Herbicide label
IMPACT Herbicide Label
IMPACT (EPA 5481-524) is a Group 27 topramezone herbicide labeled for 6 crops. The label lists 40 controlled weeds, plus partial-control, suppression, and partner-control categories.
“IMPACT is absorbed by leaves, roots, and shoots and translocated to the growing points of sensitive weeds to provide control of emerged weeds.”
IMPACT label facts
- Product IMPACT
- EPA Reg. No. 5481-524
- Registrant Amvac Chemical Corporation
- Active ingredient topramezone
- MOA group 27
Crops on the IMPACT label
IMPACT is labeled for these 6 crops and uses, per the EPA label.
Weeds on the IMPACT label
The IMPACT label names 59 weeds and rates each by how the product handles it: full control, partial control, suppression, or control with a tank-mix partner. A weed can fall at more than one level, because control varies by crop, rate, and timing.
Controls
full control40- amaranth, palmer
- amaranth, powell
- barnyardgrass, common
- buckwheat, wild
- volunteer canola
- carpetweed
- chickweed, common
- cocklebur, common
- crabgrass, large
- crabgrass, smooth
- cupgrass, woolly
- foxtail, giant
- foxtail, green
- foxtail, yellow
- galinsoga, hairy
- goosegrass
- henbit
- jimsonweed
- johnsongrass, seedling
- lambsquarters, common
- prickly lettuce
- horseweed
- millet, wild-proso
- mustard, wild
- nightshade, black
- nightshade, eastern black
- nightshade, hairy
- panicum, fall
- pigweed, prostrate
- pigweed, redroot
- pigweed, smooth
- pigweed, tumble
- pusley, florida
- ragweed, common
- ragweed, giant
- shepherd's-purse
- sunflower, wild
- thistle, russian
- velvetleaf
- waterhemp, common
Partial control
partial7- bindweed, field
- dandelion
- rhizome johnsongrass
- purslane, common
- sandbur, field
- shattercane
- thistle, canada
Controls with a tank-mix partner
needs partner12- burcucumber
- devil's-claw
- kochia
- ladysthumb
- mallow, common
- mallow, venice
- morningglory, entireleaf
- morningglory, ivyleaf
- panicum, texas
- sida, prickly
- signalgrass, broadleaf
- smartweed, pennsylvania
IMPACT rates and plant-back
The label answers both with a table, not a single number. Here is what drives each answer.
Application rate
Your rate depends on your crop.
Get the rate for your field: build a program and FieldMarshal gives you the exact per-acre rate for your crop from the label line.
Plant-back and rotation
Your interval depends on your application rate and the rotational crop.
Get the interval for your rotation: build a program and FieldMarshal gives you the exact plant-back for your rotational crop from the label line.
IMPACT FAQ
What weeds does IMPACT control?
The IMPACT label names 59 weeds, including palmer amaranth, powell amaranth, common barnyardgrass, wild buckwheat, volunteer canola, and carpetweed. Control varies by crop, rate, and timing.
What crops is IMPACT labeled for?
IMPACT is labeled for 6 crops and uses, including field corn, corn silage, seed corn, popcorn, and sweet corn.
What is the active ingredient in IMPACT? Is it a generic?
IMPACT's active ingredient is topramezone (MOA Group 27). Other products list the same active ingredient; rates, formulations, and labeled crops differ — verify each on its own label.
Sources
Last updated 2026-09-30.