MONITORING & MANAGEMENT
European Frog-bit Management
Management of European frog-bit is essential to mitigate harm and ensure this aquatic invasive species does not continue to spread throughout the Great Lakes ecosystem. The European Frog-bit Collaborative has developed resources to aid managers including summarizing information on current management techniques.
Management Techniques
Hand-Pulling
Hand removal of European Frog-bit is generally used for smaller known populations and is labor intensive. Handing pulling is most effective in early spring to summer before the plant has had time to grow significantly. Removal by hand can be augmented by using small handheld rakes and by collecting plant material in feed bags that allow excess water to drain out, reducing the weight.
Mechanical Removal
European Frog-bit can be removed mechanically, typically with large equipment like a harvester.
Herbicide
Several different herbicides with varying modes and speeds of action have been used to treat European Frog-bit. Herbicides that have been used to chemically treat EFB include:
- Diquat
- Flumioxazin
- Endothall
A summary of different herbicides for EFB can be found in Table 2 of Cahill et al. 2021.
Shading
Covering a patch of European Frog-bit with a shade cloth can be effective at inhibiting growth and spread. By blocking essential light penetration the plant can no longer germinate and/or grow.
Biocontrol
While various insects, mollusks, rodents, birds and fish can feed on European Frog-bit, the approval process for release any of these organisms for EFB management has not yet occurred United States or Canada.
D.A.S.H.
Diver Assisted Suction Harvesting (D.A.S.H.) is a mechanical method for removing invasive plants. Divers identify and pull the plants, feeding them into a vacuum that sucks the material onto a boat for disposal. For European frog-bit (EFB) removal, this method is modified to exclude divers, as EFB is a free-floating plant. Instead, an individual operates the vacuum from the boat deck. This method does not remove turions that may have settled to the sediment.
Proper disposal methods
When physically removing EFB, be sure to properly dispose of removed plants. Locate and contact your relevant local, state, or provincial invasive species management organization using this Invasive Species Management Areas Lookup Tool to assist you in understanding proper EFB disposal methods. States may also have official resources, such as this guide from Michigan (specifically, see the section on aquatic plants).
Some safe disposal methods for EFB include:
- Double-bag plant material and transport to a local landfill (if permitted in your jurisdiction).
- Dry and burn the plant material away from waterbodies (if permitted in your jurisdiction).
- Compost or bury on dry land away from waterbodies (if permitted in your jurisdiction). This may be an option if you can assure that the resulting compost is not used near any wetlands or wet environments to prevent any regrowth of plant material or turions.
Resources & Publications
Twitter Image: Protect Habitat
European Frog-bit Collaborative
Twitter Image: Preserve Habitat
European Frog-bit Collaborative
Status and strategy for European frog-bit (Hydrocharis morsus-ranae L.) management
Michigan Department of Environmental Quality and Central Michigan University