Options for Controlling Aquatic Plants

In common parlance the terms aquatic plant control and aquatic plant management are often used interchangeably. However, when used in a technical way, controls are the techniques or method used to reduce plant biomass. Management includes the goals and objectives. Control efforts can be used for management objectives ranging from containing a plant species so that it cannot spread (containment or maintence control), to temporary or incomplete eradication, to complete and permanent removal of the plant species, including any reproductive structures in the water body. Management includes strategies beyond control efforts such as education to prevent the spread or reintroduction of an invasive plant, like hydrilla. A management plan (Cayuga Inlet's Management Plan) takes into account many factors such as the uses (current and future) of the water body, the priorities of stakeholders, and the resources available (money, expertise, regulations, etc.).  Resource: A Manager's Definition of Aquatic Plant Control 

Controls

Managing for invasive species is site-specific and some controls only work in certain situations. Often, a combination of controls are used to fight the infestation. Different controls may work better at different points in time or in different situations. Control options fall into four general categories. 

The 4 Main Control Mechanisms:

• Biological: reduce the growth of the plants by introducing predator species such as fish or insects
• Chemical: applying herbicides that will kill or stunt the growth of the weeds
• Mechanical: removing the plant (and/or roots) by cutting/dredging, harvesting, or rotovating
• Physical: disturbing the plants ability to grow by altering the light, soil, or water conditions

Prevention is key! 

Control alone cannot eliminate the threat of hydrilla. Control practices are used for eliminating the existing populations. Prevention is necessary to avoid future invasions and to stop the spread of hydrilla to new locations until eradication is achieved. Prevention is the first line of defense because if the plant isn't in a waterbody, there is no need to develop control methods. Given that small fragments of hydrilla can "hitchhike" on boats and other equipment to new locations and re-root, prevention is very important. 

Find out more on how you can help prevent the spread of hydrilla! 

Management Plans

Some management plans have been aimed at complete eradication of hydrilla and have succeeded in this effort (Successful Eradication in the US), while others are used to contain the existing population. Areas with well-established infestations have lost the ability to completely get rid of the weeds (as seen on the Invasion Curve) and use control methods (often mechanical/physical every year and chemicals every few years) in hopes to regain some form of use during the boating/recreation season. 

Florida spends millions of dollars a year to clear boat channels through dense hydrilla infestations. Larger view of Image 

Credit: SW FL Water Management District

Last Updated: June 12, 2013