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

In vitrostudy 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 compatibilitystudy, each pesticide was tested at sevenconcentrations using poisoned food technique. While for the antagonistic activity study, treated T. harzianumwas tested against F. oxysporiumusing 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. harzianumagainst F. oxysporiumindicating the possibility of the integration between these pesticides and T. harzianumwithout any fear. However, the use of incompatible pesticides at all tested concentrations such as penconazole, iprodione, fenarimol and mancozeband high concentrations of oxyfluorfen, glyphosate and imidacloprid may lead to inhibition of the growth and the antagonistic activity of T. harzianumas well as caution must be taken when using these pesticides in the disease management program. The obtained results will enable choice of combining T. harzianumwith the selected pesticides within integrated disease managementstrategy.