Impact of soil health management practices on soilborne pathogens, nematodes and root diseases of vegetable crops

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. Soil biology is a major component and contributes significantly to soil quality and productivity. The major activities of soil microbes include the decomposition of organic materials, mineralization of nutrients, nitrogen fixation, suppression of crop pests and protection of roots, but also parasitism and injury to 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. Production of vegetables and other food crops is often significantly affected by several soilborne pathogens that require control. The incidence and severity of root diseases is an indirect assessment of soil health for specific commodity/soil use. In addition, understanding and selecting the appropriate cultural practices that limit or prevent damage of root diseases is essential for the long-term and sustainable management of soil quality and health. Case-study examples are presented to illustrate the impact of cover crops and their green manures on the density and damage of root-knot and lesion nematodes to vegetables; and also tillage, soil amendments, crop rotation, and cover crops on bean yield and root rot severity. (C) 2000 Elsevier Science B.V. All rights reserved.