Careful pond site selection and proper pond construction practices are the first steps in preventing aquatic weed problems. Edges of new and existing ponds should be deepened so shallow water areas are minimized. The USDA Soil Conser-vation Service provides technical assistance for pond construction and renovation. Farm ponds are commonly fertilized to increase the fish production capacity of the pond. Fertilization is also an effective and economical way to prevent the growth of many aqua-tic weeds.
Fertilization stimulates the growth of plankton algae.
This algal growth is known as a bloom. The bloom blocks sunlight from reaching the pond bottom which limits the establishment of rooted aquatic weeds. The key to successful control of aquatic weeds with fertilization is to establish and maintain a bloom before rooted weeds begin spring growth. Decreasing the pond water level exposes shallow areas to freezing temperatures and drying and can effectively limit certain types of submersed weeds. For a drawdown to be effective, the water level should be lowered in the late fall and not allowed to refill until the early spring.