Benfluralin: A Pre-Emergence Herbicide for Annual Grass and Broadleaf Weed Control

Technical Introduction

Benfluralin (IUPAC: N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)aniline) is a selective pre-emergence herbicide from the dinitroaniline chemical family.

It acts by inhibiting microtubule assembly during cell division (mitosis), preventing root and shoot development of germinating weed seeds. Benfluralin is not systemic and remains primarily in the soil near the application site.

• Mode of Action: Microtubule assembly inhibitor (HRAC Group K1 / WSSA Group 3).

• Application Timing: Pre-plant incorporated or pre-emergence before weed germination.

• Absorption: Taken up by emerging roots and shoots of germinating weeds.

Applications

• Crops:

  • Ornamentals (flower beds, nurseries, turfgrass)

  • Vegetables (carrot, lettuce, cole crops)

  • Oilseed crops (flax, canola)

  • Some fruit and nut orchards

• Weeds Controlled:

  • Annual grasses: Setaria spp. (foxtails), Echinochloa crus-galli (barnyardgrass), Digitaria sanguinalis (crabgrass), Lolium spp. (ryegrass)

  • Small-seeded broadleaf weeds: Amaranthus spp., Chenopodium spp., Polygonum spp.

  • Ineffective on established perennial weeds or large-seeded broadleaf species.

Advantages

• Effective Residual Control: Provides several weeks to months of weed suppression.

• Soil-Active: Remains in the top soil layer, targeting germinating weed seeds.

• Crop Selectivity: Safe for many ornamentals and specialty crops.

• Resistance Management: Useful alternative to triazines and other herbicide classes.

• Low Leaching Risk: Strong soil binding reduces groundwater contamination potential.

Specifications (Typical Parameters)

FAQ

Q1: What is Benfluralin mainly used for?
A: It is widely used in ornamentals, turf, and specialty crops to control annual grasses and small-seeded broadleaf weeds before they emerge.

Q2: Does Benfluralin control perennial weeds?
A: No, it only controls annual grasses and some small-seeded broadleaf species; established perennials are unaffected.

Q3: How is Benfluralin applied?
A: It is applied to the soil pre-emergence and often incorporated mechanically or by irrigation to improve placement and activation.

Q4: What is the residual activity of Benfluralin?
A: It typically provides 4–10 weeks of weed control, depending on soil type, rainfall, and crop system.

Q5: Is resistance a concern?
A: Yes, some grass weeds (Lolium rigidum, Eleusine indica) have developed resistance to dinitroaniline herbicides, including Benfluralin. Rotating herbicide modes of action is essential.

Q6: How safe is Benfluralin to crops?
A: It is selective to many broadleaf crops and ornamentals, but crop injury may occur if misapplied or not properly incorporated.