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 –Trap nutrients –Reduce algae –Reduce resuspension

Functions of Native Plants Natural Scenic Beauty

Natural Shorelines vs Sand Parking Lots

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

N EW S N EW S N EW S EWM range in Wisconsin 1960s1980s1990s

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

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

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

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

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

EWM Management Phases

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

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

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

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

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

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

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)

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

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 Environmental Assessment required

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

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

Sonar Specific Information Breaks down accessory pigments Cost varies $300-$600/acre Kills plants in 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.

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

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

Potter’s Lake Fluridone Conc’n

Potter’s Lakes Plants

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

Web Resources (non-profit) aquat1.ifas.ufl.edu/ www4.coastalnet.com/24d/