General Information


Pre-Treatment Considerations (All labeled sites):

Permits: Some states may require permits for the application of this product to public waters. Check with your local authorities.

For optimum results:

- Harpoon Aquatic Herbicide should be applied early in the day under bright or sunny conditions when plants are actively growing and water temperatures are at least 60°F (15.5°C).

- Treat when growth first begins to appear or create a nuisance, if possible.

- Apply in a manner that will ensure even distribution of chemical within the treatment area.

- Reduced activity may occur in murky/shaded waters or where silt and/or scale has built up on plant leaf surfaces.

Algae growth around target plants may interfere with uptake of Harpoon Aquatic Herbicide. Pretreat these areas with Cutrine-Plus, EPA Reg. No. 8959-10 or other EPA registered algaecides. Do not exceed 1.0 ppm of total copper when using Harpoon Aquatic Herbicide and Cutrine-Plus.


Note: Always ensure application equipment has been cleaned and is in proper working condition before using Harpoon Aquatic Herbicide. When application has been completed, thoroughly rinse spray tanks, hoses and or pumps with fresh water, disposing of diluted rinsate within the treatment area.


Surface: In shallow areas, such as along shoreline, Harpoon Aquatic Herbicide can be effectively applied using backpack units or portable tank sprayers. Dilute Harpoon Aquatic Herbicide with suffi cient water to evenly and effi ciently treat within the intended treatment area.

Use with Polymer in Application: A sinking agent, approved for water and crops, can be mixed with this product. For each surface acre to be treated, prepare a solution using the correct rate of Harpoon Aquatic Herbicide with water and the sinking agent to achieve a final application mix volume of 100 to 400 gallons. Blend the sinking agent into the herbicide mix following the agent’s directions for use and maintaining continuous agitation while making application. The sinking agent will assist Harpoon Aquatic Herbicide in reaching and adhering to the target plants. Applications are most effective when made on dense areas of growth and when applied moving slowly in opposite direction to the water flow.


Surface: In shallow areas, such as along shorelines, boat-mounted tank-type power sprayers or portable water pumps equipped with appropriate dilution water and chemical intakes with calibration valves can be used to effectively apply Harpoon Aquatic Herbicide through handheld spray wands or adjustable, tapered fi re nozzles. Dilute Harpoon Aquatic Herbicide with suffi cient water to evenly and effi ciently treat within the intended treatment area.

Subsurface Application: Applications in water depths of more than four feet are best made using a weighted trailing hose and applied where growth is most dense, to help assure contact with the foliage. Avoid dragging the hose through the bottom sediment.

Polymer Application: If there is concern about extended contact time with the target plants, a polymer can be blended with Harpoon Aquatic Herbicide or a premix of the herbicide and water. Manufacturer’s directions and guidelines should be followed when using a polymer.

Invert Application: Harpoon Aquatic Herbicide can be inverted using either tank mix or multi-fl uid mixer techniques with invert oil approved for water and growing crops. For submersed plants, invert application should be made through weighted hoses dragged below the water surface. For heavy infestations, direct application is preferable. Care should be taken to prepare an invert emulsion to provide a heavy viscous consistency.

Suggested mixtures for invert application: For Tank mix systems: Three gallons of invert oil should be blended with 80 gallons of water and 8 gallons of Harpoon Aquatic Herbicide. Bi-fl uid mixer systems: Three gallons of invert oil should be blended with 60 gallons of water and 16 gallons of Harpoon Aquatic Herbicide.


Polymer Application: Harpoon Aquatic Herbicide should be blended with a suitable polymer and applied at a rate of 20 gallons of total spray mix per surface acre. The polymer/herbicide blend must be continuously agitated during the application. Do not apply by aircraft when efficacy at depths below 4 ft. are required. For broader spectrum aquatic weed control, Harpoon Aquatic Herbicide may be tank mixed with other herbicides including diquat, fluridone and endothall. Refer to “Directions for Tank Mixes” for more information. Follow all precautions and guidelines on the labels of any product(s) used with Harpoon Aquatic Herbicide. Correct placement of Harpoon Aquatic Herbicide is essential in order to provide acceptable penetration into plant tissues. Apply Harpoon Aquatic Herbicide when weeds are actively growing, focusing on areas where the greatest concentration of foliage is located. Be certain to apply in such a way as to reach as much of the leafy surfaces as possible. The presence of silt or algae in the water or covering leaves can reduce the effectiveness of the application. In such cases, tank mixing Harpoon Aquatic Herbicide with an algaecide, such as Cutrine-Plus, EPA Reg. No. 8959-10, may improve performance.

Refer to label for more informations.

Limitations, Restrictions, and Exceptions


For Aquatic Weed Control In Quiescent Or Slow Moving Water

Light to Moderate Growth is defined as a treatment area where submersed plants have not reached the water surface (“topped out” and less than 65% of the bottom or water surface (in the case of floating plants) is covered with target plants.

Heavy Infestations is an area where submersed vegetation growth has reached the water surface and/or bottom growth or floating plants cover more than 65% of the treatment area. Do not apply more than 1.0 ppm copper.

Select low range rate for light to moderate growth and upper range rate for heavy infestations.

(Refer in the label for Application Rate Calculations and Tank Mix information.)