Search

Josh Stamper, MDA, welcomed participants to the meeting, emphasized the importance of discussion and member feedback, encouraged members to reapply, and touched on revisions to the Pesticide Management Plan and MDA’s recent comments to the Environmental Protection Agency (EPA). PMPC Members and MDA leadership introduced themselves.

Kate Hall (meeting facilitator), MDA, went through housekeeping items and presented background slides on PMPC. The presentation provided an overview of the MDA’s Pesticide Management Plan, “common detection” and “surface water pesticide of concern” designations, and select comments received from members the previous year. The MDA’s Indigenous Land Acknowledgement statement was read. 

MDA Presenter: Bill VanRyswyk

The presentation provided an overview of the MDA’s monitoring program and introduced the main sections of the 2023 report. Changes to the 2023 analyte list were highlighted along with groundwater and surface water program design elements.

MDA Presenter: Dave Tollefson

The presentation focused on the surface water results from the 2023 monitoring season. Pesticide waterbody impairments were presented along with an overview of how Minnesota water quality standards are used to evaluate data. Current surface water pesticides of concern were reviewed, and trend maps were presented showing changes in detection frequency and concentration for individual PMRs. Comparisons of detected concentrations to relevant standards or guidance values (i.e., reference values) were also presented, focusing on pesticides detected at concentrations >10% and >50% of relevant reference values.

Discussion focused on:

• Pyrethroid insecticides
  • Testing of sediments and the potential additive effects of pyrethroid insecticides were discussed. The MDA does not sample sediments for pesticide residues, and pyrethroids are evaluated individually because only individual chemical aquatic life benchmarks are available. The potential importance of evaluating additive effects from pesticides with similar modes of action was further discussed along with the challenges of doing so.
• Neonicotinoid use
  • The percentage of corn and soybean seed treated with neonics was discussed. The MDA noted that an estimated 40% of soybean seed is treated with a neonic and 99% of corn seed is treated with a neonic.
  • Imidacloprid urban detections were also discussed in relation to its non-agricultural uses including residential lawn grub treatments and emerald ash borer management.
•  Toxicological basis for reference values
  • The toxicity data used to determine reference value concentrations was discussed with respect to the test species used, consideration for plants like wild rice and treaty protected resources, and the limitations of toxicity data for single chemicals. 
• Unspecified reference values for degradates
  • The lack of a chemical specific reference value was discussed in relation to pyroxasulfone M1, a degradate of pyroxasulfone. When a degradate-specific reference value is not available, the MDA will typically use the parent reference value. The EPA does not provide an aquatic life benchmark for pyroxasulfone M1, and data was not available through the EPA’s ecological risk assessment for the MDA to calculate a chemical-specific value.