Antagonistic Potential of Iranian Native Streptomyces Strains in Biocontrol of Pythium aphanidermatum

摘要

Pythium aphanidermatum, the major phytopathogen induce damping off, root and stem rots, blights of grasses and fruit and in greenhouse cucurbits growing all areas of the world. Soil Actinomycetes including 178 isolates were assayed for assessing antagonistic activity against P.aphanidermatum. From tested isolates, 43 isolates were effective but 2 isolates strains 311 and 321 showed high anti-fungal activity revealed by bioassays in agar disk and well diffusion methods. For further biological characterizations, the active strains were grown in submerged cultures to determine growth curve and prepare crude extracts. Preliminary greenhouse studies indicated that amending soil with these strains, 311 and 321; reduce crop losses due to the pathogen. Antifungal activities of both antagonists were of fungicidal type on pathogen with complete inhibitory effects.