Herbicides are just one method of managing aquatic weeds. There are also: 1) preventive methods such as proper pond site selection and construction, fertilization andperiodic draw-downs; 2) biological methods such as grass carp (Ctenopharyngodon idella); and 3) mechanical methods such as cutting, seining and raking. Using a combination of methods is the most effective method of managing aquatic weeds.
Aquatic herbicides are chemicals used to kill aquatic plants or severely interrupt their growth. About 200 herbicides are registered by the EPA for use in the United States, but only six are labeled for use in aquaculture sites. It is important that aquaculturists use these registered herbicides in a safe and effective manner.
Aquatic weeds are a common problem in recreational ponds. This document discusses aquatic weeds and ways of controling them.
Basic methods used to control weeds include preventive, mechanical, biological and chemical techniques. Determining which of these techniques to use involves consideration of the target weed species, fish production objectives for the pond, secondary water uses and the cost of treatment options.
When ponds are fertilized, nutrients stimulate the growth of microscopic plants in the water (phytoplankton). Phytoplankton is food for other organisms (zooplankton and larger animals) that are eaten by fish. Abundant growth of these microscopic plants gives water a turbid, greenish color (called a “bloom”) that can prevent light from reaching the pond bottom and reduce the growth of rooted aquatic weeds.
Lakes and ponds can develop dense stands of aquatic vegetation that interfere with intended uses and destroy the natural beauty of the water. Most aquatic weed problems result from poor planning and poor management. Manipulating factors such as water, light and nutrients can help prevent weed growth.