Homemade Aquatic Weed Control

Aquatic weed control methods vary widely depending on the type of plant causing the problem, and whether the aquatic environment is a farm pond, commercial fish breeding facility, water garden, or a feature of the natural landscape. Some aquatic weed control requires the use of registered pesticides or commercial harvesting machinery not readily available to the average homeowner. Homemade aquatic weed control devices and methods can also be quite effective, particularly in small ponds.

Barley Straw

• According to the Purdue University Department of Botany, the use of barley straw for algae management by a homeowner in a privately owned pond qualifies as a home remedy, and thus does not come under U.S. Environmental Protection Agency regulation as a registered pesticide. Apply 1/2 lb. of barley straw per 10 square feet of surface area, early in the spring. Loosen the bales, then lightly pack the straw into mesh onion bags and float them in the pond. Add aeration to the pond to aid in decomposition. As the barley straw decomposes, it may prevent new algae from growing -- although American university studies have shown that barley straw does not kill algae that is already present.

Fish and Manual Weeding

• Persistent manual weeding is the first home-grown line of defense against aquatic nuisance plants other than algae. Wade in and gently pull aquatic plants out, being sure to get their roots or rhizomes. Ensure that any farm or lawn runoff entering the pond is pre-filtered to remove any excess nutrients that may be encouraging excessive aquatic plant growth.

  Fish eat aquatic plants, and some fish eat more than others. Koi eat a small amount of aquatic plants, but their active swimming and high ammonia output discourage plant growth -- while producing more koi, and economically viable farm or backyard pond output. For true aquatic weed control at home, however, try sterile grass carp. You may require a permit from your state fish and game department to release carp, but the sterilized grass carp will not reproduce, so they present minimal hazard even if they escape into the natural aquatic environment. Grass carp are strict herbivores that will gorge on soft herbaceous aquatic plants -- and can then be eaten themselves, at the dinner table.

Drawdown and Barriers

• A severe aquatic plant weed control problem in a private pond may be handled at home by drawing down the pond and letting the bottom weeds die off. Rake the weeds' roots, rhizomes, and leftover vegetative matter out carefully before refilling the pond. While the pond is drawn down, consider placing a physical barrier, such as a rubber pond liner, over the bottom or a portion of the bottom to preclude weeds from taking hold again. Alternatively, dig the pond out deeper -- most aquatic plants require nearly full sun, and thus thrive in shallower ponds.