Giant Salvinia

Giant Salvinia Guide

This free-floating aquatic fern can grow in almost any water system including lakes, streams, ditches, and wetlands. Giant Salvinia forms chains of leaves that link together into thick mats on the water surface. These mats restrict light and oxygen, shading out native plants and organisms and disrupting ecosystems.  Giant Salvinia can completely cover waterways restricting sunlight and oxygen that native plants, fish, insects and other species require.  It makes lakes and streams look like putting green, eliminating opportunities for boating and fishing.  Native to Brazil, this water fern was probably initially spread by its use in aquariums and garden ponds.  Salvinia leaves are oblong ½ to ¼ inches long and vary from green to gold to brown.  Leaves are arched with white hairs. Submerged fern fronds are stringy and root-like, but the plant has no real roots.  


Giant Salvinia reproduces by continuous branching and fragmentation of rhizomes that create new plants. Also, buds can lie dormant during periods of reduced moisture and cold temperatures and become new plants when conditions are optimal. Giant Salvinia can double in numbers in as little as 2-10 days under the right conditions. If you find salvinia please contact your local DNR. Due to its fast growth and invasive nature, it is illegal to transport Giant Salvinia on boat trailers, boat motors, or live wells. Therefore, watercraft owners are encouraged to clean boats and trailers before leaving salvinia infested water bodies. 

Physical/Mechanical Control

Giant Salvinia reproduces so rapidly that large-infestations are virtually impossible to eradicate by raking or pulling. However, small infestations can and should be controlled by hand immediately, before they get too big. 

Chemical Control

When used carefully according to the label instruction, aquatic herbicides can be safe and effective management tools.  The products that have been successful in treating fanwort are Sonar AS, Sonar RTU, Propeller, Shore Klearand Reward.  A nonionic surfactant Cygnet Plus should be mixed in solution with herbicides when plants are treated.

Sonar A.S. is a long-acting systemic herbicide ideal for water bodies with minimal flow. Simply mix Sonar A.S. with water and spray throughout the surface of the water or pour in different spots around the pond. Sonar A.S. does not have water use restrictions.

Sonar RTU is a long-acting, systemic, easy to use herbicide.  Sonar RTU does not require mixing, simply open the bottle and treat from the shoreline.

Propeller is a broad spectrum, fast acting contact algaecide/herbicide.  It comes in a water dispersible granule that mixes with water to be sprayed or pour. Propeller should be applied to actively growing plants or algal blooms.

Shore-Klear is a systemic herbicide that will translocate down into the root systems killing the plant.  Successful giant Salvinia management in heavily infested areas can take several years and sometimes annual maintenance spot treatments.

Reward is a registered diquat label for aquatic use.  This contact algaecide and herbicide quickly and effectively kills filamentous algae and all plant cells.

Cygnet Plus is a nonionic wetting agent, sticker, activator, and penetrant all in one.  Cygnet Plus increases the effectiveness of herbicides uptake into the plant tissue.