The Effect of Local Triazine Restriction Policies on Recommended Weed Management in Corn

The potential health hazard posed by pesticides has raised public concern about their use. Herbicides are the most heavily used pesticides. As the most commonly encountered pesticide in groundwater, atrazine is especially troubling. Although its mammalian toxicity is low, atrazine causes concern because surveys have detected it in U.S. groundwater more often than any other herbicide (Hallberg; United States Environmental Protection Agency (EPA) 1990, 1992). Atrazine metabolites may be equally toxic and have also been detected in groundwater. In midwestern corn production areas, early summer concentrations of atrazine in surface water sometimes exceed EPA tolerance levels for drinking water (Ribaudo). Not coincidentally, atrazine is the herbicide most commonly used in U.S. corn and sorghum production. Herbicides are more likely than other pesticides to enter ground and surface water because: (1) they are applied at higher rates than other pesticides; (2) many are applied directly to the soil in pre-plant incorporated or pre-emergence treatments; and (3) even post-emergence treatments are usually applied when crops and weeds are small and much soil is exposed. Where spray rigs are dumped or washed out, herbicides can create point source contamination in addition to the non-point contamination associated with normal chemical crop treatment. The Federal Insecticide, Fungicide, and Rodenticide Reform Act of 1988 mandates the reregistration of all pesticides that were originally registered by the federal government for agricultural use prior to 1985. Atrazine is one such pesticide. Failure to pass reregistration for any specific use (on corn, for example) would have the same economic effect as a ban.