Antagonistic activity of Trichoderma spp. against soilborne pathogens

Abstract

Potential use of Trichoderma spp. against different soilborne plant pathogens (Sclerotinia sclerotiorum, Rhizoctonia solani and Pythium aphanidermatum) was investigated in this study. Thirteen Trichoderma spp. isolates were derived from the rhizosphere of different host plants originating from seven localities in Serbia. Based on the results of preliminary tests, us-ing a dual culture confrontation method, four Trichoderma spp. isolates with the best antago-nistic activity were chosen for identification and further investigation. Morphological and physiological characteristics and sequence analysis of the translation elongation factor 1-alpha (tef 1), showed that all antagonistic strains belong to Trichodema harzianum species complex (ThSC). Antagonistic activity of the ThSC strains was quantified in vitro on PDA medium at 24°C, by a double-layer-well method. The highest antagonistic activity was achieved by T1 isolate against P. aphanidermatum and R. solani, where mycelial growth of the pathogens was completely inhibited. None of the ThSC strains was able to inhibit the growth of S. sclerotiorum under presented experimental conditions. To determine the mode of antagonistic activity, tree types of liquid ThSC culture filtrates were used: filtrated through cheese cloth (containing fungal spores), filtrated by syringe filters (spore free) and heated cheese-cloth-filtrate (10 min at 100°C). The research showed that T. harzianum strains exhibited direct my-coparasitism as the mode of antagonistic activity and that produced metabolites didn’t ex-press suppressive effect on pathogenic isolates. Presented study revealed that tested isolates of ThSC, or at least T1 strain, could be effective biocontrol agent(s) against R. solani and P. aphanidermatum.