Crabgrass (Large & Smooth)
Digitaria sanguinalis / ischaemum
Crabgrass (Large & Smooth) (Digitaria sanguinalis / ischaemum) is a summer annual grassy weed characterized by spreading prostrate stems forming crab-like star clusters; light yellow-green wide blades; branched finger-like seed spikes.. It anchors via a fibrous roots root system and is selectively controlled using Prodiamine / Dithiopyr (Pre-emergent at 55°F soil temp); Quinclorac (Drive XLR8) or Tenacity (Post-emergent) applied during apply pre-emergent in spring when forsythia blooms and soil reaches 55°f for 3 consecutive days..
Prodiamine / Dithiopyr (Pre-emergent at 55°F soil temp); Quinclorac (Drive XLR8) or Tenacity (Post-emergent)
Spreading prostrate stems forming crab-like star clusters; light yellow-green wide blades; branched finger-like seed spikes.
Always read and follow the manufacturer's EPA-approved pesticide product label. The label is the law under federal FIFRA (Federal Insecticide, Fungicide, and Rodenticide Act) regulations. Application rates, personal protective equipment (PPE), target weed maturity stages, temperature restrictions, and grazing or re-entry intervals specified on the EPA container label supersede all online recommendations. Local state regulations may restrict certain active ingredients.
University-Verified Herbicide Formulations
Professional active formulations cross-referenced against university weed science trials.
Tenacity Herbicide (Mesotrione 8 oz)
Active: 40% Mesotrione Selective Systemic
Gold standard selective pre- and post-emergent targeting crabgrass, ground ivy, yellow nutsedge, and clover during overseeding.
SedgeHammer+ Turf Herbicide (Halosulfuron 0.5 oz)
Active: 5% Halosulfuron-methyl with Surfactant
Pre-mixed with surfactant for 1-gallon sprayers. Translocates into underground nutlets without injuring cool or warm season lawns.
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Botanical Identification Key for Crabgrass (Large & Smooth)
Accurately identifying Digitaria sanguinalis / ischaemum is essential because spraying non-selective chemicals like glyphosate risks killing desirable lawn grass. Look for these botanical hallmarks:
- Foliar Morphology: Spreading prostrate stems forming crab-like star clusters; light yellow-green wide blades; branched finger-like seed spikes..
- Root Architecture: Anchored by a fibrous roots, making manual pulling ineffective unless the entire root crown is extracted.
- Growth Period: Active during summer annual cycles, flourishing when lawn turf is stressed or cut too short.
Eradication Protocol & Selective Herbicide Selection
To eradicate Crabgrass (Large & Smooth) while preserving your lawn turfgrass, apply Prodiamine / Dithiopyr (Pre-emergent at 55°F soil temp); Quinclorac (Drive XLR8) or Tenacity (Post-emergent) during Apply pre-emergent in spring when forsythia blooms and soil reaches 55°F for 3 consecutive days.. Ensure that the active ingredients match your host turfgrass tolerances:
- Temperature Safety Band: Apply when ambient air temperatures range between 65°F and 85°F. Never apply volatile ester herbicides in temperatures exceeding 85°F to prevent herbicide vapor drift and leaf burn.
- Adjuvant / Surfactant: For waxy or hairy weed foliage, mix with a methylated seed oil (MSO) or non-ionic surfactant according to EPA label instructions to enhance chemical cuticle penetration.
- Mowing Holdback: Do not mow the lawn 2 days prior to spraying or 2 days after application to maximize foliar surface area for chemical absorption.
Frequently Asked Questions About Crabgrass (Large & Smooth)
01 How do I kill Crabgrass (Large & Smooth) without harming my lawn?
Use a selective herbicide labeled for your specific turfgrass species containing Prodiamine / Dithiopyr (Pre-emergent at 55°F soil temp); Quinclorac (Drive XLR8) or Tenacity (Post-emergent). Spray when Crabgrass (Large & Smooth) is actively growing during apply pre-emergent in spring when forsythia blooms and soil reaches 55°f for 3 consecutive days.. Always check your host grass in our weed triage tool before application.
02 Why does pulling Crabgrass (Large & Smooth) by hand often fail?
Crabgrass (Large & Smooth) anchors via a fibrous roots. Hand-pulling often breaks the crown or leaves underground root fragments, rhizomes, or nutlets behind, which triggers rapid regrowth. Systemic selective herbicides translocate down through the vascular tissue to destroy the entire root structure.
03 What class of weed is Crabgrass (Large & Smooth)?
Crabgrass (Large & Smooth) is classified botanically as a Grassy weed with a Summer Annual life cycle.
04 When is the best time of year to treat Crabgrass (Large & Smooth)?
The optimal eradication window is Apply pre-emergent in spring when forsythia blooms and soil reaches 55°F for 3 consecutive days.. Applying when temperatures are between 60°F and 85°F ensures maximum chemical absorption and prevents foliar heat stress to your desirable lawn.