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PREDICTING RISKS TO WILDLIFE FROM THE OFFTARGET MOVEMENT OF HERBICIDES
Citation:
Pfleeger, T G., E H. Lee, AND G. A. King. PREDICTING RISKS TO WILDLIFE FROM THE OFFTARGET MOVEMENT OF HERBICIDES. Presented at ASTM Symposium on Landscape Ecology and Wildlife Habitat Evaluation, Kansas City, MO, April 7-9, 2003.
Description:
While insecticide applications are generally thought of as the greatest pesticide risk to wildlife, the recent literature would suggest the indirect effects of herbicides on wildlife are much greater. The resulting alteration of habitat and decrease in food sources from the off target movement of herbicides leads to increased foraging time and therefore more opportunities for predation, especially of juveniles. The current test protocols for pesticide registration in the United States requires two tests for the protection of nontarget plants, seedling emergence and vegetative vigor. These tests are performed on ten agricultural annual species and are completed within 21-28 days of seedling emergence. These tests and test species have been determined to be inadequate for the protection of plant resources by several different groups of scientists. The tests are of limited duration and do not include critical life stages of plants especially reproduction. The test species are limited taxonomically and ecologically and in most cases do not represent species that are likely to be exposed. A new methodology is being developed which will incorporate native plants along with crop plants, perennials and woody species into the test scenarios. A geographical information system (GIS) is being used to identify areas and plant species at highest risk from herbicide drift. Habitat requirements of wildlife species in the areas at risk are identified. Plant species composing those habitats are tested for herbicide effects at critical life stages including reproduction. Examples will be presented from the midwest corn belt and from central California.