Abstract

Various cultural practices, including the use of cover and rotational crops, composts, tillage systems, and others have been promoted as management options for enhancing soil quality and health. All cultural practices are known to directly or indirectly affect populations of soilborne pathogens and the severity of their resultant root diseases. Number of products formulated with plant products and extracts are harmful to plant pathogens and maintain soil fertility. The mechanisms by which container media, organic amendments, and plant extracts affect plant pathogens can be simple or complex depending on the product and the pathogen. In some cases, control is achieved by direct killing of the pathogen propagules. In other cases, disease suppression is the result of a combination of multiple factors, including direct poisoning of the pathogen and indirect effects by enhancing microbial activity and improving vigor of plants. Thus, there is a great need to assure that the introduced soil management practices to improve soil quality will also result and maintain a healthy soil. The latter include the abundance and diversity of total soil microbes, high population of beneficial organisms and low population and/or activities of crop pests.

Key words: Plant extracts, sustainable agriculture, plant disease, soil amendments.