Northern Watermilfoil


Ecological Importance

Leaves and fruit of northern milfoil are consumed by a variety of waterfowl. Beds of northern milfoil offer shade, shelter and foraging opportunities for fish.


Dense stands of Northern milfoil can inhibit recreational uses like swimming, boating, and fishing.

Plant Description

Northern milfoil has light-colored stems that emerge from root like stalks and rhizomes. Leaves are divided like a feather, with a short stalk and about 5-12 pairs of thread-like leaflets.

Hints to Identify

Eurasian watermilfoil typically has 12 to 21 pairs of leaflets. The native northern watermilfoil, with which it is often confused, usually has 5 to 9 pairs.

Common Application Questions

Q. When is the best time to treat?

A. Once water temperatures are around sixty degrees or warmer and the plants are viable.

Q. How often do I need to treat?

A. On average, two applications per season. Your treatment site results will establish their own history and hence the future predictability. Keeping good records of your application will expedite any tailoring that need to be done. Remember, we are here help!

Q. How long before I see results?

A. Generally within ten to sixteen days things will be cleared up.


Homeowner Treatment Options
2,4 D Amine
Aquathol K
Aquathol Super K
Hydrothol Granular
Renovate Max G
Renovate OTF
Sonar AS
Sonar RTU
*Aquatic Biologists recommends implementing preventative management techniques and physical removal prior to, or in conjunction with treatment.