Problem Wetland Plants


Undesirable Plant Species

Some wetland plants can become undesirable because they cause problems under certain conditions. However, these same plants can prove beneficial in other circumstances. For example, marsh smartweed is a perennial that produces very little seed and can crowd out other more beneficial plants. Yet it provides an excellent environment for invertebrates, which are an important food source for many wetland wildlife species.

In some cases, plants are listed as undesirable because they are very aggressive and will crowd out other plants, resulting in a monotypic stand (only one kind of plant), which is less desirable than a mixture of plants.

Problem Wetland Plants and Their Control


  • Flood in summer with shallow water when plants are less than 12 inches.
  • Mow to 4 inches when plant begins to put on seed.
  • Shallow disking any plant height.
  • Apply 2-4D at ¼ to ½ pound per acre.

Willow, cottonwood, maple, green ash:

  • Practice heavy/deep disking in summer.
  • Use double-cross disking in growing season.
  • Mow in the fall, followed by flooding next growing season.

Marshmallow and buttonbush:

  • Practice heavy offset disking in summer; repeat in 2-4 weeks.
  • Spray Rodeo in early growing season at rate of 1 pint to 1 quart per acre.
  • Weed wipe with 50 percent Rodeo.

Cattails and river bulrush:

  • Burn twice in summer.
  • Flood 3 feet deep from fall through next growing season.
  • Spray Rodeo, 1 quart per acre.

American lotus:

  • De-water in February or at any point before new leaves reach water surface.
  • Use shallow disking after de-watering (optional).
  • Spray Rodeo, 1 quart per acre.

Marsh smartweed (P. coccirzeum):

  • Use heavy/deep disking in summer followed by herbicide treatment of regrowth.
  • Apply Rodeo at 1 quart per acre.

Purple loosestrife:

  • Apply Rodeo during full bloom (July–August) in a 1- to 2-percent solution with a surfactant (wetting agent).
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