IMPACT Herbicide

IMPACT® Herbicide

Proven Performance in Postemergence Control

Postemergency Application Guidelines In Corn

Labeled Crops
  • All hybrids and inbreds of field corn, food grade corn, sweet corn and popcorn.
Active Ingredient
  • IMPACT contains 2.8 lb of topramezone, the active ingredient, per gallon.
  • The product is formulated as a suspension concentrate, an easy-to-pour liquid.
Recommended Rate
  • 0.75 fl oz per acre; up to 1 fl oz per acre may be applied under a supplemental label.
Tank Additives for Best Performance
  • MSO at 1 gal/100 gal plus UAN at 3 pt per acre or AMS at 2.0 to 2.5 lb per acre.
  • Use additives recommended on the Roundup® label when tank-mixing with IMPACT.
  • COC may be substituted for MSO if required by tank mix partner.
Tank Mix Partners
  • Atrazine is recommended at 0.25 to 1.5 lb per acre for added burndown & residual.
  • Postemergence grass and broadleaf corn herbicides unless restricted on the label.
  • Soil residual herbicides labeled for early postemergence application to corn.
Application Window
  • Optimum timing is 4 to 12-inch corn and 2 to 6-inch weeds.
  • IMPACT may be applied up to 45 days before harvest.
  • Observe preharvest interval of any tank-mix partners with IMPACT.
Application Directions
  • Recommended gallonage: 15 gpa minimum by ground and 3 gpa minimum by air.
  • Weeds must be thoroughly covered with spray for best control.
  • Drop nozzles and/or higher gallonage are recommended if the crop canopy prevents adequate spray coverage of weeds.
  • Application should be made a minimum of one hour before rainfall or irrigation.
  • Application should be made to corn when weeds are actively growing.
Insecticide Guidelines
  • No restrictions.
Label Restrictions & Precautions
  • Avoid cultivating for at least 7 days before or after application.
  • Do not graze or feed treated corn for at least 45 days after application.
  • See federal label for precautions regarding specific herbicide partners.
Crop Rotation
  • Refer to IMPACT federal and supplemental labels for rotational crop guidelines.
  • Restricted entry interval (REI) is 12 hours.
PPE for Early Entry
  • Personal Protective Equipment (PPE) for early entry: Coveralls, shoes plus socks, chemical-resistant gloves Category A.
Spray Equipment Cleaning
  • Clean spray equipment thoroughly before and after application using a strong detergent or commercial spray tank cleaner to avoid risk of injury to sensitive crops.
Product Storage Guidelines
  • Store product in a cool, dry place. If product has been stored under freezing temperatures, shake or mix contents of container completely before using.

IMPACT® Herbicide — Postemergence Application Guidelines in Corn

Broadleaf Weeds Controlled by IMPACT at 0.5 or 0.75 fl oz/a and Maximum Recommended Weed Height in Inches at Application1

Annual Broadleaf Weeds Maximum Size (Inches)
0.5 fl oz/a 0.75 fl oz/a
Amaranth, Palmer 4" 6"
Amaranth, Powell 4" 6"
Burcucumber 4" 6"
Carpetweed 4" 6"
Chickweed, Common 2" 4"
Cocklebur, Common 5" 8"
Dandelion* 4" 6"
Galinsoga, Hairy 4" 6"
Horseweed (Marestail) 4" 6"
Henbit 2" 4"
Jimsonweed 4" 6"
Kochia 4" 6"
Lambsquarters, Common 4" 6"
Lettuce, Prickly 3" 4"
Mallow, Common 2" 3"
Mallow, Venice* 2" 3"
Morningglory sp.* 4" 6"
Mustard sp. 4" 6"
Nightshade, Black 4" 6"
Nightshade, Eastern Black 4" 6"
Nightshade, Hairy 4" 6"
Pigweed, Prostrate 4" 6"
Pigweed, Redroot 4" 6"
Pigweed, Smooth 4" 6"
Pigweed, Tumble 2" 4"
Pusley, Florida 2" 3
Ragweed, Common 4" 6"
Ragweed, Giant 5" 8"
Shepardspurse 2" 4"
Sida, Prickly 2" 3"
Smartweed, Ladysthumb 2" 3"
Smartweed, Pennsylvania 2" 3"
Sunflower, Volunteer 5" 8"
Sunflower, Wild (common) 5" 8"
Thistle, Canada* 4" 6"
Thistle, Russian 2" 4"
Velvetleaf 4" 8"
Waterhemp, Common 4" 6"
Waterhemp, Tall 4" 6"


Grass Weeds Controlled by IMPACT at at 0.75 or 1.0 fl oz/a and Maximum Recommended Weed Height in Inches at Application1

  IMPACT at 0.75 fl oz/a IMPACT at 1.0 fl oz/a
Barnyardgrass 4" 4"
Crabgrass, Large 3" 3"
Crabgrass, Smooth 3" 3"
Cupgrass, Woolly PC† 3"
Foxtail, Giant 4" 4"
Foxtail, Green 3" 3"
Foxtail, Yellow PC† 3"
Goosegrass 3" 3"
Johnsongrass, Seedling PC† 4"
Millet, Wild-Proso 3" 3"
Panicum, Fall PC† 3"
Panicum, Texas S S
Shattercane S S
Signalgrass, Broadleaf PC† 3"

IMPACT — The Roundup® Tank Mix Partner of Choice™

  • Weed Resistance Management Programs in Glyphosate Tolerant Corn Hybrids
  • Apply IMPACT at 0.5 - 0.75 fl oz/a in tank mixtures with glyphosate for control of glyphosate tolerant or resistant weed species.
  • Use spray adjuvant, and include ammonium sulfate, as recommended on the glyphosate product label.

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PROVEN PERFORMANCE in Postemergence Control

  • Excellent control of broadleaf weeds — remarkable grass control.
  • IMPACT sets the standard for safety in all types of corn: field; seed; sweet; and popcorn.
  • Incinerates tough to control broadleaf weeds including tolerant species such as waterhemp, ragweeds, pigweeds, lambsquarters, velvetleaf, kochia and more.
  • IMPACT is the only tank-mix partner recommended by Monsanto in the Roundup Ready® Plus program.

Smashing Results

Unequalled Safety in Corn — Real IMPACT on Yields

Freedom of Choice: Application Timing-Tank Mix Options -Rotational Flexibility

IMPACT puts you in control. From application timing, tank mix partners, corn safety and rotational practices, IMPACT gives you a wide-range of options:

  • Apply anytime after corn emergence until 45 days before harvest — early to late post.
  • Excellent performance in a two-pass program following a soil applied herbicide
  • Compatible in tank mixes with postemergence corn herbicides.
  • May be used to control emerged weeds in early postemergence programs in tank mixes with residual herbicide(s).
  • Provides enhanced value in tank mixes with atrazine for applications up to 12" corn.
  • Low use rates offer convenience and an SC formulation allows for easy mixing.
  • Can be used safely with soil and foliar insecticide programs in corn.
  • Labeled for use on Roundup Ready®, LibertyLink® and Clearfield® hybrids.
  • Fits weed resistance management programs.
  • May be applied to inbred lines used in field corn, sweet corn and popcorn seed production.
  • Provides flexibility with major rotational cropping.
Broadleaf Weeds Controlled

IMPACT Controls Key Grass Weeds

The unique chemistry of IMPACT herbicide not only controls tough broadleaf weeds, it provides extra power that cleans up problem grasses in corn.

Grass Weeds Controlled
  • Barnyardgrass
  • Crabgrass, Large and Smooth
  • Cupgrass, Woolly**
  • Foxtail, Giant and Green
  • Foxtail, Yellow**
  • Goosegrass
  • Johnsongrass, Seedling**
  • Millet, Wild-Proso
  • Panicum, Fall**
  • Shattercane*
  • Signalgrass, Broadleaf**

IMPACT — Now That's Good Chemistry

Unique HPPD-Inhibitor — the active ingredient Topramezone gives IMPACT the power to control both broadleaf and grass weeds with unequalled crop safety. IMPACT herbicide is the safe choice on all types of corn including field corn, seed corn,sweet corn and popcorn.

Rates and Additives — For best results, apply IMPACT herbicide at 0.75 fl oz/ac + MSO at 1 gal/100 gal + Ammonium sulfate (AMS) at 2.5 lb per acre (liquid AMS at equivalent rates may be used). When treating corn up to 12 inches tall, atrazine at 0.25 - 1.5 lb/ac may be added to the mixture for improved burndown and added soil residual weed control.

Get more out of your postemergence program-get the proven performance and the standard in corn safety — IMPACT herbicide.

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Field Corn · Food-Grade Corn · Sweet Corn · Popcorn · Seed Corn

IMPACT® Herbicide:

  • A powerful broad spectrum herbicide with no known weed resistance.
  • Uniquely safe for use in all types of corn.
  • Controls many emerged annual grass weeds including foxtails, crabgrass, fall panicum, barnyardgrass and broadleaf signalgrass.
  • Postemergence control of over 40 broadleaf weed species including the common and troublesome weeds such as pigweeds, waterhemp, lambsquarters, ragweeds, velvetleaf and many more.
Excellent crop safety with outstanding postemergence control of grass and broadleaf weeds in all types of corn
  • Field Corn — all hybrids
  • Food-Grade Corn — all yellow and white hybrids
  • Sweet Corn — all processing and fresh market hybrids
  • Popcorn — all yellow and white hybrids
  • Seed Corn — inbred lines
Best agronomic use recommendation for full season weed control and maximized crop yield results is a planned two-pass program:

Step 1 — Apply a preemergence herbicide(s) at rates that provide early season control.

Step 2 — Apply IMPACT postemergence to keep your fields clean through harvest.

Application Timing
  • Apply IMPACT from anytime after weeds and grasses emerge up to 45 days prior to harvest.
  • For best performance and maximum yields, apply IMPACT when weeds are small — before they compete for moisture and nutrients with your crop.
Application Information
  • Apply IMPACT at 0.75 to 1.0 fluid ounces per acre
  • Spray adjuvants:
    • MSO (1 gal/100 gal) or COC (1 gal/100 gal) plus
    • UAN (2.5% v/v) or AMS (8.5 lb/100 gal)
  • Add atrazine at 0.25 -1.5 pounds active ingredient per acre for applications up to 12-inch tall corn

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