Quizalofop-P-Ethyl: A Selective Post-Emergent Herbicide for Grass Weed Control

Definition:
Quizalofop-P-ethyl is a selective post-emergent herbicide used for controlling annual and perennial grass weeds in broadleaf crops. It belongs to the aryloxyphenoxypropionate (FOP) group of herbicides and is highly effective against grassy weeds while being safe for many broadleaf crops.

Chemical Characteristics of Quizalofop-P-Ethyl:

• Chemical Name: (R)-2-[4-(6-chloroquinoxalin-2-yloxy)phenoxy]propionic acid ethyl ester

• Molecular Formula: C19H17ClN2O4

• Molecular Weight: 372.8 g/mol

• Appearance: Light brown to amber-colored liquid (technical concentrate).

• Solubility: Low solubility in water; soluble in organic solvents.

• Stability: Stable under normal storage conditions; sensitive to alkaline conditions.

Mode of Action:

Quizalofop-P-ethyl inhibits acetyl-CoA carboxylase (ACCase), an enzyme essential for fatty acid synthesis in grasses. This disruption halts lipid production required for cell membrane formation, leading to growth inhibition, chlorosis, and weed death. Broadleaf crops are unaffected due to enzyme insensitivity.

Uses and Applications:

1. Target Weeds:

   • Controls annual and perennial grassy weeds such as barnyard grass (Echinochloa spp.), wild oats (Avena spp.), foxtail (Setaria spp.), ryegrass (Lolium spp.), and johnsongrass (Sorghum halepense).

2. Crops:

   • Commonly used in soybean, cotton, peanut, canola, sunflower, sugar beet, and other broadleaf crops.

3. Application Timing:

   • Apply post-emergence to actively growing grass weeds at the 2–6 leaf stage for optimal results.

Benefits of Quizalofop-P-Ethyl:

• Highly Selective: Targets grassy weeds without harming broadleaf crops.

• Effective on Perennials: Provides strong suppression of perennial grasses like johnsongrass.

• Systemic Action: Moves within the plant to control underground shoots and rhizomes.

• Flexible Tank-Mixing: Can be combined with broadleaf herbicides for complete weed control programs.

Limitations:

• No Broadleaf Weed Control: Ineffective on broadleaf weeds, requiring supplemental herbicides.

• Resistance Risk: Overuse may lead to ACCase-resistant grass populations.

• Slow Visual Symptoms: Weed death may take 10–14 days to become visible.

• Sensitive Crops: Should not be used in grass crops like maize, rice, or wheat.

Recommended Application:

• Dosage: 0.05–0.15 kg active ingredient per hectare, depending on weed species and growth stage.

• Method: Foliar spray with thorough coverage; use recommended adjuvants for better absorption.

• Precautions:

  • Apply to actively growing weeds under favorable conditions.

  • Avoid spray drift to grass crops or pastures.

  • Rotate with herbicides of different modes of action to prevent resistance.

Storage and Handling:

• Storage: Store in sealed containers, away from sunlight and moisture.

• Shelf Life: Typically stable for 2–3 years under proper storage conditions.

• Safety: Low mammalian toxicity; appropriate protective gear (gloves, masks) is required during handling.

FAQ on Quizalofop-P-Ethyl:

Q1: What weeds does Quizalofop-P-ethyl control?
A1: It controls a wide range of annual and perennial grassy weeds, including barnyard grass, foxtail, and johnsongrass.

Q2: Can it be used on cereals or maize?
A2: No, it is only safe for broadleaf crops and will damage cereals and other grass crops.

Q3: How quickly does it work?
A3: Weed growth stops within a few days, with visual symptoms (yellowing and wilting) appearing in 10–14 days.

Q4: How is it different from other grass herbicides?
A4: It offers strong systemic control of perennial grasses and is widely used in broadleaf crop rotations.