Pest damage relations at the field level

Abstract

In view of large yield losses to various biotic pests, there is a critical need to adapt crop models to account for pest effects, either by direct coupling with mechanistic pest simulators, or by input of observed pest damage or numbers. Pest effects can be coupled to crop models by modifying crop state variables (mass or numbers of various tissues), rate variables (photosynthesis, water flow, senescence), or inputs (water, light, nutrients). An approach is presented whereby scouting data on observed pest damage is input via generic pest coupling modules in order to predict yield reduction from pests. Examples of this approach are presented for simulating the effects of defoliating insects, seed-feeding insects, and rootknot nematode on soybean growth using the SOYGRO model. A similar approach with the CERES-Rice model is used to simulate effects of leaf blast and other pests on rice growth and yield. Effects of leafspot disease on peanut growth and yield are illustrated with both the generic pest coupling approach and a mechanistic disease simulator coupled to the PNUTGRO model. A systematic approach to input pest damage effects into crop models offers potential to account for yield loss from pests and to determine action thresholds that are dynamic and different per season or region.