Suppression of Soilborne Plant Pathogens by Cruciferous Residues

Soilborne plant pathogens case heavy losses in many agriculturally important crops. The inoculum density of soilborne plant pathogens increases with increased years of cultivation of susceptible crops, and the inoculum density is directly proportional to the disease intensity in the field. In severe cases, total devastation forces aggrieved farmers to either abandon the land or shift to less susceptible but often less profitable crops. Therefore, effective control measures need to be developed that are economically, environmentally and technologically effective and acceptable. At present growers in many developing countries are dependent on cultural control measures for the partial reduction of soilborne plant pathogens. Among management strategies, use of organic amendments as crop residues, composts or manures has been found to be of wider acceptance and practical relevance in most of the agricultural production systems. The incorporation of plant residues in soil as green manure or at the end of crop growth has been a common practice for years. Higher plants contain and release an enormous variety of biologically active compounds, some of which have been exploited as potential pesticides. Use of cruciferous residues or making crucifers as a part of rotation will not only provide reasonable control of these pathogens but may also improve population of antagonists in soil, which will induce soil suppressiveness.