NC State Extension Publications


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Trade Name: Reward Common Name: diquat dibromide Formulations: 2L

Nonselective, postemergence weed control for use in field and container nurseries, landscape beds, walkways, patios, beneath greenhouse benches, along driveways, and other non-crop areas. Rapid burn-down of weeds with no soil residual. Cool weather does not reduce the efficacy of Reward as dramatically as other postemergence herbicides. For this reason, Reward is often used in the winter and early spring to control winter annual weeds.

Amount of Active Ingredient Amount by Formulation
2 L
Per Acre 0.25 to 1 0.5 to 2 qt
Per 100 gal 0.5 to 1.0 lb 1 to 2 qt
Per 1 gal 0.166 fl oz 4 teaspoons

seedling weeds are necrotic; nontreated weeds green

Nonselective control of seedling weeds. Photo taken 3 days after diquat application.

J. Neal  CC BY-NC-ND 4.0

most weeds are dead, but regrowth is happening at the base of a larger weed

Diquat is a contact action herbicide. Larger weeds or those not contacted by spray can re-grow.

J. Neal  CC BY-NC-ND 4.0

Major Weeds Controlled

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Nonselective postemergence control of seedling broadleaves and grasses.

Major Weeds Not Controlled

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Provides only "top-kill" of perennial weeds and most established annual weeds. Has no soil residual and thus does not affect weeds that emerge after application. Addition of a systemic herbicide in a tank-mix with Reward may be needed for control of established perennial weeds.

green growth at the center of a crabgrass plant previously treated with diquat

Grasses often survive diquat applications because the growing points are protected from contact with the spray.

J. Neal  CC BY-NC-ND 4.0

crabgrass regrowth

Even 2 applications of diquat did not completely kill crabgrass in this demonstration.

J. Neal  CC BY-NC-ND 4.0

For Best Results

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A 75 percent nonionic surfactant should be added to the spray solution. Apply for full coverage and thorough weed contact in a minimum of 15 gallons of spray per acre. Higher spray volumes have provided more consistent weed control in North Carolina tests. Best control is achieved if weeds are young when treated. Re-treatment may be necessary for grasses and established weeds.

Cautions and Precautions

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Avoid spray contact with desirable vegetation.

Residual Activity

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Volatility and Leaching Potential

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Nonvolatile. Strongly adsorbed by clay particles in the soil; little leaching expected.

Symptoms and Mode of Action

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Interacts with light to produce superoxides that destroy plant cells. On a sunny day, treated tissues will appear water-soaked within hours. Necrosis follows within one or two days. Dead tissue usually turns black. WSSA Group 22. See Photosystem I, Bipyridillium Herbicides.

Additional Information

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Worker Protection Standards REI: 24 hours
PPE: coveralls, chemical-resistant gloves, water-proof footwear + socks, headgear for overhead exposure, apron when cleaning equipment, mixing, or loading, face shield when mixing or loading, protective eyewear
Manufacturer: Syngenta Crop Protection, LLC EPA Reg. # 100-1091


Professor of Weed Science, Extension Specialist & Department Extension Leader
Horticultural Science
Assistant Professor – Ornamental, Landscape and Invasive Weed Management
University of Florida

Publication date: March 20, 2018
Revised: Dec. 21, 2022

Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by NC State University or N.C. A&T State University nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your local N.C. Cooperative Extension county center.

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