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Updates on water quality monitoring and best management practices for chlorpyrifos and other agricultural insecticides

by Robert Koch, Extension Entomologist (University of Minnesota) and Jamison Scholer (Minnesota Department of Agriculture)

The Minnesota Department of Agriculture (MDA) monitors surface and groundwater throughout the state for water quality impacts resulting from pesticides. Between 2010 and 2015, chlorpyrifos (active ingredient in Lorsban, Cobalt, Dursban, Nufos, Yuma and others) has been detected seasonally in several rivers and streams located in agricultural areas of Minnesota.

The MDA’s website provides an overview of the monitoring program and summary of monitoring results. In the 2014 results, some MDA samples had concentrations greater than water quality standards established by the Minnesota Pollution Control Agency (MPCA) to protect aquatic life. Based upon detections in 2015, and in previous years, it is likely that the MPCA will propose an updated list of water bodies considered impaired by chlorpyrifos in the near future. The MDA determined chlorpyrifos to be a “surface water pesticide of concern” and published a series of best management practices (BMPs) for agricultural insecticides in general and for chlorpyrifos. The BMPs help users follow mandatory label requirements and provide integrated pest management (IPM) recommendations to reduce insecticide input. Label use requirements & setbacks are legally enforceable. Recommendations not included on insecticide labels are voluntary. However, the MDA documents note that "if the voluntary BMPs are proven ineffective, mandatory restrictions on chlorpyrifos use and practices may be required." A summary of the BMPs can be found in a previous Crop News posting.
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