In vitro study of Trichoderma isolates – potential antagonists of Sclerotinia sclerotiorum and other soil pathogens causing root and stem rots on pepper (Capsicum annuum L.)

Abstract

White mold Sclerotinia sclerotiorum (Lib.) de Bary is a potentially serious disease of pepper (Capsicum annuum L.) grown in unheated greenhouses. Control of Sclerotinia sclerotiorum is difficult due to lack of Capsicum spp. resistance towards this pathogen. Currently, among the registered fungicides there is none that can combat this pepper disease. The isolation and selection of local strains of antagonistic microbes is part of the strategy to combat pathogens by means of alternative methods. In vitro studies have been carried out on soil isolates of Trichoderma spp. regarding their antagonistic activity on the pathogen Sclerotinia sclerotiorum. All isolates were found to have a higher ability to compete with the phytopathogen for the food substrate. The competitive ability coefficient of Trichoderma spp. isolates varies widely – from 1.2 to 11. Among them, an isolate with pronounced antagonistic activity and a competitive ability coefficient of 10.8 stands out. The isolated fungus was identified as Trichoderma viride based on the cultural and morphological characteristics. The isolated strain was found to have high in vitro antagonistic activity not only against Sclerotinia sclerotiorum but also against various pathogens causing root and stem rot of pepper such as Botrytis cinerea, Verticillium dahliae and Rhizoctonia solani. The results of the current study showed that Trichoderma viride (Trv) has the potential to be used for production of biopreparation intended to control Sclerotinia sclerotiorum and other soil-borne pathogens in greenhouses. Keywords: antagonistic fungi, in vitro screening, antifungal activity, biological control, white mold, Capsicum annuum