Impact of pesticides on Trichoderma harzianum and on its possible antagonistic activity against Fusarium oxysporum under In vitro conditions

In vitro study was conducted to evaluate the effect of fourteen selected pesticides including six fungicides, four insecticides and four herbicides on the growth of a local strain of Trichoderma harzianum and on possible antagonistic activity of the treated fungus against Fusarium oxysporum. For compatibility study, each pesticide was tested at seven concentrations using poisoned food technique. While for the antagonistic activity study, treated T. harzianum was tested against F. oxysporium using dual culture technique under laboratory conditions. Significant differences were observed between the pesticides and the concentration used in the inhibition of mycelial growth and the inhibition increased with concentration increase. None of the concentrations tested of wettable sulphur, copper oxychloride, diazinon, cypermethrin, oxamyl, tribenuron-methyl and metribuzin suppressed the mycelial growth and the antagonistic potential of T. harzianum against F. oxysporium indicating the possibility of the integration between these pesticides and T. harzianum without any fear. However, the use of incompatible pesticides at all tested concentrations such as penconazole, iprodione, fenarimol and mancozeb and high concentrations of oxyfluorfen, glyphosate and imidacloprid may lead to inhibition of the growth and the antagonistic activity of T. harzianum as well as caution must be taken when using these pesticides in the disease management program. The obtained results will enable choice of combining T. harzianum with the selected pesticides within integrated disease management strategy.