Effectiveness of potting media steaming in constraining growth of soil borne pathogenic fungi

Abstract

Most of the diseases affecting plant nurseries are soil borne and to eradicate the pathogens from growing media different sterilization (chemical, solar and steam) techniques are used. Steam sterilization is more efficient and environmentally friendly technology. To test the effectiveness of steam sterilization in controlling growth of fungal pathogens, different fungal species were isolated from various potting media (soil, sand, silt, FYM and coconut coir) pre and post steam sterilization and the isolates were characterized. Pre-sterilization fungal isolation was performed using serial dilution method which revealed different fungal species i.e., Aspergillus flavus, A. niger, Fussarium solani, Penicillium spp, Rhizoctonia spp, Curvularia spp, and Pythium spp. After sterilization, one group of potting media was kept open and the other one was tightly packed and placed at ambient temperature. These open and covered media types were evaluated for fungal regrowth by isolation after 7 days, 15 days and 30 days intervals. Different fungal contaminants were found in the potting media that was kept opened after sterilization. However, interestingly no soil related fungal pathogens were observed in the packed potting media 30 days post sterilization. These findings extended the current knowledge of steam sterilization of potting media and suggest that steam sterilization can effectively eliminate the fungal pathogens from the media. Further, it could be effectively used to produce sanitated plant nurseries and minimize the spread of soil borne diseases.