Bromoxynil Octanoate: A Contact Herbicide for Broadleaf Weed Control

Definition:
Bromoxynil Octanoate is a contact post-emergent herbicide primarily used to control annual broadleaf weeds in cereal crops, corn, and non-crop areas. It is an ester formulation of bromoxynil, designed for improved penetration and efficacy against tough broadleaf weeds.

Chemical Characteristics:

• Chemical Name: 3,5-Dibromo-4-hydroxybenzonitrile octanoate

• Molecular Formula: C15H15Br2NO3

• Molecular Weight: 433.1 g/mol

• Appearance: Amber-colored liquid

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

• Stability: Stable under normal conditions but degrades in alkaline environments

Mode of Action:

Bromoxynil Octanoate acts by inhibiting photosystem II (PSII) in the photosynthetic pathway, disrupting electron transport and generating reactive oxygen species that damage plant cells. As a contact herbicide, it only affects the plant tissue it touches and does not translocate throughout the plant.

Uses and Applications:

1. Target Weeds:

   • Annual broadleaf weeds such as Amaranthus spp., Chenopodium spp., Polygonum spp., and Sinapis arvensis (wild mustard).

2. Crops:

   • Wheat, barley, oats

   • Corn (maize)

   • Pasture and rangeland

3. Application Timing:

   • Post-emergence: Apply when weeds are young and actively growing (2–4 leaf stage).

Benefits:

• Fast Action: Rapid visible effects within a few days.

• Selective: Safe for cereals and corn at labeled rates.

• Resistance Management: Effective against weeds resistant to auxin-type herbicides (e.g., 2,4-D).

• Ester Form Advantage: Enhanced leaf penetration for better control.

Limitations:

• Contact Only: Limited control on larger weeds or perennials due to lack of systemic activity.

• Environmental Sensitivity: Degraded by high pH water; use pH-adjusted spray solutions.

• Temperature Dependence: Reduced efficacy in cool or cloudy weather.

• Crop Safety: May cause temporary leaf spotting under stress conditions.

Recommended Application:

• Dosage: 0.25–0.5 kg active ingredient per hectare, depending on crop and weed density.

• Method:

  • Foliar spray with calibrated equipment to ensure full weed coverage.

  • Avoid overlapping or excessive spray concentrations.

• Precautions:

  • Do not apply during periods of crop stress (e.g., drought, frost).

  • Avoid drift onto sensitive broadleaf crops.

Storage and Handling:

• Storage: Keep in tightly sealed containers, away from sunlight and heat.

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

• Safety: Moderate acute toxicity; wear protective clothing, gloves, and avoid inhalation.

FAQ on Bromoxynil Octanoate:

Q1: Does Bromoxynil Octanoate control grasses?
A1: No, it is effective only against broadleaf weeds and has no activity on grasses.

Q2: Can it be tank-mixed with other herbicides?
A2: Yes, it is often mixed with phenoxy herbicides (e.g., MCPA) to broaden weed control spectrum.

Q3: Is it systemic or contact-only?
A3: It is a contact herbicide and does not translocate within the plant.

Q4: What weather conditions improve efficacy?
A4: Warm, sunny conditions enhance herbicide uptake and speed up visible results.