Common Name

Sulfentrazone

 

IUPAC

2′,4′-dichloro-5′-(4-difluoromethyl-4,5-dihydro-3-methyl-5-oxo-1 H -1,2,4-triazol-1-yl)methanesulfonanilide

 

CAS

N -[2,4-dichloro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1 H -1,2,4-triazol-1-yl]phenyl]methanesulfonamide

 

CAS No.

122836-35-5

 

Molecular Formula

C ₁₁ H ₁₀ Cl ₂ F ₂ N ₄ O ₃ S

General Product Information

 

 

Category

Herbicides > Triazolone herbicides
Herbicides > Anilide herbicides
Herbicides > Amide herbicides

 

Activity

Herbicide

Sulfentrazone is applied pre-plant incorporated, early pre-plant (up to 30 days before planting) or pre-emergence. It is absorbed mainly by the plant roots and susceptible plants die after emergence and exposure to light. Sulfentrazone requires moisture present in the soil or as rainfall to reach its full potential as a pre-emergence herbicide. Foliar contact results in rapid dessication and necrosis of exposed plant tissue.

Sulfentrazone provides season-long control of target weeds and the spectrum can be enlarged by tank mixture with other residual herbicides. Sulfentrazone has not shown any cross-resistance with other residual herbicides. DuPont recommended the use of sulfentrazone in a soybean programme consisting of a pre-emergence application of Authority followed by a post-emergence pass with a mixture of glyphosate and Classic (chlorimuron).

Burndown activity is observed for certain broadleaf species (less than 3") and the spectrum can be extended by tank-mixtures with paraquat, glyphosate, 2,4-D, quizalopfop or metribuzin.

There is no rotational restriction for recropping with soybeans or tobacco following application of sulfentrazone. Wheat, barley, oats, rye and triticale have a recropping interval of 4 months and rice, field corn and sorghum can be planted after 10 months. Sugar beet and canola must not be replanted within 30 months.

Field trials conducted over two years in the US demonstrated that sulfentrazone, applied at 140 g ai/ha to sugar cane, provided good control (87-100%) of red morningglory ( Ipomoea coccinea ). Control was superior to the commercial references (atrazine, diuron, terbacil, metribuzin). The applications were made underneath the crop canopy in May to June and followed layby cultivation. Slight discoloration was observed on the sugar cane foliage but the plants recovered rapidly (Weed Technology, 2002).

Field and greenhouse trials have investigated the effectiveness of sulfentrazone, both alone and in combination with S-metolachlor, as a pre-emergence herbicide for broadleaf weed control in potato. Over the dose range tested (0.14 to 0.28 kg/ha), sulfentrazone is reported to provide excellent control of broadleaf weeds, but for grasses the degree of control is rate dependent and is improved by combination with S-metolachlor. Weed control and total yield was found to be comparable with flumioxazin (W0043), metribuzin and rimsulfuron (W0011L). Sulfentrazone was found to produce initial phytotoxicity to Sangre and Chipeta when used at high rates but did not affect the yield, whilst there were no adverse effects with flumioxazin. When used at the lowest rate, sulfentrazone reduced the biomass of hairy nightshade, redroot pigweed, kochia, common lambsquarters and redstem filaree by more than 90%. In a separate study, sulfentrazone was applied pre-emergence or at emergence of the potato plant so that the product would come into contact with the foliage, simulating a delayed pre-application. Excessive injury (60 to 86%) and a reduction of potato height and alterations in potato flowering was observed on emergence application; when sulfentrazone was applied at emergence with metolachlor, the total potato yield was reduced and there were changes in the grade distribution of the potatoes (A-, B- and extra large size). However, at both application timings, control of common lambsquarters was at least 98% even at the lowest rates, which is greater than that provided by metribuzin or metolachlor alone. At the higher application rate of 0.28 kg/ha, goosegrass and large crabgrass were controlled, but common ragweed by only 58%.

The effectiveness of sulfentrazone as a herbicide for strawberries was evaluated in Oregon (USA). Sulfentrazone was applied in May at rates of 140 and 280 g ai/ha, and at 140 g ai/ha with fluamide (280 g ai/ha). The herbicide was found to provide excellent control of broadleaf weeds through early July and August. However, when used alone, sulfentrazone provided little control of grasses, but was effective in combination with fluamide. There were no signs of phytotoxicity. Application in October at 140 g ai/ha was found to provide excellent overall weed control (predominantly annual bluegrass, common groundsel and pineappleweed) through May of the following year. The timing of application did not affect yield and fruit size.

 

CropUse

CropUses:  
Chickpeas, cowpeas, dry peas, horseradish, lima beans, pineapples, soybeans, strawberries, sugar cane, sunflowers, tobacco, turf  
 

 

Premix

Chlorsulfuron+sulfentrazone+sulfometuron-methyl
Chlorimuron-ethyl+sulfentrazone
Sulfentrazone+S-metolachlor
penoxsulam+sulfentrazone+2,4-D+dicamba
Aqueous flowable, dry granule, wettable powder. Premix Parters:   Bacillus thuringiensis   spp.   kurstaki ; carbendazim; chlorothalonil; copper oxychloride; copper oxychloride copper sulfate, basic; copper oxychloride sulfate; copper sulfate, tribasic; cyproconazole; myclobutanil; naphthalene; penconazole; pheromone; pyridaben; tetraconazole; triadimenol; zineb;
 

 

Physical & Safety Data

 

 

Physical Properties

Molecular weight:387.2; Physical form:Tan solid. Density:1.21 g/ml (20 °C); Melting point:121-123 °C; Vapour pressure:1.3 × 10-4 mPa (25 °C); Partition coefficient(n-octanol and water):logP = 1.48; Solubility:In water 0.11 ( pH 6), 0.78 ( pH 7), 16 ( pH 7.5) (all in mg/g, 25 °C). Soluble, to some extent, in acetone and other polar organic solvents.; Stability:Stable to hydrolysis. Readily photolysed in water.;

 

Toxicology

Oral:Acute oral LD ₅₀   for rats 2855 mg/kg. Percutaneous:Acute percutaneous LD ₅₀   for rabbits >2000 mg/kg. Non-irritating to skin; mild eye irritant (rabbits). Non-sensitising to skin (guinea pigs). Inhalation: LC ₅₀   (4 h) for rats >4.14 mg/l. ADI:0.005 mg/kg.

 

Environmental Profile

Ecotoxicology:?
Birds:Acute oral LD ₅₀   for mallard ducks >2250 mg/kg. Dietary LC ₅₀   (8 d) for ducks and quail >5620 mg/kg.Daphnia: LC ₅₀   (48 h) 60.4 mg/l.Fish: LC ₅₀   (96 h) for bluegill sunfish 93.8, rainbow trout >130 mg/l.?

Environmental fate:?
Animals:In rats, nearly all of administered sulfentrazone is excreted in the urine within 72 h.Soil:Stable in soil ( DT ₅₀   18 mo). In water, stable to hydrolysis ( pH 5-9), but readily undergoes photolysis ( DT ₅₀   <0.5 d). Low affinity for organic matter ( K Plant:In soya beans, over 95% of the parent sulfentrazone is metabolised to the non-polar, ring-hydroxymethyl analogue within 12 hours.?
 

Fate in soil:  
Sulfentrazone is very stable to photolysis on soil. It has an aerobic half-life of 1.5 years and an anaerobic half-life of 9 years.
The average value for K _oc   is 43, with a K _d   of less than 1, indicating that sulfentrazone is highly mobile in soil.
Sulfentrazone is degraded by microbial activity; the half-life is 18 months. It is non-volatile.

Fate in aquatic systems:  
Sulfentrazone is chemically stable at pH 5 - 9 but readily undergoes direct photolysis in water with a half-life of less than 12 hours.
Sulfentrazone has a high potential to leach into groundwater under certain conditions and move offsite to surface water. Hence, use on soils with a shallow water table or on sand soils with an organic content of less than 1% is not recommended. The product label also makes clear recommendations to avoid run-off to surface waters.
From an analysis of drinking water exposure, carried out using the EPA′s standard environmental fate models, absorbed aggregate exposure estimates and water data from an FMC Corporation ground water study conducted in North Carolina, the calculated drinking water level of concern was estimated to be 298 ppb for all adults. This is greater than the maximum residue of 42 ppb obtained from the Carolina water-monitoring study. Hence exposure to sulfentrazone in drinking water should not pose a risk to human health.

 

Transport Information

Signal Word:CAUTION; Hazard Class:III(Slightly hazardous)