Components and Techniques of Integrated Pest Management Threshold Determinations for Soilborne Pathogens. Howard Ferris, Professor, Division of Nematology, University of California, Davis 95616. Plant Dis. 71:452-455. Accepted for publication 20 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0452.

Thresholds are levels of pest and pathogen stress to a crop that are used as a basis for management decisions. By definition, the threshold has an underlying economic basis and is a function of the relationship between the biological stress and crop value and the relationship between cost and stress reduction. Development of threshold levels usually involves determining parameter values for models that describe these relationships. The nature of the models may vary with the length of the planning horizon and the volatility of the biological systems involved. Parameter values are affected by biological, economic, and environmental conditions of the production system.