Southeast Exotic Pest Plant Council Invasive Plant Manual
Common Name: Water Hyacinth
Scientific Name: Eichhornia crassipes (Mart.) Solms
Water hyacinth is a member of the Pontederiaceae or Pickerelweed/Water-hyacinth family.
Vegetative reproduction starts in the spring from over-wintering plants. Growth is initiated by the production of daughter plants. Growth continues until maximum biomass is achieved in the early fall.
Origin and Distribution
Water hyacinth is thought to be native to the Amazon River basin of South America. It was introduced to the United States in 1884 at the Cotton States Exposition in New Orleans, Louisiana. It spread across the southeastern U. S. and was identified in Florida in 1895. It was reported to be in California in 1904.
Current distribution includes all of the southeastern states, New York, Virginia, Kentucky, Missouri, Alabama, Texas, Arizona, and California. It has been listed as a Federal Noxious Weed and is prohibited or restricted in three states.
Water hyacinth may be confused with the aquatic free-floating frog’s-bit (Limnobium spongia). Frog’s-bit can be distinguished by it’s heart-shaped leaves that grow in a rosette. In addition, water hyacinth sometimes has a thick spongy leaf stem, which is absent on frog’s-bit. Frog’s- bit has silvery roots, compared to the dark, blue-black roots of water hyacinth.
Water hyacinth will grow in a wide variety of aquatic habitats including lakes, ponds, rivers, wetlands and marshes. It will grow most prolifically in water of high nutrient content; it has been used in wastewater treatment facilities. It can withstand drastic fluctuations in water level, flow rates, acidity and low nutrient levels. These characteristics make it a popular plant for residential water gardens.
Harvesting: Harvesting may control small initial populations. Where possible, hand pull all of the plant parts from the water. Plants should be bagged and disposed of. Since plant fragments can potentially start a new infestation, care must be taken not to break plants. Consistent monitoring for several growing seasons is required to control new or missed plants.
Foliar Spray Method: If water hyacinth covers a large area, a foliar spray can be applied using a 2% glyphosate solution or at a rate of 2 kg per ha plus 1% non-ionic surfactant. Since glyphosate is produced in a number of formulations, use a formulation labeled for aquatic use. Glyphosate is a non-selective herbicide, and extreme care must be taken to avoid contact with non-target plant species. Refer to manufacturer's label for specific information and restrictions regarding use.
Triploid Grass Carp: Sterile grass carp or white amur (Ctenopharyngodon idella) may be an option in areas with adequate control structures to ensure retention of released fish. Grass carp will eat a variety of vegetation including native species. Grass carp are an option only in areas where impact to all of the vegetation is acceptable. The stocking rates for grass carp have not been established. Local and state laws should be checked before release. Some experts do not recommend grass carp for water hyacinth.
There are three insects that have been successfully introduced to control water hyacinth: two water hyacinth weevils (Neochetina bruchi, Neochetina eichhorniae) and the water hyacinth moth (Niphograpta albiguttalis). N. bruchi is native to Argentina, was released in 1974 and is now established in Florida, California, Texas and Louisiana. N. eichhorniae, also native to Argentina, was released in 1972 and is now established throughout the southeastern U. S. where water hyacinth is present. N. albiguttalis was released in 1977 and is now established in Florida, Mississippi and Louisiana. All of these species have been successful at reducing water hyacinth populations to some degree. N. eichhorniae is considered to be the most successful of the three introductions. Other control measures are usually necessary.
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