IMPORTANCE OF PHYSICAL AND CHEMICAL SOIL PROPERTIES IN THE SUPPRESSIVENESS OF SOILS TO PLANT-DISEASES

A critical review of literature is given on the role of the physicoche mical soil properties, such as texture, structure, moisture, predomina nt clay type, pH, Ca, suppressiveness of soils to diseases caused by A phanomyces spp., Fusarium oxysporum, F. roseum, F. solani, Gaeumannomy ces graminis, Phytophthora spp., Plasmodiophora brassicae, Pythium spp ., Rhizoctonia solani, Sclerotium spp., Streptomyces scabies, Thielavi opsis basicola, and Verticillium spp. The mechanisms proposed to expla in the influence of soil properties on disease suppressiveness and the lack of knowledge in this field are discussed. No general relation va lid for all diseases can be found. However, only few diseases have bee n intensively studied and important soil properties, such as the predo minant clay type or content and quality of organic matter, are often n eglected. Understanding soil suppressiveness is important for efficien t control of plant diseases with biological control agents.