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Aquatic Plant Monitoring Contacts
Aquatic Plant Research > Invasives > Management and Control > Eurasian Watermilfoil (EWM) Control > Synthesis of Current Research on Control of Invasive Aquatic Species > Preliminary Report: Large-scale Use of the Herbicides 2,4-D and Endothall to Control Non-native EWM and Hybrid Milfoil in Wisconsin Lakes

Aquatic Plant Research Preliminary Report: Large-scale Use of the Herbicides 2,4-D and Endothall to Control Non-native EWM and Hybrid Milfoil in Wisconsin Lakes

DNR staff in conjunction with the Army Corps of Engineers formed a cooperative research agreement to learn more about the behavior of aquatic herbicide applications in a subset of Wisconsin lakes and flowages. Specifically, researchers focused on determining what 2,4-D and/or endothall concentration exposure times are needed under varying operational conditions to improve control of invasive species while minimizing native impacts. Based on the first two years of the study, we are focusing future whole lake 2,4-D treatments for Eurasian watermilfoil at target lake wide concentrations of 250-350 µg/L averaged throughout the first week of treatment. Concentrations of 2,4-D above 500 µg/L coupled with exposure times of multiple weeks resulted in decreased frequencies of occurrence of several native species. In small-scale treatments, herbicide concentrations 24 hours after treatment were well below the target concentrations due to fast dissipation of the herbicide off the treatment site. Researchers are compiling more treatments to determine what size treatment area is necessary for consistent results. Establishing guidelines for large and small scale treatments will help improve efficacy of target species while preventing damage to native aquatic plant communities. This report provides an update on the first years of the study and provides the basis for future research directions and guidance. DNR Science Services is preparing this report for publication which will provide the individual case studies as an important reference tool for managers.