Home Local News How to Control Water Primrose by Mario Villarino

How to Control Water Primrose by Mario Villarino

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A common pond weed invading local ponds in Hopkins County is the water primrose or Ludwigia. This particular weed grows rapidly and can take over ponds starting from the shore. It can also grow in portions of the land near the pond. Its main characteristic is an intense yellow flower blooming this time of the year.

Non-Herbicide Management Options

  1. Physical Management Options

Water Primrose can be cut, and the roots can be dug up. However, physical control is difficult because it can re-establish from seeds or remaining roots.

  1. Biological Management Options

At this time, there are no known biological controls for Water Primrose; although, goats are known to forage on many types of emergent vegetation.

Herbicide Control Options

Always read the product label for directions and precautions, as the label is the law. Click on the name of the product to see the label. Read the label for specific water use restrictions.

The active ingredients that have been successful in treating Water Primrose include:

  1. Flumioxazin (Rated: Good)
  2. Glyphosate (Rated: Excellent)
  3. Imazamox (Rated: Excellent)
  4. Imazapyr (Rated: Excellent)
  5. Triclopyr (Rated: Excellent)
  6. 2,4-D (Rated: Excellent)

These rating are based upon the U.S. Army Corps of Engineers aquatic herbicide trials.

1) Flumioxazin

Flumioxazin is a water dispensable granule that is to be sprayed or injected after mixing. It is a broad spectrum, contact herbicide. Contact herbicides act quickly. Flumioxazin should be applied to actively growing plants and a surfactant (a substance that reduces water tension) will be needed if the herbicide is applied to foliage of floating or emergent plants. Water pH needs to be below 8.5 or flumioxazin will rapidly degrade and lose effectiveness.

Common trade and product names include but are not limited to:

  1. Clipper

2) Glyphosate

Liquid glyphosate formulations have been effective on water primrose above the water line, but ineffective on plants in the water. They are broad spectrum, systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (see the label) will have to be added to the glyphosate solution for good results.

Common trade or product names include but are not limited to:

  1. Rodeo
  2. Aquamaster
  3. Eraser AQ
  4. Touchdown Pro
  5. AquaNeat
  6. Refuge

3) Imazamox

Imazamox is a broad spectrum, systemic herbicide. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (a substance that will release the surface tension) is needed for application.

Common Trade of product names include but are not limited to:

  1. Clearcast

4) Imazapyr

The active ingredient, imazapyr, inhibits the plant enzyme AHAS (acetohydroxyaced synthase). Habitat is a systemic herbicide that is effective on post-emergent floating and emergent aquatic vegetation. Imazapyr is effective at low-volume rates and does not contain heavy metals, organochlorides or phosphates, making it safe to humans and livestock. Habitat requires the use of a spray adjutant when applying on post-emergent vegetation.

Common trade or product names include but are not limited to:

  1. Habitat
  2. Arsenal
  3. Polaris

5) Triclopyr

Liquid triclopyr formulation is a selective broadleaf, systemic herbicide. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides. An aquatically registered surfactant (see the label) will improve the effectiveness of triclopyr.

Common trade or product names include but are not limited to:

  1. Renovate
  2. Navitrol
  3. Ecotrilopyr

6) 2,4-D

2,4-D compounds are systemic herbicides. Systemic herbicides are absorbed and move within the plant to the site of action. Systemic herbicides tend to act more slowly than contact herbicides.

Common trade or product names include but are not limited to:

  1. Navigate
  2. Weedar 64
  3. Restore

Precautions

One danger with any chemical control method is the chance of an oxygen depletion after the treatment caused by the decomposition of the dead plant material. Oxygen depletion can kill fish in the pond. If the pond is heavily infested with weeds, it may be possible (depending on the herbicide chosen) to treat the pond in sections and let each section decompose for about two weeks before treating another section. Aeration, particularly at night, for several days after treatment may help control the oxygen depletion. One common problem in using aquatic herbicides is determining area and/or volume of the pond or area to be treated. Many aquatically registered herbicides have water use restrictions

Cultivation Options

Water Primrose can be propagated by transplanting whole plants into moist soil during the early spring. However, Water Primrose can be an aggressive invader of ponds.

 

 

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