Noxious Weed Control

Ponds are often built to supplement farm income via fish production, for personal enjoyment, or for stormwater management. Soon after the pond is constructed, unforeseen problems often arise. One major problem that occurs is that the pond becomes clogged with aquatic plants. The level at which an aquatic plant becomes a weed problem depends on the pond’s intended use. A farm pond used primarily for weekend fishing can tolerate considerably more vegetation than a pond constructed specifically for fish production and/or irrigation. Shoreline grasses can help stabilize and prevent bank erosion, but out of control grasses may encroach into the water, where they restrict access and usability.

Prevention is the best technique for reducing takeover by aquatic weeds. It’s easier and more economical to prevent weed problems than it is to cure them.

Proper care can help minimize erosion and nutrient enrichment from the runoff of silt and inorganic and organic fertilizers that decrease the lifespan of the pond and limit its usefulness. Whether you fertilize your pond for fish production or avoid intentional nutrient enrichment, septic tanks, gardens, roadways, or other sources of runoff  from parking lots and roadways may contribute heavy metals, oils, and pesticide contaminants.

There are many ways to care for a lake or pond and depending on your circumstances controlling Noxious weeds is best determined by talking to one of our lake and waterway management technicians and allowing them to inspect and advise on your best course of action. Some cases, adding certain fish to your pond, lake or waterway may be ideal while in other situations adding certain fertilizers, harvesting the weeds mechanically or spraying them with herbicides may be best. No matter the problem, there are solutions that will solve the issue and ensure your long term goals and beauty of your waterway, lake or pond system.

Waterlettuce(Pistia stratiotes) Description: Resembles a head of lettuce. Grows in a rosette with spongy, dense hairy leaves 6-8 inches in diameter. Daughter plants are the major means of reproduction.Control: Biological: waterlettuce weevil. Herbicides: diquat, endothall liquid.
Waterlettuce (Pistia statiotes) Emersed Plants Pickerelweed(Pontederia lanceolata)Description: An erect plant with lance-shaped leaves up to 10 inches long. Each stem has violet-blue flowers at the top. Reproduction occurs by seed and creeping rootstalks.Control: Herbicides: triclopyr, partial control with 2,4-D and glyphosate.
Pickerelweed (Pontederia lanceolata) Alligatorweed (Alternanthera philoxeroides)Description: Hollow-stemmed perennial capable of forming dense mats. Leaves are opposite between 2 and 4 inches long, and football-shaped. Stems have a solitary white flower head at the tip. Reproduction by fragmentation.Control: Biological: alligatorweed flea beetles and thrips. Herbicides: triclopyr, partial control with 2,4-D and glyphosate.

Alligatorweed (Alternanthera philoxeroides)Cattail(Typha species)Description: Erect perennials (up to 9 feet) that can reproduce by seed or creeping rootstalk. Grass-like leaves are flat and smooth to the touch. Flowers look like a “cat’s tail” and can be found in a tightly packed spike usually 6-8 inches long.Control: Herbicides: diquat, glyphosate, fluridone.

Cattail (Typha species) Pennywort (Hydrocotyle umbellata) Description: Dark green, shiny rounded leaves which are centrally attached to a long stalk. Leaves may lie flat on the water surface or be erect. Pennywort reproduces by seed and creeping stems.Control: Herbicides: diquat, 2,4-D, glyphosate, triclopyr.
Pennywort (Hydrocotyle umbellata)Smartweed(Polygonum species) Description: Leaves are alternate, lance-shaped, and attached to swollen joints on the stem. The flower stalk consists of many small pinkish white flowers in a single spike. Smartweed spreads by seed, and may form large floating mats.Control: Herbicides: triclopyr, partial control with glyphosate (species dependent) and 2,4-D.
Smartweed (Polygonum species) White water-lily (Nymphaea odorata) Description: Leaves are flat, rounded, and attached at the center to the stalk. Leaves are often 10 inches in diameter and split to the center on one side. The flower is sweet-scented, white and showy. Reproduction is by seed and branching stems.Control: Herbicides: fluridone, 2,4-D liquid and granular, triclopyr, glyphosate.
White water-lily (Nymphaea odorata)Spatterdock(Nuphar luteum)Archival copy: for current recommendations see or your local extension office. Large heart-shaped leaves arising from a stalk attached to a thick creeping root system. The flower is yellow and about one inch in diameter. Reproduction is by seed and new sprouts.Control: Herbicides: glyphosate, fluridone.
Spatterdock (Nuphar luteum)Submerged Plants Coontail (Ceratophyllum demersum)Description: Leaves grow in a whorl, are finely dissected, and have teeth on one side of the leaf margin. Leaves are 1/2-1 inch in length and crowded towards the stem tip giving the appearance of a raccoon’s tail. Coontail is rootless and floats near the surface in the warmer months. Reproduction is by seed and fragmentation.Control: Biological: grass carp. Herbicides: diquat, endothall liquid and granular, fluridone, 2,4-D granular.
Coontail (Ceratophyllum demersum)Hydrilla(Hydrilla verticillata)Description: Long stemmed, branching plant that is rooted to the bottom and often forms large surface mats. Leaves grow in a whorl with toothed margins that feel rough. Hydrilla can spread by plant fragments, underground stems, seed, leaf buds, or buds located on the underground stems.Control: Biological: grass carp. Herbicides: copper, diquat, endothall (liquid and granular), fluridone.
Hydrilla (Hydrilla verticillata)Bladderwort(Utricularia species)Description: A submersed, free floating plant, having a variety of growth forms. Although leaf shapes and flowers differ, all species bear small urn like bladders which are used to trap small aquatic animals. Reproduction is by seed and fragmentation.Control: Biological: grass carp. Herbicides: diquat, fluridone, 2,4-D granular.
Bladderwort (Utricularia species) Southern naiad (Najas guadalupensis) Description: Bottom-rooted, slender-leaved, dark green to greenish purple plant with branching stems. Leaves are less than 1 inch in length and narrow. Reproduction is by seed and fragmentation.Control: Biological: grass carp. Herbicides: diquat, endothall liquid and granular, fluridone, 2,4-D granular.
Southern naiad (Najas guadalupensis)Fanwort(Cabomba caroliniana)Description: Leaves of fanwort are finely dissected and fan-shaped. Leaves are opposite and generally no more than 1-1 1/2 inches wide. The flower is white or cream colored, about 1/2 inch in diameter and blooms above the water surface. Reproduction is by seed and fragmentation.Control: Biological: grass carp. Herbicides: diquat, fluridone, 2,4-D granular.
Fanwort (Cabomba caroliniana)Pondweed(Potamogeton species)Description: Several species of pondweed are found in Florida; Illinois pondweed (P. illinoensis) is most frequently encountered. It has both floating and submersed leaf forms. The football-shaped floating leaves are not always present, but are easily distinguishable from the lance-shaped submersed leaves. The flowers are clustered together on a spike 1-2 inches long located just above the water surface at the stem tip. Reproduction is by seed and from underground stems.Control: Biological: grass carp. Herbicides: diquat, endothall (Hydrothal) liquid and granular, fluridone, 2,4-D granular.

Grasses and Sedges Torpedograss (Panicum repens)Description: Narrow leaved (less than 1/4-inch wide), with stems often several feet in length. Torpedograss creeps horizontally by underground.

Pondweed (Potamogeton species) stems and forms large floating mats. Reproduction is by seed and creeping stems.Control: Biological: partial control with grass carp. Herbicides: partial control with glyphosate, fluridone.
Torpedograss (Panicum repens)Maidencane(Panicum hemitomon)Description: Maidencane leaves usually grow at 90o angles from the stem and generally 1/2-inch in width. An extensive creeping root system allows maidencane to form dense floating mats with stems often several feet in length. Reproduction is by seed and creeping root stalk.Control: Biological: partial control with grass carp. Herbicides: partial control with glyphosate.
Maidencane (Panicum hemitomon)Paragrass(Brachiaria purpurascens)Description: Paragrass often forms stems several yards in length which often fall on the ground. Paragrass can be easily identified by the dense hairs located at the stem joints. Dense floating mats often form. Reproduction is by seed and stem joints forming roots.Control: Biological: partial control with grass carp. Herbicides: glyphosate, fluridone.
Paragrass (Brachiaria purpurascens)Proliferating spikerush(roadgrass, hairgrass) (Eleocharis baldwinii)Description: Proliferating spikerush has two growth forms. When it occurs on moist soils at the edge of ponds or lakes it is erect and the leafless stems are 1-4 inches tall. When submersed, the stems become long and proliferate throughout the water. Leaves occur only as bladeless sheaths at stem bases.Control: Biological: grass carp. Herbicides: fluridone (repeat applications).
Spikerush (roadgrass, hairgrass) (Eleocharis baldwini) Sedge (Cyperus species) Description: Many sedges are found in Florida and are generally difficult to identify by species. In general, sedges can be identified by the triangular stem and leaf blades, which are generally rough to the touch. Flower stalks arise from the center forming a compact group or headlike cluster of flower spikes. Reproduction is by seed.Control: Herbicides: partial control with glyphosate.
Sedge (Cyperus species)Ditchbank Brush(Myrica cerifera)Description: Shrub or small tree usually 10 feet tall. Leaves are alternate, pale green, and lance-shaped. When crushed, leaves emit a pleasant aroma. Close inspection of the leaves will reveal numerous small dark scales on top and bright orange scales below. Reproduction is by seed.Control: Herbicides: imazapyr,* triclopyr.*Wax myrtle
Wax Myrtle (Myrica cerifera)Willow(Salix species)Description: Fast growing shrub which can become a tree in a short period of time. Leaves are alternate and lance-shaped with finely toothed margins. The fruit capsule contains many small hairy seeds which drift in air currents.Control: Herbicides: partial control with 2,4-D, glyphosate, imazapyr,* triclopyr.Brazilian pepper(Schinus terebinthifolius)Description: An extremely fast growing shrub found predominantly in disturbed areas of south
Willow (Salix species)Florida. This aggressive nonnative species produces large quantities of seeds contained in a red fruit usually about 1/4-inch in diameter. Reproduction is by seed.Control: Herbicides: glyphosate, 2,4-D, imazapyr,* triclopyr.
Brazilian pepper (Schinus terebinthifolius)Water primrose(Ludwigia species)Description: Small shrub attaining height of up to 6 feet with multiple branching stems. Leaves are lance-shaped with small soft hairs on both sides. Flowers are yellow with four symmetrical petals. Reproduction is by seed and underground stems.Control: Herbicides: 2,4-D, imazapyr.
Water primrose (Ludwigia species) Algae Macrophytic algae Description: Macro, meaning large, describes a type of algae that looks more like a submersed plant. Capable of attaining several feet in length, muskgrass (Chara species), is the most common of these algae found in Florida. The algae appear to have a whorl of spined leaves, grey-green in color, resembling the submersed plant coontail. However, algae have no true leaves. When crushed, Chara emits a musky odor.Control: Biological: grass carp. Herbicides: copper, diquat, endothall (Hydrothrol) liquid and granular.
Macrophytic algae  Many species of filamentous algae are frequently a problem in Florida ponds. These threadlike filaments are often called “pond scum” or “pond moss” when they are seen floating on the pond surface. Although many species of filamentous algae can frequently become a problem to pond owners, most species can be controlled in a similar manner. A few species, especially some of the blue-green algae (e.g., Pithophora and Lyngbya), are difficult to control and would require special recommendations from a qualified biologist.Control: Biological: partial control with grass carp. Herbicides: copper, endothall (Hydrothol).
Filamentous algae Planktonic algae Description: Microscopic (planktonic) algae are small plants that cannot be identified without magnification. They occur in all ponds and, after fertilization, give the pond its green color. Most of the microscopic algae are beneficial to ponds, converting nutrients into a source of food in the food chain. There is rarely a need to control microscopic algae; however, when large blooms occur, oxygen depletion, foul odors, off-flavor fish, and even fish kills may occur.Control: Herbicides: copper.