MCPA: A Selective Herbicide for Broadleaf Weed Control

Technical Introduction

MCPA (2-methyl-4-chlorophenoxyacetic acid) is a selective systemic herbicide widely used to control broadleaf weeds in cereal crops, pastures, and turf.

It mimics the action of auxin (plant growth hormone), causing uncontrolled growth in susceptible weeds, leading to twisting, stem elongation, leaf cupping, and ultimately death.

• Mode of Action: Synthetic auxin (HRAC Group O, Auxin-type herbicide).

• Systemicity: Systemic; absorbed by leaves and roots, moves through phloem and xylem.

• Selectivity: Kills broadleaf weeds while leaving grasses largely unaffected.

Applications

• Cereal Crops:

  • Commonly applied in wheat, barley, oats, and rye to control dandelions, thistles, chickweed, and wild mustard.

• Pasture Management:

  • Controls broadleaf weeds in grasses and pasturelands.

• Turf and Lawns:

  • Safe for turfgrass; removes clover, plantain, and buttercup.

• Application Timing:

  • Applied post-emergence, when weeds are actively growing and susceptible.

Advantages

• Broadleaf Weed Control: Highly effective against annual and perennial dicots.

• Systemic Action: Absorbed and translocated throughout the weed for complete eradication.

• Crop Safety: Safe for cereal crops and grasses at recommended rates.

• Versatile Formulations: Available as EC, amine salts, and ester formulations for different applications.

• Cost-Effective: Low application rate and broad activity make it economical for large areas.

Specifications (Typical Parameters)

FAQ

Q1: Can MCPA be used in all cereal crops?
A: It is safe for wheat, barley, oats, and rye, but not recommended for legumes or sensitive crops.

Q2: Does it affect grass weeds?
A: No, it is selective for broadleaf weeds; grasses are largely unaffected.

Q3: When is the best time to apply MCPA?
A: Apply post-emergence, when weeds are actively growing and in the seedling or early vegetative stage.

Q4: Can MCPA be combined with other herbicides?
A: Yes, it can be mixed with grass-selective herbicides for broad-spectrum weed control.

Q5: Is MCPA safe for the environment?
A: It has low mammalian toxicity, but care should be taken near water bodies, as it is toxic to aquatic plants and algae.

Q6: What is the typical application rate?
A: Usually 0.5–2 kg a.i./ha, depending on weed pressure and crop growth stage.