Benfluralin

Description

Since 1970, benfluralin has been registered in the United States as a preemergent dinitroaniline herbicide. In 2004, the US Environmental Protection Agency (EPA) conducted an assessment to determine if pesticide products containing the active ingredient of benfluralin were eligible for pesticide reregistration. The criteria included meeting current human health and safety standards, and determining if the pesticide being used poses any unreasonable risks to human health and the environment. Results of the US EPA assessment were explained in the Reregistration Eligibility Decision (RED) of benfluralin. The RED document determined that pesticides with the active ingredient of benfluralin were eligible for reregistration provided certain stipulations listed in the RED document were met that included additional label requirements. Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Section 3, all new pesticides used in the United States must be registered by the Administrator of the US EPA. There are 38 products registered for benfluralin.

Chemical Properties

Yellowish-orange crystalline solid. Commercial product is available as an emulsifiable concentrate.

Uses

A trifluoromethyl dinitroaniline selective preemergence herbicide for control of annual grasses and some broad-leaved weeds in vegetables and turf.

Uses

A dinitroanilie heribicide used for the control of a wide range annual grass and broadleaf weeds in crops such as groundnuts, tobacco, lettuce, turf, alfalfa, clover, watermelons and sweet melons.

Uses

Benfluralin is a preemergent herbicide registered to control monocot (one cotyledon: plant embryo with single ‘seed leaf’) and dicot (two cotyledon: plant embryo with two ‘seed leaves’) weeded species in commercial and residential applications. Target species for benfluralin include Johnson grass seedlings, chickweed, lamb quarters, purslane, knotweed, clover, and barnyard grass. Benfluralin affects seed germination and prevents weed growth by inhibition of root development. Absorbed by roots, benfluralin inhibits microtubule formation by binding to tubulin, thereby disrupting cell division and leading to microfibril disorientation. Benfluralin can be used alone or formulated with other structurally related preemergent herbicides. Benfluralin has been formulated with oryzalin, isoxaben, triclopyr and/or trifluralin. Various formulated types include emulsifiable concentrate, granules, soluble concentrate/liquid, and water dispersed granules. Benfluralin is formulated as granules in 42 end-use products and one product in the form of water dispersible granules. Applications can be by broadcast (granules and fertilizer mixed) and band treatment, golf course treatment, soil incorporated treatment, and spray with ground/sprinkler irrigation systems. Agricultural usage of benfluralin is predominately on lettuce, alfalfa, clover, birdsfoot trefoil, nonbearing fruit and nut trees, and vineyards.

Uses

Herbicide.

Definition

ChEBI: A tertiany amino compound that is 2,6-dinitro-4-(trifluoromethyl)aniline in which the hydrogens attached to the aniline nitrogen have been replaced by one ethyl and one butyl group. It is used as a pre-emergence herbicide used for the control of grass and ther weeds in a range of food and non-food crops.

General Description

Yellow-orange solid. Herbicide.

Air & Water Reactions

Slightly water soluble.

Reactivity Profile

A dinitroaniline derivative.

Hazard

Highly toxic.

Agricultural Uses

Herbicide: Selective pre-emergence herbicidal control of annual grasses and broad-leaf weeds. Used on alfalfa, red clover, seeded lettuce, trefoil; peanuts, certain tobaccos, vegetables such as endive, field and French beans and lentils.

Trade name

BALAN®; BALFIN®; BENEFEX®; BETHRODINE®; BHULAN®; BINNELL®; BONALAN®; CARPIDOR®; EL-110®; EMBLEM®; FLUBALEX®; PEL-TECH®; QUILAN®; TEAM; XL 2G Chemical class: 2,6-Dinitroaniline

Potential Exposure

Selective preemergence herbicide used to control of annual grasses and broad-leaf weeds. Used on alfalfa, red clover, seeded lettuce, trefoil; peanuts, certain tobaccos, vegetables such as endive, field and French beans, and lentils. A dinitroaniline derivative.

Environmental Fate

Soil. Benfluralin degraded faster in flooded soils under anaerobic conditions than when oxygen was present. The major route of benfluralin degradation in flooded soil is the formation of polar products (Golab et al., 1970) including N-butyl-N-ethyl-α,α,α-trifluoro- 5-nitrotoluene-3,4-diamine, N-butyl-N-ethyl-α,α,α-trifluorotoluene-3,4,5-triamine, N butyl-N-ethyl-α,α,α-trifluorotoluene-3,4,5-triamine, N-butyl-α,α,α-trifluoro-2,6-dinitro p-toluidine, N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine, N-butyl-α,α,α-trifluoro-5- nitrotoluene-3,4-diamine, N-butyl-α,α,α-trifluorotoluene-3,4,5-triamine, N-ethyl-α,α,α- trifluoro-5-nitrotoluene-3,4-diamine, α,α,α-trifluoro-5-nitrotoluene-3,4-diamine, and α,α,α-trifluorotoluene-3,4,5-triamine (Williams, 1977). The rate of degradation was high est under anaerobic conditions.
Nash (1988) reported a dissipation half-life of 2 days for benfluralin in soil.
Photolytic. Though no products were identified, benfluralin is subject to photodegra dation by UV light (Worthing and Hance, 1991). A photodegradation yield of 79% was achieved after the herbicide in dry soil was subjected to sunlight for 7 days
Chemical/Physical. In aqueous solutions (pH 5–9 and 26°C), benfluralin is stable up to 30 days (Worthing and Hance, 1991).

Shipping

UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9—Miscellaneous hazardous material, Technical Name Required. UN1596 Dinotoanilines, Hazard Class: 6.1; Labels: 6.1—Poisonous materials.

Toxicity evaluation

Use of benfluralin as a preemergent herbicide results in a direct release into the environment. Benfluralin has an estimated Henry’s law constant of 2.91×10-4 atm-m3mol^-1 derived from a vapor pressure of 6.6×105 mmHg. Benfluralin has a water solubility of 0.1 mg l^-1, an octanol/water partition coefficient of Kow = 5.29 and a soil organic carbon– water partitioning coefficient range of Koc= 9840 to 11660. Based on the Henry’s law constant, volatilization of benfluralin from moist soil surfaces and water surfaces is expected. However, volatilization of benfluralin from dry soil surface is not expected. Benfluralin is typically formulated and applied to minimize volatilization. Benfluralin Koc value range indicates a decreased mobility in soil. The Koc value also indicates that benfluralin can be expected to adsorb to suspended solids and sediment in the water column.

Incompatibilities

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Moderate heat causes decomposition that produces toxic vapors that can form an explosive mixture with air.

Waste Disposal

Do not discharge into drains or sewers. Dispose of waste material as hazardous waste using a licensed disposal contractor to an approved landfill. Consult with environmental regulatory agencies for guidance on acceptable disposal practices. If allowed, Incineration with effluent gas scrubbing is recommended. Containers must be disposed of properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office. Ultraviolet-radiation: This liquid herbicide is reported to be susceptible to decomposition by UV radiation.