Herbicide label

Princep Caliber 90

Princep Caliber 90 (EPA 100-603) is a Group 5 simazine herbicide labeled for 3 crops. The label lists 46 controlled weeds, plus partial-control, suppression, and partner-control categories.

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Official EPA label (PDF)

“This product is noncorrosive to equipment, nonflammable, and has low electrical conductivity.”

— Princep Caliber 90 EPA label, Reg. No. 100-603

Princep Caliber 90 label facts

Crops on the Princep Caliber 90 label

Princep Caliber 90 is labeled for these 3 crops and uses, per the EPA label.

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Weeds on the Princep Caliber 90 label

The Princep Caliber 90 label names 56 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 control46
  • alyssum
  • barnyardgrass, common
  • bluegrass, annual
  • brome, downy
  • burclover
  • carelessweed
  • carpetweed
  • chickweed, common
  • crabgrass
  • rattail fescue
  • fiddleneck
  • filaree, broadleaf
  • fireweed
  • fivehook, bassia
  • foxtail
  • goosegrass
  • groundsel, common
  • hairgrass, silver
  • henbit
  • junglerice
  • knawel
  • lambsquarters, common
  • prickly lettuce
  • morningglory species, annual
  • mustard, tansy
  • mustard, wild
  • nightshade species, annual
  • wild oats
  • paintbrush, flora's
  • panicum, fall
  • pepperweed
  • pepperweed, yellow flower
  • pigweed
  • pineapple-weed
  • purslane, common
  • pusley, florida
  • ragweed, giant
  • redmaids
  • ryegrass, annual
  • shepherd's-purse
  • signalgrass species
  • smartweed species, annual
  • spanishneedles
  • speedwell
  • thistle, russian
  • witchgrass

Partial control

partial3
  • balsamapple vine
  • milkweed, honeyvine
  • spanishneedles

Suppression

suppression1
  • quackgrass

Controls with a tank-mix partner

needs partner8
  • clover species
  • dandelion
  • evening-primrose, cutleaf
  • henbit
  • horseweed
  • lambsquarters
  • puncturevine
  • velvetleaf

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Princep Caliber 90 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 and your soil texture.

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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.

Princep Caliber 90 FAQ

What weeds does Princep Caliber 90 control?

The Princep Caliber 90 label names 56 weeds, including alyssum, common barnyardgrass, annual bluegrass, downy brome, burclover, and carelessweed. Control varies by crop, rate, and timing.

What crops is Princep Caliber 90 labeled for?

Princep Caliber 90 is labeled for 3 crops and uses, including field corn, popcorn, and sweet corn.

What is the active ingredient in Princep Caliber 90? Is it a generic?

Princep Caliber 90's active ingredient is simazine (MOA Group 5). Other products list the same active ingredient; rates, formulations, and labeled crops differ — verify each on its own label.

What's the plant-back interval after Princep Caliber 90?

It depends on your rotational crop, application rate, and region, so the label gives a table, not one number. Build a program and FieldMarshal gives you the exact interval for your rotation from the label line, so you can verify it.

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Can I tank-mix Princep Caliber 90?

It depends on your target weeds, crop stage, and which partners the label approves. Build a program and FieldMarshal checks the label for approved partners and gives the condition on each, so you can verify it.

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Sources

Last updated 2026-07-14.