How to Kill Lily Pads
Lily pads are a part of the natural life support system of a pond. Lily pads help oxygenate the water and provide cover for fish and other aquatic life. They can also support amphibian life such as frogs. The problem arises when the lily pads begin to overtake the surface of the pond. This prevents light from getting to the water. While a few lily pads are recommended, too many can use up the oxygen needed for other life in the pond.
Estimate the coverage of the lily pads over the entire pond. Coverage of 30 percent to 50 percent is considered normal for a healthy pond. If you can see at least half of the surface of the pond, you have a healthy ratio. If you have a dense coverage area in one section, treat that section before proceeding with the remaining area; this could eliminate the need for further treatment.
Use a rake to pull out lily pads within reach of the shore. Rake the lily pads to the shore and scoop them out of the water. This will eliminate a good number without the need for chemicals, which can harm fish or wildlife.
Use the aquatic glyphosate product. This chemical is similar to the weed killer Roundup. Spray the lily pads as directed by the manufacturer. Concentrate on small areas of the pond. This decreases the chance of decomposing plants feeding gasses to the remaining plants; this also keeps the dead plants from crowding out light and oxygen. Rake off any dead or dying vegetation.
Wait one week before treating another area of the pond. Repeat step 2 on the next largest group of lily pads. Continue this process until the lily pads have been reduced so that they cover one-third of the pond.
Introduce young grass carp into the pond. Use three fish per acre. Younger carp eat more vegetation than older carp. Introduce a young grass carp per acre per year to offset the aging community until the carp begin to populate on their own.