LUMBERTON — Around this time and, unfortunately, late in the season, I start receiving phone calls about how to identify and get rid of aquatic weeds.

Some of the most common weeds I have seen growing in ponds around the county are duckweed, proliferating spikerush, bladderwort species, pondweed species, and several algae species. Plants are needed in aquatic habitats to help provide oxygen to other aquatic species, but they grow so quickly they can negatively affect the pond. Aquatic weeds can interfere with swimming, fishing, or other recreational activities if not controlled.

Aquatic weeds can be divided into six groups: algae, free floating, floating rooted, submersed, shoreline and grasses, sedges, and rushes. Properly identifying the weeds is the first step in controlling the weeds. Control methods are usually species specific, so knowing what type of weed is critical. Biological, mechanical, and chemical control are ways to reduce and/or control aquatic weed growth.

Biological control of aquatic weeds usually refers to the stocking of grass carp. Triploid grass carp are sterile fish that cannot reproduce and feed on plants. Grass carp primarily feed on submersed plants. The amount of grass carp to stock will depend on the size of the pond and the extent of the weeds. The general rule of thumb is 10-15 grass carp per acre and bigger than 10 inches in size to prevent predation by larger fish.

Mechanical control involves harvesting by hand or machine. Mechanical control has both advantages and disadvantages. The advantages are that decaying weeds can be removed and it eliminates the need for herbicides, which can have water-use restrictions. The disadvantages are that weeds can be time consuming to remove and vegetation can be dispersed elsewhere in the pond.

Chemical control involves the use of herbicides to remove unwanted aquatic weeds. There are many different herbicides labeled for aquatic use. ALWAYS read and follow the directions, taking special notice for water-use restrictions.

There is a publication with information on the effectiveness of grass carp and herbicides on aquatic weeds. If you would like a copy, or need help identifying aquatic weeds or an appropriate herbicide, please contact Taylor Chavis, livestock agent with North Carolina Cooperative Extension, Robeson County Center, at 910-671-3276, by [email protected], or visit our website at http://robeson.ces.ncsu.edu/.

Taylor Chavis is the livestock agent at the Robeson County Cooperative Extension. She can be reached at 910-671-3276 or [email protected].