SPATIAL MODELING OF THE INFLUENCE OF CORN PLANTING AND WIND BLOCKING FEATURES ON CATCH OF HELICOVERPA-ZEA (BODDIE) IN PHEROMONE TRAPS AND SUBSEQUENT PEST DAMAGE

A spatial model of capture of Helicoverpa tea (Boddie) males in pherom one traps was developed as a UNIX script file running geographical inf ormation system commands (GRASS, v. 4.0). This model was developed to explain how spatial patterns of corn planting and wind-blocking featur es act to modify pheromone-trap-based earworm damage predictions on sw eet corn. In the model, we sought to create a modified cumulative moth catch value that correlated more strongly with subsequent pest damage than unmodified cumulative trap catch values. The model looks at dail y changes in wind direction and pheromone plume movement, calculates c ontribution to catch levels for all locations around the trap, and mod ifies the catch so that it only includes moths within the planting are a of interest. We describe this model in detail and show field data re sults from 2 years. (C) 1997 Published by Elsevier Science Ltd.