Laboratory Study of Synergistic Effects of Mixtures of Organic Biocides, Metal Chelator and Antioxidant Materials against Rainbow White-rot Fungus

In this research, the individual and interaction effects of three organic biocides (propiconazole, tebuconazole, and chlorothalonile) with the metal chelator EDTA and the antioxidant BHT at different concentrations (50, 150, 250, 350, and 450 ppm) against the white-rot fungus, Trametes versicolor was investigated. In under laminar sterile hood, about 25 mL of the media was poured into the Petri plates. Three antibiogram discs (with triangular position) put on the media. By micro-sampler about 20 μL of steriled preservative solutions was poured on every disc, separately. Then, about 5 mm of mycelium plug of intended fungus that was inoculated previously was put in the center of plates. The plates were incubated and daily for one week, the mycelium growth of fungus and inhibition effects of different preservative solutions against fungus was measured. The results of this research demonstrated that chlorothalonil biocide by itself have not any inhibition effect on growth of fungus, whilst propiconazole and tebuconazole biocides by itself have significant effect at different concentrations on growth of fungus. In consider of synergistic effect of propiconazole, tebuconazole, and chlorothalonil biocides with non-biocides additives of EDTA and BHT, it has been found that there is synergistic effect between propiconazole biocide and the metal chelator EDTA at high concentration such as 450 ppm, but in combination with other solutions synergistic effect has not been found. Also, any synergistic effect has not found between tebuconazole and chlorothalonil biocides with other preservative solutions.