The Enemy - Brazilian elodea (or egeria or ancharis) (Egeria densa) is a perennial aquatic broadleaf weed that inhabits numerous waterways throughout the United States. This plant was added to the noxious weed list in Idaho due to its ability to destroy lakes and rivers by out competing native habitat and by growing so thick that it destroys fish and recreation opportunities. The plant has four leaves to a whorl and are spiny leaves that occur on all sides of the stem. It produces white flowers that will bloom above the water surface.
The Strategy - Because this plant can spread by fragmentation, it can move from water system to water system on boats or trailers. Once established it roots into the soil below the water line and creates large mats of weeds that can stop boats and kill fish. The plant is usually introduced by someone dumping their aquarium tank into the water in hopes of their pet fish surviving in the wild. Not only does this introduce non-native fish but it also contaminates the water body with weeds. Since most plant are males, the primary methods of spreading is by fragmentation.
The Defense - PREVENTION IS KEY. Make sure your boats, trailers, and other water toys are clean of any debris before moving away from the dock areas. Hand harvesting has been known to be effective, although extremely expensive. There are a few herbicides that the EPA have designated as safe to use in these water systems and are very effective in destroying the concentrations of the weeds. Products such as Navigate, Reward, or even Sonar are the ones used to control the weed. Help us out by checking your aquarium and supply stores in ensuring that we are all doing out part to protect our natural resources. Clean, drain and dry all your equipment.
PLEASE NOTE - The proper use and application of herbicides can be an effective way to control and eradicate noxious and invasive plants. Before using herbicides, always carefully follow the label and safety instructions on the label. While we recommend the use of herbicides as one of the effective tools for integrated pest management, the Idaho Weed Awareness Campaign assumes no liability for herbicide applications.
For more information, click on the link below to download the Idaho's Noxious Weeds Control Guidelines publication produced by the University of Idaho Extension.
U of I Idaho's Noxious Weeds Control Guidelines (183 KB PDF download)