Use of gleams to predict insecticide losses from pine seed orchards

Abstract

AbstractIntensive pine forest management practiced in the southern United States relies heavily on seed orchards to produce genetically improved seedlings to achieve high productivity. One of the most critical problems is the control of seed and cone insects requiring heavy and frequent applications of insecticides. Hydrologic modeling of insecticide fate in surface water and ground water is a useful technique for evaluating the environmental fate of the applied insecticides. The GLEAMS (groundwater loading effects of agricultural management systems) model was used to evaluate the differences between fate of insecticides at four pine seed orchard sites in different physiographic regions of the southern United States. A 50‐year simulation period was used. Insecticides selected for simulation were carbofuran, azinphosmethyl, fenvalerate, and permethrin. The simulations of insecticide losses in storm flow and percolate at each of the seed orchards demonstrated the importance of the time of application relative to precipitation occurrence, effective rooting depth, and soil‐water conditions. Although the absolute insecticide losses may not be accurately simulated by GLEAMS, the model can predict the seasonal patterns of loss and relative loss among different insecticides likely to occur under actual seed orchard conditions.