标题：Antagonistic activity of Trichoderma harzianum and Trichoderma viride strains against some fusarial pathogens causing stalk rot disease of maize, in vitro
摘要：AbstractObjectivesA high incidence of stalk rot disease of maize causes huge economic losses as well as deleterious effects on the environment and human health resulting from fungicide use. Against this background, the current study was established to evaluate the antagonistic efficacy ofTrichoderma virideandTrichoderma harzianumstrains againstFusarium proliferatumandFusarium verticillioidesstrains, the most common causative agents of stalk rot disease of maize.MethodsDual culture assay was performed to determine the antagonistic efficacy ofTrichodermastrains against some fusarial pathogens of maize. Mycoparasitic relationships of the antagonistic fungal strains against fungal pathogens were investigated using a slide culture technique. Furthermore, a food poisoning technique was performed to detect the antimycotic efficacy ofTrichodermaculture filtrates against fusarial pathogens of maize. Antifungal activity of organic solvent extracts ofT. harzianumandT. viridewas evaluated using the disc diffusion method. GC–MS analysis was used to detect the active components of these extracts.Results and conclusionTrichoderma virideshowed antagonistic activity againstF. proliferatumandF. verticillioideswith mycelial inhibition rates of 80.17% and 70.46%, whileT. harzianumexhibited rates of 68.38% and 60.64%, respectively. The culture filtrates ofT. virideandT. harzianumstrains exhibited antifungal activity againstF. verticillioidesstrain with suppressive rates of 56.7% and 32.2%, while the mycelial inhibition rates againstF. proliferatumstrain were 44.09% and 23.50%, respectively. Mycoparasitic action ofT. harzianumstrain against fusarial strains was detected, while no mycoparasitism was observed betweenT. virideand fungal pathogens. The fungicidal concentration of carbendazim fungicide againstF. proliferatumwas 2.00 ppm, whileF. verticillioidesstrain exhibited resistance to carbendazim fungicide. Moreover, the acetonic extracts ofT. virideandT. harzianumstrains exerted the highest antifungal potency againstF. proliferatumstrain, recording minimum inhibitory concentrations of 0.25 and 0.50 mg/ml, respectively. The main bioactive constituents of the acetonic extracts ofT. virideandT. harzianumstrains were palmitic acid (22.87%) and acetic acid (21.36%), respectively. In conclusion, the antagonistic strains could be a potential source of novel biological fungicides, especially against carbendazim-resistantF. verticillioidesstrain, avoiding side effects of chemical fungicides.
