Clodinafop-Propargyl: A Selective Post-Emergent Grass Herbicide

Definition:
Clodinafop-propargyl is a selective post-emergent herbicide used primarily for controlling annual grass weeds in cereal crops such as wheat and barley. It belongs to the aryloxyphenoxypropionate (FOP) class of herbicides and is designed to target grass weeds without damaging broadleaf crops.

Chemical Characteristics of Clodinafop-Propargyl:

• Chemical Name: (R)-2-[4-(5-chloro-3-fluoro-2-pyridyloxy)phenoxy]propionic acid propargyl ester

• Molecular Formula: C17H13ClFNO4

• Molecular Weight: 349.74 g/mol

• Appearance: Pale yellow to amber-colored liquid (technical concentrate).

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

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

Mode of Action:

Clodinafop-propargyl inhibits acetyl-CoA carboxylase (ACCase), a key enzyme involved in fatty acid synthesis in grasses. This inhibition disrupts cell membrane formation and growth, ultimately killing grass weeds. Broadleaf crops remain unaffected because their ACCase enzyme is not sensitive to this herbicide.

Uses and Applications:

1. Target Weeds:

   • Effective against major grass weeds such as wild oat (Avena fatua), canary grass (Phalaris spp.), ryegrass (Lolium spp.), and barnyard grass (Echinochloa spp.).

2. Crops:

   • Commonly applied in wheat, barley, rye, and triticale.

3. Application Timing:

   • Best applied post-emergence when grass weeds are in the 2–4 leaf stage and actively growing.

Benefits of Clodinafop-Propargyl:

• High Selectivity: Targets grasses while being safe on labeled cereal crops.

• Effective Control: Provides excellent control of annual grasses in wheat fields.

• Flexible Mixing: Can be tank-mixed with broadleaf herbicides for complete weed control.

• Low Crop Injury Risk: When applied as directed, crop tolerance is high.

Limitations:

• No Broadleaf Weed Control: Must be used in combination with broadleaf herbicides if mixed infestations exist.

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

• Weather Sensitivity: Performance may be reduced under cold, drought-stressed conditions.

• Not Suitable for Oats: Can injure or kill oat crops.

Recommended Application:

• Dosage: 0.05–0.125 kg active ingredient per hectare, depending on target weed species and density.

• Method: Foliar spray with fine droplet coverage; use adjuvants (e.g., surfactants) to improve absorption.

• Precautions:

  • Apply to actively growing weeds for best efficacy.

  • Avoid drift to sensitive crops such as maize or rice.

  • Follow resistance management practices, including rotating herbicides.

Storage and Handling:

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

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

• Safety: Low acute toxicity to humans; wear protective clothing during mixing and application.

FAQ on Clodinafop-Propargyl:

Q1: What type of weeds does Clodinafop control?
A1: It selectively controls annual grasses such as wild oats, ryegrass, and canary grass in wheat and barley.

Q2: Does Clodinafop affect broadleaf weeds?
A2: No, it is only effective on grass weeds and must be combined with other herbicides for broadleaf control.

Q3: How does Clodinafop work?
A3: It inhibits the ACCase enzyme in grasses, disrupting fatty acid synthesis and causing weed death.

Q4: Can it be used in oats or maize?
A4: No, it is not safe for oats or maize and should be applied only in labeled cereal crops.