Pretilachlor: A Selective Pre-Emergence Herbicide for Paddy Fields

Technical Introduction

Pretilachlor is a selective pre-emergence chloroacetamide herbicide widely used for weed management in transplanted rice fields. It is absorbed primarily through the roots and shoots of germinating weeds, disrupting cell division and elongation.

• Mode of Action (MOA): Inhibits fatty acid elongation and lipid biosynthesis, affecting cell division and membrane formation in weeds.

• Selectivity: Rice plants metabolize Pretilachlor rapidly, allowing them to tolerate field application.

• Formulation: Available in 50% EC (emulsifiable concentrate) and 10% GR (granules).

Applications

• Crops: Paddy rice (transplanted and direct-seeded in flooded conditions).

• Weeds Controlled:

  • Grasses:Echinochloa crus-galli (barnyardgrass), Leptochloa chinensis, Panicum spp.

  • Sedges:Cyperus difformis, Fimbristylis miliacea

  • Broadleaf weeds:Ammania baccifera, Eclipta prostrata, Monochoria vaginalis

• Application Timing:

  • Applied pre-emergence within 3–5 days after transplanting rice seedlings.

  • Works best when fields remain flooded for at least 5–7 days after application.

Advantages

• Highly Selective for Rice: Safe for transplanted seedlings.

• Broad-Spectrum Control: Effective against most grasses, sedges, and some broadleaves.

• Long Residual Effect: Controls weeds for 4–6 weeks, reducing early weed competition.

• Flexible Formulations: Available as liquid (EC) or granule (GR) for ease of application.

• Labor-Saving: Reduces manual weeding requirements in paddy fields.

Specifications (Typical Parameters)

FAQ

Q1: How is Pretilachlor different from Butachlor (Machete)?
A: Pretilachlor is considered more effective on sedges and broadleaf weeds than Butachlor and requires a lower application rate.

Q2: Can Pretilachlor be used in dry-seeded rice?
A: It is most effective in transplanted flooded rice; efficacy in dry-seeded rice is limited.

Q3: How long does it protect rice crops?
A: Provides 4–6 weeks of weed suppression, covering the critical early growth stage of rice.

Q4: Can it be mixed with other herbicides?
A: Yes, often mixed with bensulfuron-methyl to broaden control against stubborn broadleaf weeds.

Q5: Does resistance occur?
A: Resistance is relatively low, but long-term continuous use may select for tolerant weed species; rotation with other herbicides is recommended.