Combination of biocontrol agents and chemical fungicides in controlling Fusarium oxysporum and Rhizoctonia solani pathogenic fungi

The fungicidal properties of  Rizolex-T, Moncut, Hesta,  Rolex, Vitavax  200 and Tazolen against two pathogenic soil borne fungi (Fusarium oxysporum and Rhizoctonia solani) grown on glucose-mineral salts agar media as well as three non-pathogenic biocontrol agents (Trichoderma harzianum, Tricodermaviride and Trichoderma virens) were investigated and the EC50 values  were calculated. The results indicated that both pathogenic fungi were more sensitive than the biological control agents all tested fungicides.  Although both Hesta and Rolex were more toxic against R. solani than
Rizolex-T according to the EC50 values, the sensitivity of R. solani toward Rizolex-T was obvious. However, all six tested compounds were more toxic of R. solani than F. oxysporum. The results exerted feeble toxic effect against the three fungal biological agents. Generally, the tested fungicides exerted higher fungicidal potency against both pathogenic fungi F. oxysporum and R. solani than the three biocontrol agents Trichoderma isolates. The interactions between the three isolates of Trichoderma and both pathogenic fungi indicated that the antagonistic activity was greatly influenced by the presence of the tested fungicides in the culture media at 300 ppm for any of the tested fungicides that all trichoderma isolates caused complete growth inhibition of both pathogenic fungi. Also combination of Trichoderma isolates in the presence of 200 ppm caused a very high inhibition degree with most cases of tested fungicides. Trichoderma isolates alone suppressed the growth of pathogenic fungi. The results clearly proved that increasing the concentration of all tested fungicides enhanced the antagonistic activity of Trichoderma isolates against the hyphal growth of both tested pathogenic fungi leading to lowering the EC50 values of tested fungicides in the presence of Trichoderma isolates , that leads to decrease of conventional fungicide chemicals released in the environment in order to control these pathogenic fungi .