Efficacy of Herbicide Active Ingredients Against Aquatic Weeds

Hydrilla in a lake

Weed control is often a critical component of aquatic vegetation management in Florida waters. While physical, mechanical, and biological controls are utilized where they are feasible, herbicides are the primary tool used to control many troublesome species. This document answers some common questions and provides efficacy information for all herbicide active ingredients labeled for aquatic use in Florida. Written by S. F. Enloe, M. D. Netherland, W. Haller, and K. Langeland, and published by the UF/IFAS Agronomy Department, revised February 2018.

East Indian Hygrophila: Hygrophila polysperma (Roxb.) T. Anderson

Emergent growth of East Indian hygrophila.

East Indian hygrophila is a submersed aquatic weed that has invaded a number of aquatic systems in the southeastern United States. It is a federally listed noxious weed and a Florida Class II prohibited plant. Established populations of East Indian hygrophila interfere with human uses of bodies of water and disrupt ecosystems by forming dense, impenetrable monocultures that clog the water column, restrict water flow, and create poor habitat for aquatic fauna. This 5-page fact sheet provides an overview of the plant and discusses its habitat and control. Written by Lyn A. Gettys and Stephen F. Enloe, and published by the UF Agronomy Department, December 2016.

Waterhyacinth: Florida's Worst Floating Weed

Figure 1.  Inflorescence of waterhyacinth Credit: Lyn Gettys, UF/IFASWaterhyacinth is one of the world’s worst aquatic weeds and is Florida’s most intensively managed floating plant. Dense mats formed by this species interfere with human uses of water bodies and disrupt ecosystems by preventing penetration of light and oxygen into the water column. This attractive, free-floating aquatic plant grows throughout the year in southern Florida but often dies back during the winter in the northern parts of the state. Waterhyacinth is cultivated as a water garden and pond plant, but cultivation, sale, and possession of this noxious weed is prohibited in Florida. This 5-page fact sheet was written by Lyn A. Gettys, and published by the UF Department of Agronomy, September 2014.

Rotala: A New Canal Invader in Southern Florida

Figure 1.  Rotala infesting a flood control canal in Naples, Florida  Rotala is a relative newcomer to Florida. Since it was first found in Coral Springs in 1996, it has established large, but mostly isolated, populations throughout the southern regions of Florida. It is especially problematic in Lee and Collier Counties and along the west coast. Extremely dense submersed populations and large thick mats dominate the surface of the water, greatly reducing ecosystem services, because oxygen level and light penetration are hampered. Because the rapid and vigorous growth of rotala inhibits water flow, the ability of infested canals to function properly in flood control systems is greatly hindered. Management of this aquatic weed is a major concern for resource managers. This 4-page fact sheet was written by Lyn A. Gettys and Carl J. Della Torre II, and published by the UF Department of Agronomy, April 2014.

Grass Carp: A Fish for Biological Management of Hydrilla and Other Aquatic Weeds in Florida (BUL867/FA043)

Figure 2.  A mature grass carp, highly effective in controlling Hydrilla and many other noxious aquatic weeds.Abundant growth of aquatic plants causes serious problems in ponds, lakes, rivers, and irrigation and drainage throughout Florida. In some situations, native aquatic plants become weeds, but most often exotic plants introduced from areas outside the state flourish under the favorable growing conditions found in Florida. Long-term economical solutions to Florida’s aquatic weed problems have been elusive and there is a need for control techniques to alleviate aquatic weed problems. This 6-page fact sheet provides information on a biological method, the grass carp, for management of some of Florida’s aquatic weed problems. Written by David L. Sutton and Vernon V. Vandiver, Jr., and published by the UF Department of Fisheries and Aquatic Sciences, November 2013.

Hydrilla Management in Florida Lakes (SSAGR361/AG370)

Hydrilla infestation on an 8–10 foot deep Lake Tohopekaliga in Central Florida.Hydrilla is the most aggressive invasive plant in Florida waters. It can provide some benefits to fish and wildlife at low levels of coverage, but it also can have major detrimental impacts to water uses, causing substantial economic and environmental hardships. This 6-page fact sheet was written by Stacia A. Hetrick and Ken A. Langeland, and published by the UF Department of Agronomy, March 2012.

Aquatic Weeds: Crested Floating Heart (Nymphoides cristata) (SSAGR344/AG354)

Crested floating heart is a native of Asia, but was introduced to North America through the aquatic plant nursery trade and marketed as ‘snowflake.’ In the United States, crested floating heart escaped from cultivation and became established in Florida water bodies. Learn how to identify and manage this aquatic weed in this 5-page fact sheet written by Leif N. Willey and Kenneth A. Langeland and published by the UF Department of Agronomy, April 2011.

ABE383/AE432 BMP: Ribbon Barriers

Figure 1. Example of Ribbon Barrier
ABE-383, a 2-page illustrated fact sheet by Kati W. Migliaccio, Brian Boman, Jemy Hinton, and Kevin Hancock, addresses a specific set of Best Management Practices that can be described as ribbon barriers. Includes references. Published by the UF Department of Agricultural and Biological Engineering, October 2008.