Aquatic herbicides eliminate vegetation in ponds and lakes through different means of destroying the plants or hindering their growth and reproduction. It is important to choose the right type of herbicide to tackle whatever overgrowth your pond is experiencing. Learn how common aquatic herbicides work below to help guide your decision.
How Contact Herbicides Work
Contact herbicides only destroy plant cells in areas with which they come into direct contact, such as leaves and stems. These compounds cannot travel through target plants’ vascular systems, so they often require repeat applications to eradicate weeds fully. Additionally, they do not prevent new growth and are best applied when weeds are actively growing in the spring and summer.
Diquat Herbicides
Diquat aquatic herbicides, like Ultra PondWeed Defense, work by disrupting photosynthesis on contact. Diquat is an excellent choice for controlling invasive, fast-growing weeds like duckweed, curly-leaf pondweed, and watermilfoil. It is a non-selective herbicide, so ensure it doesn’t contact pond plants you wish to keep.
Flumioxazin Herbicides
Flumioxazin contact herbicides inhibit chlorophyll synthesis in plants, which starves them of their food source. KnockDown Defense is a non-selective (i.e., knockdown) flumioxazin herbicide that controls a wide range of aquatic weeds and algae.
Fluridone Herbicides
Fluridone is a selective contact herbicide that prevents carotenoid production, causing a chain of devastating effects on targeted plants. Without carotenoids, chlorophyll is destroyed along with key pillars of the photosynthesis process, leaving behind bleached plants that are susceptible to overheating. WipeOut PondWeed Defense is a fluridone aquatic herbicide that is effective against many floating and submerged weeds.
Endothall Herbicides
Endothall affects different plants in various ways, including inhibiting mRNA and lipid synthesis, destroying cell membranes, and preventing germination. EasyKlear Defense endothall-based herbicide and algaecide is highly effective against submerged weeds and bottom-growing algae.
How Systemic Herbicides Work
Systemic herbicides provide longer-lasting control of nuisance vegetation than contact herbicides. These compounds translocate through plants via their vascular systems, obliterating them from shoots to roots.
Glyphosate Herbicides
Glyphosate is the most widely used systemic herbicide that works by preventing amino acid production in plants. A powerful aquatic glyphosate herbicide, Shoreline Defense Emergent Weed Control quickly decimates stubborn pond grasses like cattails and phragmites.
Learn More About Aquatic Herbicides
Are you curious about the science behind the herbicides you use in your pond? Dig deeper into the studies in this fact sheet published by the Southern Regional Aquaculture Center. Do you need advice on which herbicide you should use to treat persistent weeds? Contact us online or call 866-POND-HELP for personalized advice.
Read more about aquatic herbicides in these related articles:
Only Use EPA-Registered Herbicides & Algaecides
Controlling Pond Weeds That Return After Treatment
Continuing Herbicides in Winter
How to Kill Lily Pads Without Harming Fish
Last Updated: March 20, 2025