Determination of the efficiency of sometrichoderma species against important stem rot agents of sunflower

Significance of sunflower plant as an industrial crop increases day by day. Stem rot disease is among the most important problems of sunflower cultivation. Although chemical control is the most common method used against the disease, biological control gained importance in recent years, because of the negative side effect of pesticides against human health and environment. In this study; in vitro and in vivo efficiency of Trichoderma atroviride, T. hamatum, T. harzianum and T. longibrachiatum against Sclerotinia sclerotiorum, S. minor and Macrophomina phaseolina, causing stem rot disease on sunflower, was investigated. As a result of in vitro trials, T. atroviride was found as the most effective antagonist against three stem rot pathogens of sunflower. In vivo studies showed that T. longibrachiatum was more effective against M. phaseolina and S. minor, while S. sclerotiorum was more efficiently suppressed by T. harzianum. In terms of plant growth parameters, all Trichoderma applications caused increase on the growth parameters of sunflower plants, when compared to controls. Similarly, all applications caused increase in total phenolic contents of sunflower plants when compared to control groups. The highest total phenolic amounts were found at the estimations made at 48th hour after inoculations, in all applications. As a result of the study, it was found that all antagonists could activate resistance mechanisms in sunflower plants against three pathogens.