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Eurasian Water Milfoil

Eurasian Water Milfoil. Presentation Topics. Chapter 1 Functions and Benefits of Native Aquatic Plants Chapter 2 History and Impacts of Eurasian Watermilfoil Chapter 3 Managing Eurasian Watermilfoil. Functions of Native Plants. Fish and Wildlife Food Habitat Reproduction Water Quality

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Eurasian Water Milfoil

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  1. Eurasian Water Milfoil

  2. Presentation Topics • Chapter 1Functions and Benefits of Native Aquatic Plants • Chapter 2History and Impacts of Eurasian Watermilfoil • Chapter 3Managing Eurasian Watermilfoil

  3. Functions of Native Plants • Fish and Wildlife • Food • Habitat • Reproduction • Water Quality • Trap nutrients • Reduce algae • Reduce resuspension

  4. Functions of Native Plants • Natural Scenic Beauty

  5. Natural Shorelines vs Sand Parking Lots

  6. Exotic Eurasian Water Milfoil • 13 Native Species of Milfoil in Wisconsin • EWM Native to Asia and Europe • EWM Arrives in Wisconsin in 1960s

  7. N N N W W W E E E S S S EWM range in Wisconsin 1960s 1980s 1990s

  8. Out Competing Native Plants • Reproduction by Fragmentation • Begins to grow at colder temperatures and lower light levels • Possess canopy growth pattern • Not susceptible to native pathogens or herbivores

  9. Negative Impacts of EWM • Recreation • Reduced Biodiversity • Poor Fish & Wildlife Habitat • Thermal Stratification • Oxygen Stratification

  10. Managing Eurasian Watermilfoil in Wisconsin Lakes Bureau of Fisheries Management and Habitat Protection

  11. Chemical Selective Contact Mechanical Manual Harvesting Dredging Biological Weevil Physical Drawdown Bottom Barriers EWM Control Methods Generally Used in WI

  12. Regulations • All chemical applications regulated by NR 107 • Mechanical harvesting not regulated, but must collect cuttings • Weevils require a stocking permit • Drawdown, dredging and barriers require Ch. 30 permit

  13. EWM Management Phases

  14. Monitor and Quarantine • Low cost option • Unknown risk of continue spreading of plant • Critical to use quantitative measures • Markers and/or buoys require local ordinance approval

  15. Manual Raking/Pulling • Can be fairly selective and effective if roots are removed • Fragments must be collected • Labor intensive • Ongoing maintenance method

  16. Drawdown • Limited applicability • Requires 2-3 months of freezing conditions • Permits required • Low cost if available • Near shore areas only • Environmental Impacts?

  17. Mechanical Harvesting • Quick and immediate control • No use of pesticides • $200-$400/acre • Does take some fish, etc. • Milfoil control lasts 2 wks • Not applicable in shallows

  18. Dredging • Environmental disruptive and extensive permits required • Plant control generally a secondary benefit of project • Must go deep enough to prohibit growth • $5-$10 cubic yard or • $4,000 - $8,000 to remove five feet from 5 acres

  19. Milfoil Weevil • Commercially available from Ohio company • Costs ~$1/weevil, plus consulting costs • WI weevil project not promising after 3 years • Most useful as a long-term control method of heavy infestations

  20. Weevil Specific Information • Commercial stocking rates of 1,000 weevil/area • Literature suggest densities need to exceed 2 weevils/stem before damage is noticeable • Eagle Spring (Walworth County): Spent $9,000 dollars stocking approximately 5,000 weevils. Little or no damage noticed. More stocking is proposed by company • WI Weevil Lakes (12 state wide): Continue to document changes in the milfoil. Some milfoil have declined even more since last year (two years after stocking)

  21. Selective Chemical Treatment • 2,4-D selectively controls dicot aquatic plants • Sonar selectively controls some plants a low concentrations • Diquat, Aquathol-K, Endothall are broad spectrum herbicides

  22. Chemical Treatment Criteria • Compliance with NR 107 • No or little impact to majority of native species • Acceptable risk to susceptible species • Minimal water movement • Community consensus • Aquatic Plant Management Plan or an EnvironmentalAssessment required

  23. 2,4-D Specific Information • Growth hormone & systemic • $300 +/- per acre • Kills plants in 10-14 days • Used for shoreline and cove treatments • Water use restrictions for domestic use, irrigation and livestock watering • Control difficult ifgroundwater flow present Controls: Waterlily, Coontail, Milfoils, Bulrushes, and other dicots

  24. 2,4-D Treatment Projects • Beulah Lake (Walworth County): Initially compared barriers to 2,4-D on 2 acre sites. In four years, despite aggressive treatment with 2,4-D, treatments have expanded to 9 acres. • Delavan Lake (Walworth County): Treated large (20 acres) cove area. Control lasted one season, but treatment required in 2nd year. • Pine Lake (Waukesha County): Have been using 2,4-D products for shoreline treatment for at least 5 years. Minor evidence of native plant re-growth, but similar shoreline areas are treated each year. • Mendota/Monona Lakes (Dane County): 2,4-D not allowed by public consensus due to concerns about carcinogenic properties. Selective WI treatments

  25. Sonar Specific Information • Breaks down accessory pigments • Cost varies $300-$600/acre • Kills plants in 20-60+ days • Restricted to cove or whole lake treatments • Requires an Aquatic Plant Management Plan • Irrigation water use restrictions Controls: Elodea, Coontail, Milfoils, Naiads & Curlyleaf at concentrations of 5-8 ppb. Kills many natives above 15 ppb.

  26. Sonar Treatment Strategies • Split treatments with Granular Product: Treatment application is split into three equal parts (for example 15 ppb every two weeks). This provides for a longer exposure time at a lower concentration. Useful for coves but not practical for whole lake treatments. May take a long time for control (Delavan: 60 plus days). • Spring Whole Lake Treatments: Have been used extensively in Michigan (~23+), and a few in Minnesota (~3). Michigan limits concentrations to < 8 or 5 ppb. Bump treatments are more effective. • Fall Whole Lake Treatments: Less than 10 done nationwide. Timing allows for higher dose (10-12 ppb) that may possibly less impact natives less. Selective treatments

  27. Sonar Treatment Projects • Small Ponds (Southeast Region): A number of County Park ponds have been treated with concentrations ranging from 10 ppb to 15 ppb. Treatment effective for 1 to 5 years, depending on conditions. • Delavan Lake (Walworth County): Conducted three, split treatments over a large (35 acres) cove area. Control lasted two seasons to date. • Potters Lake (Walworth County): After preparing an Aquatic Plant Management Plan and demonstrating public support, conducted a whole lake, fall treatment at 15 ppb. Milfoil controlled for two years to date, but natives heavily impacted due to long residency time Selective WI treatments

  28. Potter’s Lake Fluridone Conc’n

  29. Potter’s Lakes Plants

  30. Secrets to Controlling EWM • No Silver Bullet • Develop Comprehensive Aquatic Plant Management Plan • Build consensus for project • Plan for maintenance and money

  31. Web Resources (non-profit) • www.nalms.org/ • aquat1.ifas.ufl.edu/ • www.wes.army.mil/el/aqua/ • www.apms.org/index.html • www4.coastalnet.com/24d/ • www.dnr.state.wi.us/

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