Biological Control of Aquatic Plants

many Pond owners desire biological or natural techniques to control unwanted aquatic plants there are a few biological methods that when applied properly can be very effective and environmentally friendly to your pond grass carp or a non-native Plante eating fish that can be stocked in ponds to provide control of some types of aquatic plants grass carp provide excellent control of some plants but when you used improperly they can have negative impacts such as increased algae growth and muddying of water you should first determine if your nuisance plant is a preferred food of grass carp they prefer rooted submerged plants like elodia niad mil foil and various Pawn weeds but they do not prefer algae and rarely eat floating or emerging plants you must also obtain a state permit from the Pennsylvania Fish and Boat Commission to purchase sterile grass carp from an approved Hatchery the fish you buy will be about 10 to 12 in to maximize their chances of survival after stocking they can live for more than 10 years but their effectiveness usually declines after about seven or eight years and new fish must be stocked other fish species including koi common carp and Israeli carp are sometimes marketed for control of aquatic plants and algae but they're usually not effective various Pond additives have recently been developed that may reduce aquatic plant growth through biological processes these products contain bacteria and enzymes that feed on nutrients making them unavailable for plant growth there are currently no permit requirements for the use of these products in Pennsylvania and success has been mixed some products are expensive they may require multiple applications during each year and results may be affected by the water quality conditions in each Pond use of these products seems most effective on ponds with little or no overflow still as these products are further developed they appear to be a promising alternative to the use of harsh chemicals in aquatic PL control a final biological alternative for specific control of filamentous algae is barley straw some Pond owners claim remarkable control with barley straw While others report no effect or even increased algae growth barley straw is a preventative measure that must be done months before the growing season to prevent algae growth approximately 3 to five bales of barley straw should be used per acre of pond area the Bales should be broken apart and submerged in bags cages or other containers that will allow water to move through the straw the containers should be placed where water will move through them such as pond