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second edition • Nebraska Pond Management • 63 Submersed plants are usually rooted to the bottom and grow upward to the surface of the pond. Their blossoms and seed pods extend above the water surface. The plant usually consists of a long flexible stem, with clumps of narrow leaves along it. Surface leaves of some species look quite different than lower leaves. These plants can form thick beds that interfere with fishing, swimming, and boating. Examples are pondweeds (Potamogeton spp.), coontail, water milfoil, and water lily. Depending on water clarity, some of these plants can grow in water depths exceeding 10 feet. Emergent plants are rigid, rooted to the pond bottom and extend upwards out of the water. They usually occur along the shoreline and grow in water depths less than 3 feet. Many emergents reproduce by seeds and rhizomes. Cattails are probably the most familiar emergent plants. Although they provide excellent shoreline protection and sediment entrapment, they are notorious for rapidly filling-in shallow areas of ponds. This can result in elimination of other desirable aquatic plants and limit shoreline activities such as fishing, wading, and boating. Bulrushes, sedges, smartweeds, arrowheads, and pickerelweeds are other common emergent plants. Trees, such as willow and cottonwood, are also included in this group. Purple loosestrife is an exotic emergent that can take over extensive shoreline areas and entire wetlands. Controlling Aquatic Vegetation Aquatic vegetation can provide a variety of benefits. Although a particular level of abundance may be too much for one pond owner, it may be just right for another. As long as aquatic vegetation, primarily submersed type, isn't negatively affecting fish populations, especially largemouth bass, it can be allowed to cover 40% or more of the pond surface, depending on fish management goals. Once it gets above 40%, some may have to be removed to create open- water areas. Control for each vegetation type can involve one or more of the following techniques. Prevention Prevention is the best control. Follow depth and slope guidelines presented earlier to reduce the amount of shallow-water areas where plants can grow. Utilize wise land use practices that prevent soil erosion and keep nutrients on the land and out of the water. Prevent animal wastes from entering — either construct a sewage lagoon to catch feedlot and barnyard runoff or divert it around the pond through a grass-lined ditch when permissible. Physical or Mechanical Removal The physical removal of aquatic vegetation from a pond is a valuable control technique. This is done by cutting or uprooting rooted plants and removing them from the pond. Floating plants can be collected with seines and removed, especially on windy days when the plants are concentrated along one shoreline. Plants can be removed by hand with simple tools or with special cutting machines. In shallow shoreline areas, plants can be pulled by hand, cut with a sickle, dug out with a shovel, or removed with a rake or a chain pulled through the pond behind a tractor or ATV. Undesirable plants should be controlled when they first show up, before they get a chance to spread extensively. Remove as much of the plant's roots as possible, when applicable. For larger ponds or deep water, commercial power cutters are a more sensible option. The most important part of mechanical control is to remove the cut plants from the pond. Many aquatic plants can grow from plant fragments, so cutting one stem in half doubles your problem. Fragments that don't grow will decompose and release nutrients that stimulate other plants to grow. The decomposition process also uses up oxygen and can cause fish kills. Removing the vegetation from the pond removes all the nutrients stored in them, reducing the Depending on fish management goals, aquatic vegetation can cover 40% or more of a pond's surface.