Theory and practice of the cropping systems approach to reducing nematode problems in the tropics.

Plant-parasitic nematodes are major constraints to the productivity of tropical farming operations. Intensive land use and climatic conditions favorable to nematode development contribute to increased crop losses due to these pests. Many farmers in developing tropical countries have limited resources and management options. Cropping systems research is a relatively low-cost, low-input method of optimizing existing agricultural practices with respect to limiting losses due to plant-parasitic nematodes. Specific tropical farming practices are discussed along with problems they pose for research in quantitative hematology. Comprehensive, systematic research methods for delineating and using nematode-host relationships are described, and new ways of dealing with complex multicropping systems are suggested.