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Grassy Post-Emergent Herbicides

Grassy post-emergent herbicides are used to control grassy weeds that are already visible above the soil. These products do not prevent weeds and do not replace pre-emergent programs.

Correct control depends on:

  • Turf species

  • Whether the grass weed is annual or perennial

  • Growth stage

  • Temperature and turf health

✅ GOOD

Entry-Level Annual Grassy Weed Control

Products

  • Quinclorac 75DF

  • Quintessential (Quinclorac liquid)

  • Q4 Plus (contains quinclorac)

Typical Rate

  • 0.75 – 1.5 oz per 1,000 sq ft
    (Adjuvant required for best results)

Timing

  • Best on young, actively growing grasses

  • Spring through early summer

  • Air temperatures 65 - 85°F

Turf Sensitivity

  • Bermuda: Safe

  • Zoysia: Safe

  • St. Augustine: Use caution, label dependent

  • Fescue: Label dependent

What GOOD does well

  • Crabgrass

  • Smooth crabgrass

  • Some signalgrass

  • Early goosegrass

Limits

  • Weak on mature plants

  • Weak on perennial grasses

  • Repeat applications often needed

Counter explanation

“This works best when the grass is young. Once it matures, we need to step up.”

✅ BETTER

Workhorse Grassy Weed Control

Products

  • Revolver (Foramsulfuron)

  • Pastora

  • Fusilade II / Fusilade DX

  • Ornamec 170

  • Katana

Typical Rate

  • Revolver: ~0.1 – 0.6 oz per 1,000 sq ft

  • Fluazifop products: label-specific, low rate

  • Pastora / Katana: low-rate, measured carefully

Timing

  • Turf actively growing

  • Best results when weeds are not stressed

  • Morning applications preferred

Turf Sensitivity

  • Bermuda: Excellent tolerance

  • Zoysia: Label dependent

  • St. Augustine:

    • Fluazifop products are NOT labeled

    • Revolver is Bermuda only

  • Cool-season turf: Label dependent

Strengths

  • Better control of mature grasses

  • Controls difficult annual grasses

  • Some suppression of perennial grasses

Counter explanation

“This is stronger control for grasses that are past the seedling stage.”

✅ BEST

Professional / Perennial Grassy Weed Control

Products

  • MSMA (Golf Course Only)

  • Certainty

  • Kerb SC (RUP)

  • Telar XP (limited grassy activity)

Typical Rates

  • Certainty: 0.75 – 1.25 grams per 1,000 sq ft

  • MSMA: golf-only, label specific 2 oz per 1000 sq ft 3 applications 7 days apart. 

  • Kerb SC: restricted use, temperature critical

Timing

  • Turf must be healthy

  • Often requires multiple applications

  • Timing is critical, especially for perennials

Turf Sensitivity (Very Important)

  • Bermuda: Primary target turf

  • Zoysia: Label dependent

  • St. Augustine: Limited or NOT labeled

  • Fescue: Label dependent

What BEST does well

  • Dallisgrass suppression

  • Johnsongrass suppression

  • Tough perennial grasses

  • Grasses resistant to quinclorac

Important Truth
Perennial grassy weeds are not quick fixes. Control takes time, repeat applications, and strong turf competition.

Counter explanation

“Perennial grasses don’t die easy. This is a program, not a one-spray solution.”

Common Reasons Grassy Weed Control Fails

  • Waiting too long to spray

  • Misidentifying annual vs perennial grasses

  • Skipping adjuvants

  • Spraying stressed turf

  • Poor mowing and irrigation practices

➡ Link: Lawn Care 101 BMP

Summary for Staff

  • GOOD: Young annual grasses

  • BETTER: Mature annual grasses

  • BEST: Perennial grasses and resistant weeds

Correct identification comes before product choice.

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