# IMPACT HERBICIDE

- EPA Reg No: **5481-524**
- Registrant: AMVAC CHEMICAL CORPORATION
- Signal word: Caution
- Active ingredients: Topramezone (29.7%)
- Label accepted: 2021-03-11
- Source PDF: https://www3.epa.gov/pesticides/chem_search/ppls/005481-00524-20210311.pdf

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524-20210310 Page 1 of 3 
IMPACT Herbicide
EPA REG. NO. 5481-524 
 
SUPPLEMENTAL LABEL 
For control of emerged weeds 
in all corn types
 
SUPPLEMENTAL LABEL 
Increased maximum single and annual use rate in corn to 2.0 fluid ounce 
(0.044 lb topramezone) per acre. 
EPA Reg. No.: 5481-524
Directions for Use 
This supplemental label expires April 1, 2024 and must not be used or distributed after this 
date. 
 
It is a violation of Federal law to use this product in a manner inconsistent with its labeling. 
 
THIS LABEL MUST BE IN THE POSSESSION OF THE USER AT THE TIME OF APPLICATION. 
 
Before applying IMPACT please read the complete label affixed to the product container. All 
applicable directions, restrictions and precautions on the EPA-registered label are to be followed. Use 
of IMPACT according to this supplemental labeling is subject to the use precautions and limitations 
imposed by the label on the container. 
 
IMPORTANT: Read the entire Directions for Use and the Limited Warranty and Disclaimer on the EPA-
registered IMPACT herbicide label before using this product. 
 
Use Information 
For use in FIELD CORN (grown for grain, silage or seed), POPCORN (ear, kernel or seed) and SWEET 
CORN (ear, kernel or seed). 
Table 1. Emerged Broadleaf Weeds Controlled or Partially Controlled with IMPACT and Maximum 
Weed Size at Application 
Broadleaf Weeds1
IMPACT 
0.75 fl oz per acre 
IMPACT 
1.0 fl oz per acre 
2 2 
Amaranth, Palmer C C 
Amaranth, Powell C C
Bindweed, field PC PC

524-20210310 Page 2 of 3 
Broadleaf Weeds1
IMPACT
0.75 fl oz per acre
IMPACT
1.0 fl oz per acre
2 2 
Burcucumber C 3,4 C 4 
Buckwheat, wild NC C 3,4
Canola, volunteer C C
Carpetweed C C
Chickweed, common C C 
Cocklebur, common C C 
Dandelion PC PC
Devil’s-claw C 3,4 C 4 
Galinsoga, hairy C C 
Henbit C C 
Jimsonweed C C 
Kochia C 4 C 4 
Ladysthumb C 4 C 4 
Lambsquarters, common C C 
Lettuce, prickly C C
Mallow, common C 3,4 C3,4
Mallow, Venice C 3,4 C 3,4
Marestail (horseweed) C C
Morningglory, entireleaf C 3,4 C 3,4
Morningglory, ivyleaf C 3,4 C 3,4
Mustard, wild C C 
Nightshade, black C C
Nightshade, Eastern black C C
Nightshade, hairy C C
Pigweed, prostrate C C
Pigweed, redroot C C
Pigweed, smooth C C
Pigweed, tumble C C
Purslane, common PC 3 C3,4
Pusley, Florida C 3 C
Ragweed, common C C
Ragweed, giant C C
Shepherd’s-purse C C
Sida, prickly C 3,4 C 4 
Smartweed, Pennsylvania C 4 C 4 
Sunflower, wild (common) C C
Thistle, Canada PC 3 PC 
Thistle, Russian C C
Velvetleaf C C
Waterhemp, common C C
Waterhemp, tall C C
1Refer to Section X for a list of scientific names on the EPA label. 
2Broadleaf Weed Rating: C=Control; PC=Partial Control; NC=Not Controlled. 
3Apply before weed exceeds 3 inches in height. 
4 rol.

524-20210310 Page 3 of 3 
Table 2. Emerged Grass Weeds Controlled or Partially Controlled with IMPACT at 0.75 to 2.0 fl oz/A 
and Maximum Weed Size at Application 
Grass Weeds1
IMPACT 
0.75 fl oz per acre 
IMPACT 
1.0 fl oz per acre 
IMPACT 
1.5 – 2.0 fl oz per acre 
2 2 2
Barnyardgrass C 5 C C 
Crabgrass, large C 5 C 5 C 
Crabgrass, smooth C 5 C 5 C 
Cupgrass, woolly PC C 3 C 
Foxtail, giant C C C 
Foxtail, green C 5 C C 
Foxtail, yellow PC C 3,5 C 
Goosegrass C C C 
NC NC PC 4 
Johnsongrass, seedling PC C C
Millet, wild-proso C C C 
Panicum, fall PC C 3,5 C 
Panicum, Texas PC PC C 4,5 
Sandbur, field NC PC C 4,5 
Shattercane PC PC C 4,5 
Signalgrass, broadleaf PC C 3,5 C 5
1Refer to Section X for a list of scientific names on the EPA label. 
2Grass Weed Rating: C=Control; PC=Partial Control; NC = Not Controlled. 
3Apply before grass exceeds 3 inches in height. 
4 
5 
 
Restrictions 
 the 
equivalent of 2.0 fluid ounces of IMPACT per acre. 
 DO NOT apply IMPACT within 45 days of corn harvest (fresh market sweet corn, silage, fodder, 
or grain). 
 an 
application of IMPACT. 
 DO NOT apply this product through any type of irrigation system. 
©2020 AMVAC Chemical Corporation is a wholly owned subsidiary of American Vanguard Corporation. All Rights Reserved. 
AMVAC, Impact, and their respective logos are trademarks owned by AMVAC Chemical Corporation. 
Registrant: 
AMVAC Chemical Corporation 
MacArthur Court, Suite 1200