistic fungal strain, respectively. And wheat bran medium was better than maize powder medium for control efficacy.The results of experiment in field demonstrated that the best control efficacy was the combination ND35+T88 with 62.84% and 56.03%, the secondary was the combination ND35+T95 with 60.37% and 49.05%, the lowest was the combination T88+T95 with 55.51% and 45.81% for Rhizoctonia damping-off and Pythium root rot. And biological control efficacy of Rhizoctonia damping-off and Pythium root rot by mixtures of each two antagonistic fungal strains ware higher than that of single antagonistic fungal strains. But there was some difference in compared with control of chemical fungicide.