The in vitro effect of certain fungicides, insecticides, and biopesticides on mycelial growth in the biocontrol fungus Trichoderma harzianum

The in vitro effect of certain fungicides, insecticides, and biopesticides on mycelial growth of Trichoderma harzianum was evaluated. Seven systemic fungicides, 2 contact fungicides, and 4 biopesticides were tested. A progressive increase in percent inhibition of radial growth in the fungus was observed as the concentrations of the fungicides increased. Among the systemic fungicides, hexaconazole was the most toxic, followed by propiconazole and triflumizole. Toxicity of the contact fungicides was lower than that of the systemic fungicides, among which copper oxychloride and copper hydroxide were highly compatible; no inhibition was observed at lower concentrations. In terms of the insecticides tested, quinalphos and dicofol exhibited toxicity (quinalphos more so), even at the low concentration of 10 ppm. Endosulfan, fenpropathrin, and propargite were less toxic, which indicated the compatibility of these insecticides with T. harzianum. A varying level of inhibition was observed in response to the biopesticides. Although neem-based biopesticides completely inhibited the growth of the biocontrol strain, ovis was compatible with the growth of Trichoderma harzianum. The present results will help delineate the possibility of combining T. harzianum biocontrol agents and agrochemicals for use in an integrated pest management approach.