Herbicide label
Prefix Herbicide Label
Prefix (EPA 100-1268) is a Group 14 and 15 fomesafen and metolachlor herbicide labeled for 2 crops. The label lists 29 controlled weeds, plus partial-control, suppression, and partner-control categories.
“Prefix Herbicide is a selective herbicide for the control or partial control of certain grass, broadleaf and sedge weeds in soybeans and cotton.”
Prefix label facts
- Product Prefix
- EPA Reg. No. 100-1268
- Registrant Syngenta Crop Protection, LLC
- Active ingredient fomesafen and metolachlor
- MOA group 14 and 15
Crops on the Prefix label
Prefix is labeled for these 2 crops and uses, per the EPA label.
Weeds on the Prefix label
The Prefix label names 44 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 control29- barnyardgrass, common
- carpetweed
- crabgrass spp.
- crowfootgrass
- cupgrass, prairie
- cupgrass, southwestern
- ecliptia
- foxtail spp.
- galinsoga spp.
- goosegrass
- junglerice
- lambsquarters, common
- nightshade, eastern black
- panicum, fall
- pennycress, field
- pepperweed, virginia
- pigweed spp.
- poinsettia, wild
- purslane, common
- pusley, florida
- ragweed, common
- redweed
- signalgrass, broadleaf
- smartweed, ladysthumb
- smartweed, pennsylvania
- spurge, spotted
- starbur, bristly
- waterhemp, common
- witchgrass
Partial control
partial15- cocklebur, common
- horseweed
- jimsonweed
- johnsongrass, seedling
- morningglory
- nightshade, hairy
- nutsedge, yellow
- panicum, texas
- ragweed, giant
- red rice
- sandbur spp.
- shattercane
- sida, prickly/teaweed
- sunflower, annual
- velvetleaf
Prefix 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.
Prefix FAQ
What weeds does Prefix control?
The Prefix label names 44 weeds, including common barnyardgrass, carpetweed, crabgrass spp., crowfootgrass, prairie cupgrass, and southwestern cupgrass. Control varies by crop, rate, and timing.
What crops is Prefix labeled for?
Prefix is labeled for 2 crops and uses, including soybeans and cotton.
What is the active ingredient in Prefix? Is it a generic?
Prefix's active ingredient is fomesafen and metolachlor (MOA Group 14 and 15). 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.