Stem

Aquatic weed up to 12 ft. long, submersed, branched near water surface, growing points often reddish; breaks into fragments easily

Leaves

Whorled with 4 leaves per node; leaves are green to brown, less than 1.25 in. long and pinnately-divided with more than 14 pairs of narrow, opposite lobes, less than 0.4 in. long

Flower

Pinkish and small, each with a small, bract-like leaf
Occur in clusters on small, pencil-like stalks that emerge from water, 1-3 in. long; stem often bends to become parallel with the water surface after flowering

Root

Creeping rhizomes

Other

Most common in still or slow-moving water but can sometimes be found in fast-moving rivers, streams and irrigation ditches; known to occur in Carson City, Douglas and Washoe counties
Perennial; reproduces by rhizomes, stem fragments and seed

Control

Mechanical removal can be effective but must be done repeatedly; escaped stem fragments can form new plants; draining then allowing an empty water-body to freeze can be effective
Aquatic herbicides such as 2,4-D, copper complexes, diquat, endothall, fluridone, and triclopyr are effective; large infestations should be treated a portion at a time to prevent low oxygen levels as plants decompose

Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Nevada Noxious Weed Field Guide – Eurasian watermilfoil, Extension, University of Nevada, Reno, Field Guide

Learn more about the author(s)

Heidi Kratsch

Also of Interest:


Nevada Noxious Weed Field Guide – Curlyleaf pondweed Curlyleaf pondweed is a noxious weed that has been identified by the state of Nevada to be harmful to agriculture, the general public, or the environment. Learn more about this weed. Blecker, L., Creech, E., Dick, J., Gephart, S., Hefner, M., Kratsch, H., Moe, A., Schultz, B. 2020, Extension, University of Nevada, Reno, Field Guide

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Nevada Noxious Weed Field Guide – Eurasian watermilfoil