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How to Control Alligator Weed

Non-Native

alligator weed covering area

Alternanthera philoxeroides

More Info & Photos of Alligator Weed

Non-Herbicide Management Options

1. Physical Management Options

Alligator weed can be cut or grazed, but it is difficult to control physically because it will propagate from stem fragments or the roots.

2. Biological Management Options

Alligator weed flea beetles have demonstrated effective control, but are not commercially available. Depending on location and environmental conditions, populations may be found in the wild. Even if naturally present, biological control is often best used with other control options as part of an integrated pest management strategy.

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 Alligator weed include:

  • Bispyribac (Rated: Exellent)
  • Flumioxazin (Rated: Good)
  • Glyphosate (Rated: Good)
  • Imazamox (Rated: Good)
  • Imazapyr (Rated: Excellent)
  • Triclopyr (Rated: Excellent)
  • Florpyrauxifen-benzyl

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

1) Bispyribac

Bispyribac-sodium comes in water soluble powder form in packets. Each packet should be mixed with water first and then sprayed or injected. It is a selective, 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. A surfactant (substance that can reduce the surface tension) will be needed if herbicide is applied to foliage of floating or emergent plants.

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

  • Tradewind

2) 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:

  • Clipper

3) Glyphosate

Liquid glyphosate formulations have been effective on alligator weed 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:

  • Rodeo
  • Aquamaster
  • Eraser AQ
  • Touchdown Pro
  • AquaNeat
  • Refuge

4) 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:

  • Clearcast
  • Beyond Herbicide

5) 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:

  • Habitat
  • Arsenal
  • Polaris

6) 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:

  • Renovate
  • Navitrol
  • Ecotriclopyr

7) Florpyrauxifen-benzyl

Florpyrauxifen-benzyl is a 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.

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

  • ProcellaCOR EC

Currently, ProcellaCOR EC is only available through SePRO Stewards of Water who are PRO Certified as ProcellaCOR Specialists. 

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. To assist you with these determinations see SRAC #103 Calculating Area and Volume of Ponds and Tanks.

Many aquatically registered herbicides have water use restrictions (See General Water Use Restrictions).

To see the labels for these products click on the name. Always read and follow all label directions. Check label for specific water use restrictions.

Cultivation Options

This is a non-native plant that should not be grown as it is invasive and illegal to possess or transport this species in Texas. Please report sightings to the Texas Parks and Wildlife Department at (512) 389-4800.

Questions?

If you need assistance, contact the Ag & Natural Resources agent in your county or hire a professional.

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Photo Credits: The majority of the aquatic plant line drawings are the copyright of the University of Florida Center for Aquatic Plants (Gainsville). They are used with permission.

Aquatic plant photographs were provided by David Bayne, Jim Davis, Kelly Duffie, Billy Higginbotham, Michael Masser, John Clayton, Chetta Owens, Diane Smith, Joe Snow, Don Steinbach, Bridget Robinson Lassiter and Peter Woods.

You may use these photos, so long as you give credit to AquaPlant.

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