Green Algae Control Lake Management

Submerged Aquatic Plants

    This section of Aquatic vegetation covers a wide variety of diverse and unique plants. Some of which will wildly vary from one another while others are very difficult to distinguish from others. Some are very aggressive and others pose little to no threat. The trick to managing submerged vegetation is first knowing the species, associated threat and the management goals you wish to achieve.
    Eliminating all vegetation is often unadvisable in ponds used for sport fishing. The vegetation's value as fish structure and habitat should always be calculated before deciding to eliminate it all together. As stated above you must keep your management goals in view and know how each vegetation type can contribute to meeting your goals but you must also know what risks each vegetation may pose.
    As with all vegetation, proper identification is of the utmost importance. Unfortunately this group of vegetation is often the most difficult to ID. The picture below shows some of the subtleties between hydrilla and three plants that closely resemble it. If you have any questions at all about whether or not you have properly identified your vegetation please have it confirmed by a professional before moving forward with a treatment regiment that may not be successful.
Submerged aquatic plants
     The University of Florida, Center for Aquatic and Invasive Species, has a great website for the identification and general information on many types of aquatic plants.

Common Submerged Aquatic Plants

Coontail, Bushy Pondweed and Sago Pondweed are the most commonly found submerged plants throughout Texas and particularly on the Gulf Coast. Bladderwort and Cabomba are more often found in the eastern portion of the state while Variable Leaf Water Milfoil and Curly Leaf Pondweed are more frequent in the Hill Country. Keep in mind that none of this is written in stone so don't rule out any plants based on this generalization, this is only intended as a starting point.

Hyrdilla is by far the most recognized name in aquatic plants. While there are Hydrilla infestations spread far and wide over the state its reputation often exceeds it as it's often falsely named the culprit
Bushypondweed
Coontail
Hydrilla
Sago Pondweed

Control of Submerged Plants

The treatment of such plants can be broken down into a few distinct categories. Contact Herbicides, Systemic Herbicides, and Mechanical and Biological methods.

Contact Herbicides are aptly named as they require direct contact with target species for a set amount of time. These products can be used at anytime of the year as long as the plants are present and often offer quick results. Some Contact Herbicides will show results in as little as 3-5 days with complete die off within 2 weeks. There are times when Contact Herbicides are the best option but generally speaking they don't control the roots systems and can allow regrowth within 2 months time. With the prolonged growing season that is dominate over most of Texas this can make the cost of multiple applications a big limitation.

Systemic Herbicides are often a better choice. Systemic means that the entire plant is controlled, all the way down to and including the roots. Because of this systemic action these products are usually slow to show results, however the results often last an entire season. Another limitation of Systemic products is that the plants MUST be actively growing in order to absorb the chemical and have it be effective. This gives a definite time window for successful applications of Systemic Herbicides.

Mechanical Controls such as raking, dragging and other means of manually removing vegetation offer instant results. The drawback to this method is the extreme labor involved and short lived results, this can be accurately compared to mowing your yard. Additionally some species are capable of spreading by fragmentation. This means that should you break the plant into multiple pieces each piece can form a new plant.
Biological methods include, Grass Carp, Tilapia and other natural methods of vegetation consumption. Grass Carp can be effective at controlling certain types of plants but they are very picky eaters and have a set preference of desired species. Should you have one of highly preferred species Grass Carp should be a consideration. Tilapia will also consume vegetation and are less picky eaters than the Carp. Tilapia also come with their own set of limitations, being a tropical fish they are susceptible to winter kills with water temperatures in the low 50s. Tilapia are very prolific and can spawn every 7-14 days, the bulk of thier young survive as they are what's called mouth brooders. Tilapia will hold their young in their mouths to keep them safe from predators, this can lead to population explosions and can cause your water to become muddy. These fish will also compete with your natural forage species and potentially reduce their numbers, having a negative effect on your fishery.
A successful management plan will often include the use of Herbicides, some form of Biological means and a preventative maintenance regiment. Contact your Lake Manager for more information on building the appropriate Management Plan.

Aquatic Plants Factsheets