WO1998035560A1 - Herbicidal composition for use in rice crop - Google Patents

Abstract

This invention relates to α-(2-fluorophenyl)-α-[1-(4-fluorophenyl)ethyl]-1H-1,2,4-triazole-1-ethanol, including a particularly preferred enantiomer, and a method for controlling the growth of undesired vegetation in a rice crop by applying to the locus of the vegetation a herbicidally effective amount of α-(2-fluorophenyl)-α-[1-(4-fluorophenyl)-ethyl]-1H-1,2,4-triazole-1-ethanol. This invention further relates to herbicidal mixtures of α-(2-fluorophenyl)-α-[1-(4-fluorophenyl)ethyl]-1H-1,2,4-triazole-1-ethanol with other herbicides and their use in a rice crop.

Description

TITLE

HERBICIDAL COMPOSITION FOR USE IN RICE CROP

BACKGROUND OF THE INVENTION

The control of undesired vegetation is extremely important in achieving high crop efficiency. Achievement of selective control of the growth of weeds especially in such useful crops as rice, soybean, sugar beet, corn (maize), potato, wheat, barley, tomato and plantation crops, among others, is very desirable. Unchecked weed growth in such useful crops can cause significant reduction in productivity and thereby result in increased costs to the consumer. The control of undesired vegetation in noncrop areas is also important. Many products are commercially available for these purposes, but the need continues for new compounds which are more effective, less costly, less toxic, environmentally safer or have different modes of action.

SUMMARY OF THE INVENTION This invention is directed to a method for controlling the growth of undesirable vegetation in a rice crop comprising applying to the crop after transplantation or emergence of the rice plants an effective amount of a compound of Formula I, including all geometric and stereoisomers, N-oxides, agriculturally suitable salts thereof, as well as mixtures of the aforesaid compounds with certain sulfonylurea herbicides. This invention is also directed to compositions comprising an effective amount of a compound of Formula I including all geometric and stereoisomers, Ν-oxides, agriculturally suitable salts thereof, as well as mixtures of the aforesaid compounds with certain sulfonylurea herbicides and at least one of a surfactant, a solid diluent or a liquid diluent. The invention is also directed to a method for controlling the growth of undesired vegetation in a rice crop by applying the aforesaid compositions to the locus of the rice crop.

(Formula I, α-(2-fluorophenyl)-α-[l -(4-fluorophenyl)ethyl]- 1H- 1 ,2,4-triazole- 1 -ethanol.)

Formula I contains two chiral centers and thus can exist as four stereoisomers. These four stereoisomers consist of two pairs of enantiomers. The enantiomers of each pair are diastereomeric relative to the enantiomers of the other pair. Each pair of enantiomers can be termed an enantiomeric pair. One enantiomeric pair of Formula I has now been discovered to have superior herbicidal utility, and thus the preferred embodiments of the invention include the use of the compounds of Formula I consisting substantially (i.e., at least 85 mol %), or more preferably, essentially (i.e., at least 95 mol %) of this preferred enantiomeric pair for control of undesired vegetation. The preferred enantiomeric pair is distinguished from the other enantiomeric pair on basis of a fingerprint of physical properties.

Furthermore, one enantiomer of said preferred enantiomeric pair has now been discovered to have herbicidal utility not only superior to the other enantiomer, but much superior to that predictable from the activity of the preferred enantiomeric pair. This highly active enantiomer is thus a particularly preferred embodiment of the invention. The highly active enantiomer is distinguished from its less active antipode on basis of the negative [α]jj optical rotation of the highly active enantiomer in trichloromethane solvent compared to the positive [α]j_j optical rotation of the less active enantiomer. Particularly valued are herbicidal compositions comprising a herbicidally effective amount of said highly active enantiomer substantially, or more preferably, essentially free from other isomers and at least one of a surfactant, a solid diluent or a liquid diluent, and the use of said compositions for control of undesired vegetation in rice crops.

The salts of the stereoisomeric compounds of Formula I include acid-addition salts with inorganic or organic acids such as hydrobromic, hydrochloric, nitric, phosphoric, sulfuric, acetic, butyric, fumaric, lactic, maleic, malonic, oxalic, propionic, salicylic, tartaric, 4-toluenesulfonic or valeric acids.

As the agricultural compositions of this invention are used in rice crops, this invention also comprises said compositions as agents for controlling the growth of undesired vegetation in a rice crop, characterized by containing as an active ingredient, a compound of Formula I, geometric and stereoisomers, N-oxides and agriculturally suitable salts thereof.

As a further aspect of this invention, mixtures of α-(2-fiuorophenyl)-α-[l-(4- fluorophenyl)ethyl]-lH-l,2,4-triazole-l-ethanol (the stereoisomeric compounds of Formula I) with certain sulfonylurea herbicides providing selective weed control in rice have been discovered to have a safening effect on rice or a synergistic effect on certain weeds. These herbicidal effects are particularly useful. Preferred embodiments of this aspect of the invention are combinations comprising α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)ethyl]-lH- 1,2,4-triazole-l -ethanol, particularly the aforesaid preferred enantiomeric pair and more particularly the aforesaid highly active enantiomer, with at least one sulfonylurea herbicide selected from the group consisting of bensulfuron methyl, azimsulfuron, metsulfuron methyl, chlorimuron ethyl and pyrazosulfuron ethyl, their herbicidal compositions and their use for selective weed control in rice. Particularly preferred is the combination of α-(2-fluoro- phenyl)-α-[l-(4-fluorophenyl)ethyl]-lH-l,2,4-triazole-l -ethanol with bensulfuron methyl. Also particularly preferred is the combination of α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)- ethyl]- lH-l,2,4-triazole-l -ethanol with a mixture of bensulfuron methyl and azimsulfuron, most preferably where the bensulfuron methyl and azimsulfuron are in about a 5 : 1 ratio, and the combination of α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)ethyl]-lH-l,2,4-triazole-l- ethanol with a mixture of bensulfuron methyl and metsulfuron methyl, most preferably where the bensulfuron methyl and azimsulfuron are in about a 5 : 1 ratio. More preferred are aforesaid mixtures wherein the α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)ethyl]-l /-l,2,4- triazole-1 -ethanol consists substantially (i.e., at least 85 mol %), or more preferably, essentially (i.e., at least 95 mol %) of the aforesaid preferred enantiomeric pair. Most preferred are aforesaid mixtures wherein the α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)ethyl]- lH-l,2,4-triazole-l -ethanol consists substantially, or more preferably, essentially of the aforesaid highly active enantiomer. Particularly valued are herbicidal compositions comprising a herbicidally effective amount of aforesaid mixtures and at least one of a surfactant, a solid diluent or a liquid diluent, and the use of said compositions for control of undesired vegetation in rice.

DETAILS OF THE INVENTION

The compounds of Formula I can be prepared by the following methods as depicted in Schemes 1-5.

The compounds of Formula I can be prepared by reacting the corresponding olefin of Formula 1 with hydrogen in the presence of a suitable heterogeneous catalyst such as palladium, platinum or rhodium on carbon, or a homogeneous catalyst, such as tris(triphenylphosphine)chlororhodium, as outlined in Scheme 1.

Scheme 1

Additional hydrogenation procedures can be found in organic texts, for instance, R. L. Augustine, "Catalytic Hydrogenation," Marcel Dekker, Inc., New York (1965).

The olefin of Formula 1 can be prepared by reacting the oxirane of Formula 2 with 1,2,4-triazole in the presence of its alkali metal salt (preferably the Na⁺ or K⁺ salt) in a suitable solvent such as outlined in Scheme 2. Scheme 2

or Na.)

The oxirane of Formula 2 can be prepared by reacting the corresponding Grignard reagent, made from the bromide of Formula 3, with the phenacyl chloride of Formula 4 as shown in Scheme 3.

Scheme 3

The bromide of Formula 3 can be made by the sequence depicted in Scheme 4 by dehydrohalogenation of the corresponding dibromide of Formula 6, which is made by bromination of l-ethenyl-4-fluorobenzene (5).

Scheme 4

5 6

The phenacyl chloride of Formula 4 can be made by chlorination of commercially available l-(2-fluorophenyl)ethanone (7) shown in Scheme 5.

Scheme 5

Without further elaboration, it is believed that one skilled in the art using the preceding description can utilize the present invention to its fullest extent. The following Examples are, therefore, to be construed as merely illustrative, and not limiting of the disclosure in any way whatsoever. Percentages are by weight except for chromatographic solvent mixtures or where otherwise indicated. Parts and percentages for chromatographic solvent mixtures are by volume unless otherwise indicated. ^lH NMR spectra are reported in ppm downfield from tetramethylsilane; s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet, dd = doublet of doublets, dt = doublet of triplets, br s = broad singlet, AB d = doublet showing "AB" distortion due to coupling to a proton without a large difference in chemical shift. Optical rotations [α] were measured using sodium D-line light and 1 dm-length cells at concentrations specified in units of g of compound per 100 mL of the indicated solvent. EXAMPLE 1

Step A: Preparation of 1 -( 1 ,2-dibromoethyl)-4-fluorobenzene l-Ethenyl-4-fluorobenzene (25 g, 0.201 mol) was dissolved in dichloromethane (500 mL) and cooled to 0 °C. To this solution, a solution of bromine (10.3 g, 0.201 mol) dissolved in dichloromethane (45 mL) was added dropwise over 20 minutes, causing an exotherm. The mixture was stirred at room temperature for 1 hour and then washed with aqueous sodium sulfite solution (0.05 M, 2 x 200 mL). Drying and concentrating yielded the title compound as a white solid (57.5 g, 100% yield) melting 71.5-73.5 °C. *H NMR (CDC1₃) δ 7.3-7.5 (m, 2H), 7.0-7.2 (m, 2H), 5.15 (q, 1H), 4.0-4.2 (d, 2H).

Step B : Preparation of 1 -( 1 -bromoetheny l)-4-fluorobenzene l-(l,2-Dibromoethyl)-4-fluorobenzene was dissolved in a mixture of tetrahydrofuran

(50 mL) and methyl sulfoxide (50 mL). After cooling the solution to 0 °C, aqueous sodium hydroxide (50%, 17.8 mL) was added dropwise, keeping the temperature of the reaction solution below 3 °C. After stirring 30 minutes at this temperature, the green solution was allowed to warm to room temperature and then stirred an additional 3 hours. The mixture was partitioned by adding hexanes (300 mL) and water (60 mL). After removal of the organic phase, the aqueous phase was diluted with water (200 mL), and extracted with hexanes (3 x 100 mL). The hexanes extracts were combined and washed with water (3 x 100 mL) and brine and then dried (MgSO4) and concentrated to leave a yellow oil. Vacuum distillation of the oil afforded a yellow oil (32.3 g, 79.9%) consistent with the desired product, (b.p. 62-63 °C at 0.35 torr (47 Pa)). ^JH NMR (CDC1₃) δ 7.57 (m, 2H), 7.0 (m, 2H), 6.06 (d, 1H), 5.77 (d, 1H).

Step C : Preparation of 2-chloro- 1 -(2-fluorophenyl)ethanone l-(2-Fluorophenyl)ethanone (268.3 g, 2.0 mol) was dissolved in glacial acetic acid

(750 mL) ^"and ^"heated to 35 °C. Chlorine (145 g, 2.04 mol) was condensed and added, using an ice/water cooling bath as necessary to maintain the temperature at 35 °C. After half of the chlorine was added, the temperature was lowered to 30 °C for the remainder of the addition. After 100 minutes, the addition was complete, yielding a colorless solution. This solution was poured into ice-cold water (6 L) and extracted with diethyl ether (2 x 3 L). The combined organic phases were washed with water (3 x 3 L) and then cautiously (because of foaming) with saturated aqueous sodium hydrogen carbonate solution (1 x 1.5 L). The organic phase was then washed with brine (1 x 1 L) and dried (MgSO4). Filtration and evaporation of the solvent left a clear, colorless oil (370 g). Vacuum distillation afforded the title compound as a colorless oil (195 g, 56.5% yield) with a boiling point of 65-66 °C at 0.2 torr (27 Pa). A sample prepared similarly was analyzed by NMR: ^lR NMR (CDC1₃) δ 7.9 (t, 1H), 7.6 (m, 1H), 7.2-7.3 (m, 1H), 7.2 (m, 1H), 4.7 (s, 2H). Step D : Preparation of 2-(2-fluorophenyl)-2- [ 1 -(4-fluorophenyl)ethenyl] oxirane

To a suspension of magnesium (83.7 g, 3.4 mol) in dry tetrahydrofuran (3 L) was added l-(l-bromoethenyl)-4-fluorobenzene first in one portion (50 mL) then by dropwise addition for a total of 738 g (3.28 mol). The dropwise addition was conducted at such a rate as to maintain the temperature at 30-35 °C with cooling using a dry ice/acetone bath as necessary. The addition required 60 minutes; this was followed by stirring at room temperature for another hour to complete preparing the solution of bromo[l-(4- fluorophenyl)ethenyl]magnesium.

In a 22-L Morton flask, 2-chloro-l-(2-fluorophenyl)ethanone (420 g, 2.43 mol) was dissolved in dry tetrahydrofuran (3000 mL) and cooled to -5 °C. The prepared solution of bromo[l-(4-fluorophenyl)ethenyl]magnesium was transferred in portions via cannula to a 1000-mL addition flask and added dropwise to the Morton flask over 1 hour, while maintaining cooling with a dry ice/acetone bath. After the addition was completed, the mixture was stirred overnight at room temperature. The reaction mixture was then cooled to 0 °C, and aqueous ammonium chloride solution (4 M, 2 L) was cautiously added while maintaining cooling. During the first part of the addition, the temperature rose to 20 °C. The mixture was separated, and the aqueous phase was extracted with diethyl ether (2 x 3 L). The combined organic layers were washed with water (2 x 2 L) and brine (2 x 1 L). The organic solution was dried (MgSO,^, and the solvent was evaporated at 50 °C under aspirator vacuum. While maintaining the 50 °C bath, high vacuum was applied for 20 minutes to leave the title compound as a clear, amber oil (567g, 87.5% yield). ^lH NMR (CDC1₃) δ 7.2-7.4 (m, 3H), 6.6-7.0 (m, 4H), 5.35-5.4 (d, 2H), 3.1 (s, 2H).

Step E: Preparation of α-(2-fluorophenyl)- -[l -(4-fluorophenyl)ethenyl]- 1 H- 1 ,2,4- triazole- 1 -ethanol

A solution of lH-l,2,4-triazole (167.8 g, 2.42 mol) and the potassium salt of 1H-1,2,4- triazole (prepared by dissolving potassium tert-butoxide in tetrahydrofuran, treating with \H-

1,2,4-triazole, and filtering the solid thus formed; 104.0 g, 0.97 mol) in methyl sulfoxide (1.5 L) was treated with 2-(2-fluorophenyl)-2-[l-(4-fluorophenyl)ethenyl]oxirane (670 g, 2.6 mol) and heated to 75 °C for 24 hours. The dark red reaction mixture was added over 30 minutes to water (16 L) to produce gummy /tacky solids. After adding sodium chloride (1 kg) the mixture was extracted with ethyl acetate (3 x 4 L). The combined organic layers were washed with water (2 x 6 L) and brine (3 L) and then dried (MgSO^), filtered and concentrated to leave a dark viscous oil (770 g). The oil was dissolved in 2-propanol (8 L), transferred into a 22-L Morton flask, and cooled to 0 °C. Concentrated sulfuric acid (238 g) was added over 20 minutes while keeping the temperature less than 10 °C. Hexanes (1000 mL) was added, followed by seed crystals. (Seed crystals were prepared prior to hexanes addition, by triturating a 100-ml aliquot with a small amount of hexanes and collecting the slowly formed solid.) The crystallizing mixture was stirred at 0-5 °C for about 40 minutes until no more solid formed. The solid was collected by filtration using a coarse-frit funnel, rinsed with diethyl ether (2 x 1 L), and then dried under vacuum with a nitrogen bleed. The light yellow solid (741 g) obtained was then dissolved in a mixture of ethyl acetate (6 L) and water (6 L). The mixture was then carefully neutralized to pH 7.0 by addition of sodium hydrogen carbonate (404 g), accompanied by considerable foaming. The organic layer was removed, washed with water (4 L), and brine (4 L) and dried (MgSO_ι). Filtration, followed by concentration under high vacuum yielded a dark viscous oil (580 g). This oil was warmed to 35 °C and then dissolved in diethyl ether (1.2 L). Once solid began to precipitate, the mixture was cooled to -10 to -12 °C using an ice/acetone bath, and occasionally stirred over 1 hour. Filtration, followed by rinsing with pre-chilled (-30 °C) diethyl ether provided the title compound as a white solid (393 g, 50.0% yield) melting at 93-95 °C. A sample prepared similarly was analyzed by NMR: *H NMR (CDC1₃) δ 7.80 (s, 1H), 7.79 (s, 1H), 7.5 (t, 1H), 7.2-7.3 (m, ~3H after subtracting contribution from CHC1₃ peak), 6.9-7.0 (m, 4H), 5.25-5.30 (dd, 2H), 5.03 (s, 1H), 4.95-5.00 (AB d, 1H), 4.6 (AB d, 1H).

Step F: Preparation of α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)ethyl]-lH- 1,2,4- triazole-1 -ethanol (Compound 1 and Compound 2)

In a Parr shaker apparatus bottle containing palladium-on-carbon catalyst (10%, 0.26 g) suspended in ethanol (50 mL), a solution of α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)- ethenyl]-lH-l,2,4-triazole-l -ethanol (1.3 g, 4 mmol) dissolved in ethanol (20 mL) was added. The bottle was attached to the Parr hydrogenation apparatus, and hydrogen applied at pressure not exceeding 50 psi (344 kPa) with shaking overnight. Filtration through Celite® diatomaceous filter aid, followed by concentration left an oil, which crystallized to a solid melting at 129-134 °C. Column chromatography on silica gel eluting with a 1 :1 mixture of ethyl acetate and hexanes separated the product into two sets of diastereomers (enantiomeric pairs). The first enantiomeric pair to elute (with higher Rf) is designated Compound 1. The second enantiomeric pair to elute (with lower Rf) is designated Compound 2. After evaporation of the chromatography solvent, Compound 1 crystallized as a white solid (0.89 g, 68.5%) yield) melting 137-140 °C. Evaporation of the following chromatography fractions afforded Compound 2 (0.12 g, 9.2% yield). A sample of Compound 1 from a similar preparation was further purified by chromatography on silica gel using 1 :3 then 1:2 ethyl acetate-hexanes as eluant to afford product melting at 139-142 °C. A sample of Compound 2 from a similar preparation melted at 76-78 °C. Compound 1: *H NMR (CDC1₃, 200 MHz) δ 7.71 (s, 1H), 7.69 (s, 1H), 7.5 (m, 3H), 6.9-7.3 (m, 5H), 4.8 (d, 1H), 4.7 (s, 1H), 3.8 (d, 1H), 3.4 (q, 1H), 1.11 (d, 3H). Compound 2: *H NMR (CDC1₃, 200 MHz) δ 7.82 (s, 1H), 7.74 (s, 1H), 6.6-7.1 (m, 8H), 5.0 (d, 1H), 4.65 (s, 1H), 4.6 (d, 1H), 3.4 (q, 1H), 1.54 (d, 3H). (As an alternative to chromatography, Compound 1 can be isolated by triturating with diethyl ether the syrupy oil remaining after concentration following filtration through Celite®.)

Step G: Preparation of (-)-α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)ethyl]-lH-l,2,4- triazole-1 -ethanol (Compound lA) and (+)-α-(2-fluorophenyl)-α-[l-(4- fluorophenyl)ethyl]-lH-l,2,4-triazole-l-ethanol (Compound IB)

The enantiomers comprising the enantiomeric pair racemate Compound 1 were separated using an HPLC system having a 25 cm x 2 cm i.d. Chiralcel OD™ semi- preparative column (Chiral Technologies, Part Number 14045) containing a stationary phase of cellulose tris(3,5-dimethylphenylcarbamate). The eluant employed was a 30:70 mixture of 2-propanol-hexane. The flow rate was 10.0 mL/minute, and the injection volume was 500 μL. A UV detector (235 run) was employed to monitor the separation. The sample solution was prepared in eluent at about 10 mg/mL. After 12 minutes Compound IB was eluted with a measured optical rotation [α]^ +84° (c = 0.025, CHCI3). After 18 minutes Compound 1A was eluted with a measured optical rotation [α]^ -81° (c = 0.10, CHC1₃). Formulation

Compounds of this invention will generally be used as a formulation or composition with an agriculturally suitable carrier comprising at least one of a liquid diluent, a solid diluent or a surfactant. The formulation or composition ingredients are selected to be consistent with the physical properties of the active ingredient, mode of application and environmental factors such as soil type, moisture and temperature. Useful formulations include liquids such as solutions (including emulsifiable concentrates), suspensions, emulsions (including microemulsions and/or suspoemulsions) and the like which optionally can be thickened into gels. Useful formulations further include solids such as dusts, powders, granules, pellets, tablets, films, and the like which can be water-dispersible ("wettable") or water-soluble. Active ingredient can be (micro)encapsulated and further formed into a suspension or solid formulation; alternatively the entire formulation of active ingredient can be encapsulated (or "overcoated"). Encapsulation can control or delay release of the active ingredient. Sprayable formulations can be extended in suitable media and used at spray volumes from about one to several hundred liters per hectare. High-strength compositions are primarily used as intermediates for further formulation.

The formulations will typically contain effective amounts of active ingredient, diluent and surfactant within the following approximate ranges which add up to 100 percent by weight.

Weight Percent

Active

Ingredient Diluent Surfactant

Water-Dispersible and Water-soluble 5-90 0-94 1-15

Granules, Tablets and Powders.

Suspensions, Emulsions, Solutions 5-50 40-95 0-15

(including Emulsifiable

Concentrates)

Dusts 1-25 70-99 0-5

Granules and Pellets 0.01-99 5-99.99 0-15

High Strength Compositions 90-99 0-10 0-2

Typical solid diluents are described in Watkins, et al., Handbook of Insecticide Dust Diluents and Carriers, 2nd Ed., Dorland Books, Caldwell, New Jersey. Typical liquid diluents are described in Marsden, Solvents Guide, 2nd Ed., Interscience, New York, 1950. McCutcheon 's Detergents and Emulsifiers Annual, Allured Publ. Corp., Ridgewood, New Jersey, as well as Sisely and Wood, Encyclopedia of Surface Active Agents, Chemical Publ. Co., Inc., New York, 1964, list surfactants and recommended uses. All formulations can contain minor amounts of additives to reduce foam, caking, corrosion, microbiological growth and the like, or thickeners to increase viscosity. Surfactants include, for example, polyethoxylated alcohols, polyethoxylated alkylphenols, polyethoxylated sorbitan fatty acid esters, dialkyl sulfosuccinates, alkyl sulfates, alkylbenzene sulfonates, organosilicones, N,N-dialkyltaurates, lignin sulfonates, naphthalene sulfonate formaldehyde condensates, polycarboxylates, and polyoxyethylene/polyoxypropylene block copolymers. Solid diluents include, for example, clays such as bentonite, montmorillonite, attapulgite and kaolin, starch, sugar, silica, talc, diatomaceous earth, urea, calcium carbonate, sodium carbonate and bicarbonate, and sodium sulfate. Liquid diluents include, for example, water, N,iV-dimethylformamide, dimethyl sulfoxide, N-alkylpyrrolidone, ethylene glycol, polypropylene glycol, paraffins, alkylbenzenes, alkylnaphthalenes, oils of olive, castor, linseed, tung, sesame, corn, peanut, cottonseed, soybean, rapeseed and coconut, fatty acid esters, ketones such as cyclohexanone, 2-heptanoήe, isophorone and 4-hydroxy-4-methyl-2-pentanone, and alcohols such as methanol, cyclohexanol, decanol and tetrahydrofurfuryl alcohol. Solutions, including emulsifiable concentrates, can be prepared by simply mixing the ingredients. Dusts and powders can be prepared by blending and, usually, grinding as in a hammer mill or fluid-energy mill. Suspensions are usually prepared by wet-milling; see, for example, U.S. 3,060,084. Granules and pellets can be prepared by spraying the active material upon preformed granular carriers or by agglomeration techniques. See Browning, "Agglomeration", Chemical Engineering, December 4, 1967, pp 147—48, Perry's Chemical Engineer's Handbook, 4th Ed., McGraw-Hill, New York, 1963, pages 8-57 and following, and WO 91/13546. Pellets can be prepared as described in U.S. 4,172,714. Water-dispersible and water-soluble granules can be prepared as taught in U.S. 4,144,050, U.S. 3,920,442 and DE 3,246,493. Tablets can be prepared as taught in U.S. 5,180,587, U.S. 5,232,701 and U.S. 5,208,030. Films can be prepared as taught in GB 2,095,558 and U.S. 3,299,566.

For further information regarding the art of formulation, see U.S. 3,235,361, Col. 6, line 16 through Col. 7, line 19 and Examples 10-41; U.S. 3,309,192, Col. 5, line 43 through Col. 7, line 62 and Examples 8, 12, 15, 39, 41, 52, 53, 58, 132, 138-140, 162-164, 166, 167 and 169-182; U.S. 2,891,855, Col. 3, line 66 through Col. 5, line 17 and Examples 1-4; Klingman, Weed Control as a Science, John Wiley and Sons, Inc., New York, 1961, pp 81- 96; and Hance et al., Weed Control Handbook, 8th Ed., Blackwell Scientific Publications, Oxford, 1989. In the following Examples, all percentages are by weight and all formulations are prepared in conventional ways. Compound numbers refer to compounds described in preparative Example 1, Steps F and G beginning on page 7.

Example A High Strength Concentrate Compound 1 98.5% silica aerogel 0.5% synthetic amorphous fine silica 1.0%.

Example B Wettable Powder Compound 1 65.0% dodecylphenol polyethylene glycol ether 2.0% sodium ligninsulfonate 4.0% sodium silicoaluminate 6.0% montmorillonite (calcined) 23.0%>. Example C Granule

Compound 1 10.0% attapulgite granules (low volatile matter,

0.71/0.30 mm; U.S.S. No. 25-50 sieves) 90.0%.

Example D

Extruded Pellet

Compound 1 25.0% anhydrous sodium sulfate 10.0% crude calcium ligninsulfonate 5.0% sodium alkylnaphthalenesulfonate 1.0% calcium/magnesium bentonite 59.0%,

Example E

Hiεh Strength Concentrate

Compound 1A 98.5% silica aerogel 0.5% synthetic amorphous fine silica 1.0%.

Example F

Wettable Powder

Compound 1A 65.0% dodecylphenol polyethylene glycol ether 2.0% sodium ligninsulfonate 4.0% sodium silicoaluminate 6.0% montmorillonite (calcined) 23.0%.

Example G

High Strength Concentrate

Compound 1 65.7% bensulfuron methyl 32.8% silica aerogel 0.5% synthetic amorphous fine silica 1.0%.

Example H

Wettable Powder

Compound 1A 21.0% bensulfuron methyl 44.0%> dodecylphenol polyethylene glycol ether 2.0%> sodium ligninsulfonate 4.0% sodium silicoaluminate 6.0% montmorillonite (calcined) 23.0%. Example I

Granule

Compound 1 9.0% azimsulfuron 1.0% attapulgite granules (low volatile matter,

0.71/0.30 mm; U.S.S. No. 25-50 sieves) 90.0%.

Example J

Extruded Pellet

Compound 1 24.4% metsulfuron methyl 0.6% anhydrous sodium sulfate 10.0% crude calcium ligninsulfonate 5.0% sodium alkylnaphthalenesulfonate 1.0% calcium/magnesium bentonite 59.0%.

Example K

High Strength Concentrate

Compound 1 96.3% chlorimuron ethyl 2.2% silica aerogel 0.5% synthetic amorphous fine silica 1.0%.

Example L

Wettable Powder

Compound 1A 52.0% azimsulfuron 13.0% dodecylphenol polyethylene glycol ether 2.0% sodium ligninsulfonate 4.0% sodium silicoaluminate 6.0% montmorillonite (calcined) 23.0%.

Example M _ H_ig__h Strength Concentrate

Compound 1A 89.5% metsulfuron methyl 9.0% silica aerogel 0.5% synthetic amorphous fine silica 1.0%. Utility

The stereoisomeric compounds of Formula I are now discovered to have herbicidal activity with selective safety to certain annual monocot plant species such as rice. Of these compounds, the preferred stereoisomeric pair identified as Compound 1 in preparative Example 1 , Step F on page 7 is found to particularly useful for selective control of undesired vegetation in annual crops such as barley, wheat, corn (maize) and rice and perennial plantation crops such as coffee, cocoa, oil palm, rubber, banana, citrus and conifers. Compound 1 is particularly valued for selective weed control in rice crops because of the range of agronomically important weeds controlled with crop safety.

Compound 1 is effective in selectively controlling the growth of undesirable upland and aquatic grass, broadleaf, and sedge weed species while having little or no effect upon transplanted or direct seeded japonica or indica rice. By applying the compound of this invention to dry or flooded soil infested with weed seed, or application to the foliage of weed plants, or application to water covering foliage, seeds or plant parts, sufficient injury occurs to the weeds to provide the rice crop a competitive advantage. Application to direct seeded rice at the preemergence to 4-leaf stage, application to transplanted rice at the 1.0-4.0-leaf stage and application to weeds at the preemergence to 3 -leaf stage is preferable. Application can be made to intermittently or continuous flood rice culture. For selective herbicidal use in rice, the particular amount to be applied will vary depending upon recognized factors such as the target plant, the primary locus, the timing of application, application mode and formulation, the various conditions of treatment such as soil and weather. In general, the desired results of weed control are obtained upon application of Compound 1 at a rate range of 0.001 to 1.0 kg/hectare and preferably 0.05 to 0.25 kg/hectare, with the application being repeated as necessary. Compound 1 A free from other isomers is about three to four times more active than Compound 1, so in general, the desired results of weed control are obtained upon application of Compound 1A at a rate range of 0.0003 to 0.3 kg/hectare and preferably 0.0125 to 0.08 kg/hectare, with the application being repeated as necessary. The lower application rates in these ranges are particularly useful when Compounds 1 and 1A are used in combination with other herbicides. One skilled in the art can easily determine the herbicidally effective amount necessary for the desired level of weed control. As the non-preferred stereoisomeric pair (Compound 2) has much less herbicidal activity, applications of Formula I stereoisomeric mixtures containing Compound 2 as well as Compound 1 require corresponding greater application rates to obtain sufficient herbicidal efficacy.

For practical use as a herbicide, the compounds of Formula I may be employed in mixture with other known herbicides and agricultural crop protection chemicals to provide additional spectrum of activity against additional weed species. Herbicides which may be mixed include, but are not limited to, cyhalofop-butyl, dimepiperate, thiobencarb, pyributicarb, mefenacet, anilofos and benfuresate. Particularly useful herbicide mixture partners are the sulfonylurea herbicides bensulfuron methyl, azimsulfuron, metsulfuron methyl, chlorimuron ethyl and pyrazosulfuron ethyl, imazosulfuron, cinosulfuron and cyclosulfamuron. Mixtures of α-(2-fluorophenyl)-α- [ 1 -(4-fluoropheny l)ethy 1 ] - 1 H- 1 ,2 ,4-triazole- 1 - ethanol (the stereoisomeric compounds of Formula I) with certain of these sulfonylurea herbicides have been discovered to have a safening effect on rice, while retaining an additive or even a synergistic effect on certain weeds. Particularly useful are combinations comprising α-(2-fluorophenyl)-α- [ 1 -(4-fluoropheny l)ethyl] - 1 H- 1 ,2 ,4-triazole- 1 -ethanol, preferably the aforesaid preferred enantiomeric pair (Compound 1) or the aforesaid highly active enantiomer (Compound 1A), with bensulfuron methyl. These combinations have a surprising safening effect on rice, while retaining weed control efficacy and for some weeds showing synergy. The preferred enantiomeric pair of Formula I (Compound 1) is used in a ratio to bensulfuron methyl in the general range of about 1:15 to 100:1, preferably in the range of about 1 :5 to 10:1. In these mixtures, Compound 1 is generally applied at a rate of at least about 10 g a.i./ha together with at least about 10 g a.i./ha of bensulfuron methyl, and the Compound 1 is generally applied at a rate of no more than about 1000 g a.i./ha together with no more than about 150 g a.i./ha of bensulfuron methyl. For typical use of these mixtures for selective weed control in rice cultivation, Compound 1 is applied at a rate of at least about 50 g a.i./ha together with at least about 25 g a.i./ha of bensulfuron methyl, and Compound 1 is applied at a rate of no more than about 250 g a.i./ha together with no more than about 100 g a.i./ha of bensulfuron methyl. As Compound 1 A is about three to four times more active than Compound 1, correspondingly less is applied in these mixtures with bensulfuron methyl. Additional herbicidal active ingredients can be used in combination with the α-(2- fluorophenyl)-α-[l-(4-fluorophenyl)ethyl]-lH-l ,2,4-triazole-l -ethanol and bensulfuron methyl. Particularly useful are combinations comprising also azimsulfuron as an additional active component, preferably in a ratio of about 1 :5 to bensulfuron methyl.

Also useful are mixtures of α-(2-fluorophenyl)-α-[l-(4-fluorophenyl)ethyl]-lH-l,2,4- triazole-1 -ethanol, preferably the aforesaid preferred enantiomeric pair (Compound 1) or the aforesaid highly active enantiomer (Compound 1A), with azimsulfuron alone or in combination with other herbicides, with metsulfuron methyl alone or in combination with other herbicides, particularly bensulfuron methyl in about a 1:5 ratio of metsulfuron methyl with bensulfuron methyl, or with chlorimuron ethyl alone or in combination with other herbicides, particularly metsulfuron methyl in about a 1:1 ratio of chlorimuron to metsulfuron methyl. These mixtures afford safening to rice or synergism on certain weeds.

The preferred enantiomeric pair of Formula I (Compound 1) is used in a ratio to azimsulfuron in the general range of about 330:1 to 1:5, preferably in the range of about 50:1 to 2:1. In these mixtures, Compound 1 is generally applied at a rate of at least about 10 g a.i./ha together with at least about 3 g a.i./ha of azimsulfuron, and the Compound 1 is generally applied at a rate of no more than about 1000 g a.i./ha together with no more than about 50 g a.i./ha of azimsulfuron. For typical use of these mixtures for selective weed control in rice cultivation, Compound 1 is applied at a rate of at least about 50 g a.i./ha together with at least about 5 g a.i./ha of azimsulfuron, and Compound 1 is applied at a rate of no more than about 250 g a.i./ha together with no more than about 25 g a.i./ha of azimsulfuron. As Compound 1A is about three to four times more active than Compound 1, correspondingly less is applied in these mixtures with azimsulfuron. The preferred enantiomeric pair of Formula I (Compound 1) is used in a ratio to metsulfuron methyl in the general range of about 2000:1 to 1:1, preferably in the range of about 250:1 to 8:1. In these mixtures, Compound 1 is generally applied at a rate of at least about 10 g a.i./ha together with at least about 0.5 g a.i./ha of metsulfuron methyl, and the Compound 1 is generally applied at a rate of no more than about 1000 g a.i./ha together with no more than about 10 g a.i./ha of metsulfuron methyl. For typical use of these mixtures for selective weed control in rice cultivation, Compound 1 is applied at a rate of at least about 50 g a.i./ha together with at least about 1 g a.i./ha of metsulfuron methyl, and Compound 1 is applied at a rate of no more than about 250 g a.i./ha together with no more than about 6 g a.i./ha of metsulfuron methyl. As Compound 1 A is about three to four times more active than Compound 1, one-third to one-quarter as much is applied in these mixtures with metsulfuron methyl.

The preferred enantiomeric pair of Formula I (Compound 1) is used in a ratio to chlorimuron ethyl in the general range of about 4000:1 to 1:1, preferably in the range of about 250:1 to 8:1. In these mixtures, Compound 1 is generally applied at a rate of at least about 10 g a.i./ha together with at least about 0.25 g a.i./ha of chlorimuron ethyl, and the Compound 1 is generally applied at a rate of no more than about 1000 g a.i./ha together with no more than about 10 g a.i./ha of chlorimuron ethyl. For typical use of these mixtures for selective weed control in rice cultivation, Compound 1 is applied at a rate of at least about 50 g a.i./ha together with at least about 1 g a.i./ha of chlorimuron ethyl, and Compound 1 is applied at a rate of no more than about 250 g a.i./ha together with no more than about 6 g a.i./ha of chlorimuron ethyl. As Compound 1A is about three to four times more active than Compound 1, one-third to one-quarter as much is applied in these mixtures with chlorimuron ethyl.

Additionally, these compounds may be combined with agriculturally acceptable additives such as surfactants, safeners, spreaders, emulsifiers or fertilizers, to improve performance. The compounds of Formula I will generally be used as formulated compositions.

The following Tests demonstrate the control efficacy of the compounds of this invention against specific weeds. The weed control afforded by the compounds is not limited, however, to these species. See preparative Example 1, Steps F and G beginning on page 7 for compound preparation and characterization. Compound 1 is the preferred enantiomeric pair of Formula I having superior herbicidal utility. Compound 2 is the other enantiomeric pair of Formula I. Compound 1A is the highly active enantiomer of the preferred enantiomeric pair and has a negative [a]rj> optical rotation. Compound IB is the less active enantiomer of the preferred enantiomeric pair and has a positive [a]_, optical rotation.

BIOLOGICAL EXAMPLES OF THE INVENTION TEST A

Seeds of barley (Hordeum vulgare), barnyardgrass (Echinochloa crus-gallϊ), bedstraw (Galium aparine), blackgrass (Alopecurus myosuroides), chickweed (Stellaria media), cocklebur (Xanthium strumarium), corn (Zea mays), cotton (Gossypium hirsutum), crabgrass (Digitaria sanguinalis), cheatgrass (Bromus secalinus) or downy brome (Bromus tectorum), giant foxtail (Setaria faberii), lambsquarters (Chenopodium album), momingglory (Ipomoea hederacea), rape (Brassica napus), rice (Oryza sativa), sorghum (Sorghum bicolor), soybean (Glycine max), sugar beet (Beta vulgaris), velvetleaf (Abutilon theophrasti), wheat (Triticum aestivum), wild buckwheat (Polygonum convolvulus), wild oat (Avena fatua) and purple nutsedge (Cyperus rotundus) tubers were planted in soil and treated preemergence (pre) with the test compounds formulated in a non-phytotoxic solvent mixture which includes a surfactant.

At the same time, these crop and weed species were also treated with postemergence (post) applications of the test compounds formulated in the same manner. Plants ranged in height from two to eighteen cm (one- to four-leaf stage) for postemergence treatments. Treated plants and controls were maintained in a greenhouse for twelve to sixteen days, after which all species were compared to controls and visually evaluated. Plant response ratings, summarized in Table A, are based on a scale of 0 to 10 where 0 is no effect and 10 is complete control. A dash (-) response means no test result.

Table A - Herbicidal Effect of Compounds 1 and 2

Compound 1 Compound 2

Postemergence Preemergence Post Pre

Application Rate (g/ha) 400 100 400 100 400 400

Barley 4 4 0 0 0 0

Barnyardgrass 9 1 9 0 0 0

Bedstraw 9 8 0 0 - -

Blackgrass 2 0 0 0 - -

Cheatgrass - - - - 0 0

Chickweed 4 0 3 0 - -

Cocklebur 5 4 2 0 2 2

Com 1 0 0 0 2 5

Cotton 8 3 8 0 2 0

Crabgrass 9 9 9 9 0 5

Downy brome 0 0 0 0 - -

Giant foxtail 9 8 9 9 2 9

Lambsquarters 7 5 9 8 - -

Momingglory 10 5 9 0 8 0

Nutsedge 2 0 9 0 0 0

Rape 6 3 3 2 - -

Rice 2 0 0 0 0 0

Sorghum 0 0 2 0 0 0

Soybean 9 4 9 0 8 0

Sugar beet 9 7 8 3 2 3

Velvetleaf 8 3 8 3 0 0

Wheat 2 0 0 0 0 0

Wild buckwheat 8 7 0 0 - -

Wild oat 0 0 0 0 0 0

Table A shows Compound 1 and Compound 2 both have herbicidal effects with relative safety to rice and some other annual monocot crops such as wheat, barley and com (maize). Compound 1 is seen to be generally much more herbicidally active than Compound

2.

TEST B

Compound 1 evaluated in this test was formulated in a non-phytotoxic solvent mixture which includes a surfactant and applied to the soil surface before plant seedlings emerged (preemergence application), to water that covered the soil surface (flood application), and to plants that were in the one-to-four leaf stage (postemergence application). A sandy loam soil was used for the preemergence and postemergence tests, while a silt loam soil was used in the flood test. Water depth was approximately 2.5 cm for the flood test and was maintained at this level for the duration of the test.

Plant species in the preemergence and postemergence tests consisted of bamyardgrass (Echinochloa crus-galli), barley (Hordeum vulgare), bedstraw (Galium aparine), blackgrass (Alopecurus myosuroides), chickweed (Stellaria media), cocklebur (Xanthium strumarium), com (Zea mays), cotton (Gossypium hirsutum), crabgrass (Digitaria sanguinalis), downy brome (Bromus tectorum), giant foxtail (Setaria faberii), green foxtail (Setaria viridus), jimsonweed (Datura stramonium) johnsongrass (Sorghum halpense), lambsquarters (Chenopodium album), momingglory (Ipomoea hederacea), nutsedge (Cyperus rotundus), redroot pigweed (Amaranthus retroflexus), rape (Brassica napus), drill-seeded rice (Oryza sativa, Japonica variety; "drill-seeded" means seeds planted in the soil), Italian ryegrass (Lolium multiflorum), sicklepod (Cassia obtusifolia), soybean (Glycine max), speedwell (Veronica persicd), sugar beet (Beta vulgaris), teaweed (Sida spinosa) velvetleaf (Abutilon theophrasti), wheat (Triticum aestivum), wild buckwheat (Polygonum convolvulus), and wild oat (Avena fatua). All plant species were planted one day before application of the compound for the preemergence portion of this test. Plantings of these species were adjusted to produce plants of appropriate size for the postemergence portion of the test. Plant species in the flood test consisted of transplanted rice (Oryza sativa, Japonica variety), umbrella sedge (Cyperus difformis), duck salad (Heteranthera limosa), bamyardgrass (Echinochloa crus-galli) and late watergrass (Echinocloa oryzicola) grown to the 2-leaf stage for testing.

All plant species were grown using normal greenhouse practices. Visual evaluations of injury expressed on treated plants, when compared to untreated controls, were recorded approximately fourteen to twenty one days after application of the test compound. Plant response ratings, summarized in Table B, were recorded on a 0 to 100 scale where 0 is no effect and 100 is complete control. A dash (-) response means no test result.

Table B - Effect of Compound 1 on Crops and Weeds

Postemergence ] Preemer gence

Application Rate (g/ha) 500 250 125 62 500 250 125 62

Barley 10 10 0 0 10 0 0 0

Bamyardgrass 90 50 30 0 100 100 30 0

Bamyardgrass (flood test) 85 75 65 35 - - - -

Bedstraw 70 60 60 50 90 80 80 70

Blackgrass 50 30 0 0 70 30 0 0

Chickweed 70 30 10 10 70 50 30 0

Cocklebur 30 0 50 30 50 0 0 0

Com 50 0 0 0 20 0 0 0

Cotton 90 60 40 30 70 40 0 0

Crabgrass 100 90 60 60 100 100 100 0

Downy brome 30 0 0 0 0 0 0 0

Duck salad 100 100 100 20 - - - -

Giant foxtail 90 80 10 10 100 100 90 30

Green foxtail 90 80 - - 100 100 100 30

Italian ryegrass 35 20 20 10 50 0 0 0

Jimsonweed 90 70 - - 80 50 30 20

Johnsongrass 90 70 25 10 100 90 30 0

Lambsquarters 100 100 40 35 100 100 70 60

Late watergrass 85 85 70 35 - - - -

Momingglory 100 100 75 35 90 80 30 0

Nutsedge 100 30 - - 50 30 0 0

Rape 70 60 20 10 70 50 30 0

Redroot pigweed 55 50 40 30 90 90 90 85

Rice (drill-seeded) 0 0 - - 0 0 0 0

Rice (transplanted, flood test) 60 35 20 10 - - - -

Sicklepod 70 50 - - 90 40 20 0

Soybean 60 30 40 35 80 70 0 0

Speedwell 90 90 90 90 50 40 30 0

Sugar beet 80 70 15 10 70 60 30 0

Teaweed 100 100 - - 80 40 20 0

Umbrella sedge 90 90 90 90 - - - -

Velvetleaf 90 70 30 10 90 80 40 0

Wheat 0 0 0 0 0 0 0 0

Wild buckwheat 90 70 80 60 70 60 50 30

Wild oat 0 0 0 0 0 0 0 0 Table B again illustrates weed control efficacy of Compound 1 with relative safety to rice and some other annual monocot crops such as wheat, barley and com (maize). The safety to rice and wheat is particularly notable.

TEST C Plastic pots were partially filled with silt loam soil. The soil was then saturated with water. Rice (Oryza sativa) Indica and Japonica seedlings at the 2.0- to 3.0-leaf stage transplanted at 2-cm soil depth; seeds, tubers or plant parts selected from ducksalad (Heteranthera limosa), early watergrass (Echinochloa oryzoides), late watergrass (Echinochloa oryzicola), redstem (Ammania species), rice flatsedge (Cyperus iria), smallflower flatsedge (Cyperus difformis) and tighthead sprangletop (Leptochloa fasicularis) were planted into this soil. Plantings and waterings of these crops and weed species were adjusted to produce plants of appropriate size for the test. At the two-leaf stage of the weeds, water levels were raised to 3 cm above the soil surface and maintained at this level throughout the test. Compound 1 was formulated in a non-phytotoxic solvent mixture which includes a surfactant and applied directly to the paddy water, by pipette, or to the plant foliage, by an air-pressure assisted, calibrated belt-conveyer spray system.

Treated plants and controls were maintained in a greenhouse for approximately 21 days, after which all species were compared to controls and visually evaluated. Plant response ratings, summarized in Table C, are reported on a 0 to 100 scale where 0 is no effect and 100 is complete control. A dash (-) response means no test result.

Table C - Effect of Compound 1 on Rice and Weeds in Greenhouse Test

Application Rate (g/ha ) 500 250 125 64 32

Ducksalad 100 100 100 100 90

Early watergrass 100 80 50 40 20

Late watergrass 100 90 85 45 0

Redstem 100 100 100 100 100

Rice flatsedge 100 100 100 100 100

Smallflower flatsedge - 100 100 100 100

Tighthead sprang ;letop 100 100 100 98 60

Rice (Indica) 85 70 50 40 15

Rice (Japonica) 100 90 50 40 15

The results listed in Table C show Compound 1 providing excellent control of ducksalad, redstem, rice flatsedge, smallflower flatsedge and tighthead sprangletop at 32-

125 g/ha application rates causing only moderate injury to rice. As rice is much more tender and susceptible to herbicide injury when grown in a greenhouse rather than outdoors, little crop injury would be expected at application rates as high as 125 g/ha under field conditions. This is confirmed by Test F below (see page 23).

TEST D

Seeds, tubers, or plant parts of alexandergrass (Brachiaria plantaginea), alfalfa (Medicago sativa), bermudagrass (Cynodon dactyloή), broadleaf signalgrass (Brachiaria plantyphylla), common purslane (Portulaca oleracea), common ragweed (Ambrosia elatior), dallisgrass (Paspalum dilatatum), goosegrass (Eleusine indica), guineagrass (Panicum maximum), itchgrass (Rottboellia exaltata), johnsongrass (Sorghum halepense), large crabgrass (Digitaria sanguinalis), peanuts (Arachis hypogaea), pitted momingglory (Ipomoea lacunosa), purple nutsedge (Cyperus rotundus), sandbur (Cenchrus echinatus), sourgrass (Trichachne insularis) and Texas panicum (Panicum texanum) were planted into greenhouse pots of flats containing greenhouse planting medium. (These weeds are agronomically important in perennial plantation crops such as coffee, cocoa, oil palm, rubber, banana, citrus and conifers.) Plant species were grown in separate pots or individual compartments. Preemergence applications were made within one day of planting the seed or plant part. Postemergence applications were applied when the plants were in the two to four leaf stage (3 to 20 cm).

Compound 1 was formulated in a non-phytotoxic solvent mixture which included a surfactant and applied preemergence and postemergence to the plants. Untreated control plants and treated plants were placed in the greenhouse and visually evaluated for injury 13 to 21 days after herbicide application. Plant response ratings, summarized in Table D, are based on a 0 to 100 scale where 0 is no injury and 100 is complete control.

Table D - Effect of Compound 1 on Weeds Agronomically Important in Plantation Crops Postemergence (Post) and Preemergence (Pre) at 250 g/ha Application Rate

Alexandergrass

Alfalfa

Bermudagrass

Broadleaf signalgrass

Common purslane

Common ragweed

Dallisgrass

Goosegrass

Guineagrass

The results listed in Table D show Compound 1 is efficacious in controlling preemergence many of the weeds which are troublesome in perennial plantation crops. TEST E

Individual containers of bamyardgrass (Echinochloa oryzicola), small flower umbrella sedge (Cyperus difformis), common falsepimpemel (Lindernia procumbens), monochoria (Monochoria vaginalis) and bulrush (Scirpus juncoides) were seeded and allowed to grow until the 1.5- to 2.5-leaf stage of development. A Saitama clay loam soil was used for this propagation. Rice (Oryza sativa, cv. Nipponbare) was transplanted at 0 and 2 cm depth five days before application of the test compound to the water surface. Compound 1 evaluated in this test were formulated in a non-phytotoxic solvent mixture and applied to the surface of the water which was contained in each pot. An early and late stage of each weed species was treated, the stage of development being related to the concurrent planting of Scirpus juncoides which was then treated at the 1.5 (early) and the 2.5 (late) leaf stage.

Treated plants and untreated controls were maintained under greenhouse conditions for 20 to 30 days at which time treated plants were compared to untreated controls and visually evaluated. Plant response ratings, summarized in Table E, are based upon a 0 to 100 scale where 0 is no effect and 100 is complete control.

Table E - Effect of Compound 1 on Rice and Weeds in Greenhouse Test

Application Rate (g/ha) 500 250 125 64 32 16

Bamyardgrass (early) 100 100 100 100 100 40

Bamyardgrass (late) 100 100 100 100 70 50

Bulrush (early) 90 90 90 90 90 30

Bulrush (late) 90 90 90 90 70 40

Common falsepimpemel (early) 90 90 90 90 80 30

Common falsepimpemel (late) 90 95 90 90 50 50

Monochoria (early) 100 100 100 100 100 100

Monochoria (late) 100 100 100 100 60 60

Small flower umbella sedge (early) 95 90 95 90 90 80

Small flower umbella sedge (late) 95 100 90 100 100 90

Rice (0-cm) 100 95 95 85 40 25

Rice (2-cm) 40 60 0 25 0 10

As can be seen from the results listed in Table E, rice is much less susceptible to injury from Compound 1 when it is transplanted to 2 cm depth (as is general rice-farming practice). When transplanted 2-cm deep, rice showed little or no injury at application rates as high as 125 g/ha. As rice is much more tender and susceptible to herbicide injury when grown in a greenhouse rather than outdoors, the greenhouse results suggest no crop injury at application rates as high as 125 g/ha under field conditions. This is confirmed by Test F below. Table E shows 90%) or greater control of all the plant species tested at application rates of 64 g/ha or greater. At these application rates, the leaf-stage of treated plants had little effect on the efficacy of Compound 1.

TEST F

Concrete pots (50 cm x 50 cm; 2.5 ma surface area) were partially filled with non- sterilized clay loam soil containing a 36:44:20 ratio of sand, silt and clay and 1.2% organic matter. The soil was then flooded with water. The same soil mixed with seeds of Echinochloa oryzicola, Monochoria vaginalis, Cyperus difformis, Rotala indica, Lindernia procumbens and Scirpus juncoides was spread in the paddy soil, and then it was puddled. The 2.2-leaf stage of rice seedlings (Oryza sativa, variety Nipponbare) were planted at the depth of 0, 1 and 2 cm. (In actual farming, rice is typically transplanted at 2-cm depth.) For 0 and 1 cm planting, rice seedlings were supported by plastic ties. Tubers of Sagittaria pygmaea, Cyperus serotinus and Eleocharis kuroguwai were planted in the soil. To assess the effect of plant size and age at time of Compound 1 treatment on the herbicidal response, the pots were divided into three groups. The first group (5DAT) was treated 5 days after transplanting the rice. The second group (Eo2.5L) was treated when the Echinochloa oryzicola plants reached the 2.5-leaf stage. The third group (Eo3.0L) was treated when the Echinochloa oryzicola plants reached the 3-leaf stage. At treatment time the water level was raised to 4 cm above the soil surface. Compound 1 was formulated in acetone and applied directly to the paddy water. Paddy water in each concrete pot was leached out of the soil at the hole on the bottom edge at the rate of 7.5 liters per 24 hours for 2 days right after the treatments. The water level was raised to 4 cm after the first 24 hours leaching and was raised to 3 cm when the leaching was finished. Plants and controls were maintained outdoors. Rice and all weed species were compared to controls after 24 and 50 days, respectively, and visually evaluated. Plant response ratings, summarized in Table F, are reported on a 0 to 100 scale where 0 is no effect and 100 is complete control.

Table F - Effect of Compound 1 on Rice and Weeds in Outdoor Test Representative of Field Conditions

Application Timing: 5DAT Eo2.5L Eo3.0L

Application Rate (g/ha): 60 90 60 90 60 90

Crop iniurv

Rice, 0-cm planting 30 45 15 25 25 35

Rice, 1 -cm planting 0 0 0 0 0 0

Rice, 2-cm planting 0 0 0 0 0 0

Weed control

Echinochloa oryzicola 95 100 90 100 80 100

Scirpus juncoides 60 70 45 75 70 90

Cyperus difformis 100 100 100 100 100 100

Lindernia procumbens 70 75 65 85 70 80

Rotala indica 100 100 100 100 100 100

Monochoria vaginalis 100 100 100 100 100 100

Cyperus serotinus 80 80 70 95 55 95

Eleocharis kuroguwai 45 50 40 55 45 55

Sagittaria pygmaea 0 40 0 45 20 30

As can be seen from the results listed in Table F, the leaf-stage of plants does not have a large effect on the efficacy of Compound 1. Compound 1 caused no injury to rice at application rates of 60 and 90 g/ha when the rice was transplanted at 1 or 2-cm depth. (In rice farming, rice is generally transplanted 2 cm deep.) At an application rate of 90 g/ha, Compound 1 completely controlled four of the weeds and had a strong effect on three more. This test, representative of field growing conditions, demonstrates the great utility of Compound 1 for selective weed control in rice farming. TEST G

Wagner pots (0.5 ma surface area) were partially filled with non-sterilized clay loam soil containing a 36:44:20 ratio of sand, silt and clay and 1.2% organic matter. The soil was then flooded with water and puddled, and rice seedlings (Oryza sativa, variety Nipponbare) at the 2.2-leaf stage were planted at depths of 0, 1 and 2 cm. Seeds of Echinochloa oryzicola, Monochoria vaginalis, Cyperus difformis, Lindernia procumbens and Scirpus juncoides were sown and tubers of Sagittaria pygmaea, Cyperus serotinus and Eleocharis kuroguwai were planted in the soil. The rice plants were treated 5 days after transplantation. The weed plants were grown to three different growth stages before treatment. The growth stages treated were identified by the leaf stage of E. orzicola (Eo): 0.5 -leaf stage (5 days after rice transplanting), 2-leaf stage and 2.5-leaf stage. At treatment time, the water level was raised to 4 cm above the soil surface. Chemical treatments were formulated in acetone and applied directly to the paddy water. Paddy water in each Wagner pot was leached out of the soil at the hole on the bottom edge at the rate of 1.5 liters per 24 hours for 2 days immediately following the treatments. The water level was raised to 4 cm after the first 24 hours of leaching and was raised to 3 cm when the leaching was finished. Treated and control plants were maintained outdoors. Treated rice and weed species were compared to controls after 20 and 40 days, respectively, and visually evaluated. Plant response ratings are reported in Tables G-l and G-2 using 0.5 increments on a 0 to 10 scale, where 0 is no effect and 10 is complete control.

Table G-l Effect of Mixtures of Compound 1 with Bensulfuron Methyl on Rice at 0, 1 and 2-cm Transplantation Depths in Outdoor Test

Rice

Application Rate Treated 5 days after transplanting (g a.i./ha) 0-cm planting depth 1 -cm planting depth 2-cm planting depth

Compound Bensulfuron

Observed ι Expected Observed ι Expected Observed ι Expected 1 methyl

64 0 125 2.5

51 0.5 0.5

64 51 3.6 1.5 0.5 0 0.5

I I 125 51 2.5 3.4 1.5 2.9

Table G-l shows mixtures of Compound 1 with bensulfuron methyl provide an unexpected safening effect on rice. This safening effect is most noticeable at shallow planting depths, which tend to produce the most injury. Although commercial rice growers generally try to transplant rice at 2 cm depth, some plants may be inadvertently transplanted less deep. Even the smaller safening at 2-cm planting depth is commercially significant, as it allows greater application rates to be used for better weed control without unacceptable rice injury. Table G-2 Effect of Mixtures of Compound 1 with Bensulfuron Methyl Applied to Weeds at Various Growth Stages in Outdoor Test

Table G-2 Continued

* The effect of 32 g a.i./ha of Compound 1 on the 2.5-leaf stage of Echinochloa oryzicola could not be accurately determined because of stunting due to competition from weeds such as E. kuroguwai, S. pygmaea, C. serotinus, S. juncoides and L. procumbens. For this reason, the listed Expected Effects may be overstated, and the actual effects to be expected from the herbicide mixtures are closer to those observed.

Table G-2 shows mixtures of Compound 1 with bensulfuron methyl having a roughly additive effect against many weeds, including the very important weed Echinochloa oryzicola. To obtain excellent control of this weed, at least 64 g/ha of Compound 1 was needed alone or in combination with bensulfuron methyl. While Compound 1 is very effective at controlling E. oryzicola, it is less effective at controlling Lindernia procumbens, Scirpus juncoides, Cyperus serotinus, Sagittaria pygmaea and Eleocharis kuroguwai at this low application rate. Bensulfuron methyl at 51 g/ha controlled these weeds. The combination of 64 g/ha of Compound 1 with 51 g/ha of bensulfuron methyl provided control of the full-spectrum of weeds. This combination provided at least as strong an effect on each tested weed species as did the herbicides individually.

Besides weed control, rice injury is commercially relevant. As shown in Table G-l, this combination would be expected to significantly injure rice, but instead exhibits an unexpected safening effect. This surprising safening makes the combination commercially very valuable for selective broad-spectrum weed control in rice cultivation.

TEST H

Containers containing a silt loam soil were seeded with the weeds Leptochloa facsicularis and Echinochloa crus-galli and allowed to grow to the 2-3 and 1-3 leaf stages, respectively, before treatment. Rice (Oryza sativa) indica cv. IR-64) and japonica cv. M202 were transplanted and allow to grow to the 5-leaf stage (early tillering) before treatment. All pots were flooded to 3 cm water depth just before treatment and maintained at this depth throughout the experiment. Test compounds were formulated in a non-phytotoxic solvent mixture and added directly to the paddy water. Plants and untreated controls were maintained under greenhouse conditions for 14 days at which time treated plants were compared to untreated controls and visually evaluated. Plant response ratings, summarized in Table H, are based upon a 0 to 100 scale where 0 indicates no effect and 100 is complete control.

Expected results listed for comparison in Table H are calculated according to the Colby Equation. Colby's equation (Colby, S. R. "Calculating Synergistic and Antagonistic Responses of Herbicide Combinations," Weeds, 15(1), pp 20-22 (1967)) calculates the expected additive effect of herbicidal mixtures, and for two active ingredients is of the form:

P_a+b = Pa + Pb - (PaPb 1 0) wherein P_a+t, is the percentage effect of the mixture expected from additive contribution of the individual components,

P_a is the observed percentage effect of the first active ingredient at the same use rate as in the mixture, and Pj, is the observed percentage effect of the second active ingredient at the same use rate as in the mixture.

Table H Effect of Mixtures of Compound 1 with Bensulfuron Methyl Applied to Rice and Two Grass Weeds

* Observed results. f Expected from the Colby Equation.

Table H shows mixtures of Compound 1 with bensulfuron methyl demonstrate a significant safening effect on rice. As this test was conducted in the greenhouse where rice plants are tender, little injury would be expected under field conditions. These mixtures also show a synergistic effect on Leptochloa fasicularis and Echinochloa crus-galli, which is particularly noticeable at moderate application rates which would be expected to give only modest effects. For example, this synergism gave 90% control of Leptochloa fasicularis instead of 30%> expected from application of 16 g/ha of bensulfuron methyl and 175 g/ha of Compound 1. This synergism on weeds is especially valuable in combination with the safening on rice, and is particularly surprising, because rice, Leptochloa fasicularis and Echinochloa crus-galli are all grasses.

TEST I

Containers containing a silt loam soil were seeded with Alisma plantago-aquatica and allowed to grow to the 4-leaf stage before treatment. All pots were flooded to 3 cm water depth just before treatment and maintained at this depth throughout the experiment. Test compounds were formulated in a non-phytotoxic solvent mixture and added directly to the paddy water. Plants and untreated controls were maintained under greenhouse conditions for 14 days at which time treated plants were compared to untreated controls and visually evaluated. Plant response ratings, summarized in Table I, are based upon a 0 to 100 scale where 0 indicates no effect and 100 is complete control. Expected results listed for comparison in Table I are calculated according to the Colby Equation.

Table I Effect of Mixtures of Compound 1 with Bensulfuron Methyl Applied to Alisma plantago-aquatica

* Expected from the Colby Equation.

Table I shows mixtures of Compound 1 and bensulfuron methyl demonstrating substantial synergism on a broad-leafed weed, Alisma plantago-aquatica. Lower application rates are used than in Table H, because this weed is more sensitive than are grass weeds to bensulfuron methyl. As herbicidal effects cannot exceed 100%), the synergism is most dramatic at lower application rates that would be expected to give only modest levels of control. Table I shows that even relatively small amounts of Compound 1, which alone have no effect on Alisma plantago-aquatica, can increase the effect of 1 g/ha of bensulfuron methyl to 80% from 50% expected. This is both remarkable and useful.

TEST J

Containers containing a silt loam soil were seeded with the weed Echinochloa crus- galli and allowed to grow to the emerging leaf stage before treatment. Rice (Oryza sativa) indica cv. IR-64) and japonica cv. M202 were transplanted and allow to grow to the 4-leaf to early tillering stage. All pots were flooded to 3 cm water depth just before treatment and maintained at this depth throughout the experiment. Test compounds were formulated in a non-phytotoxic solvent mixture and added directly to the paddy water. Plants and untreated controls were maintained under greenhouse conditions for 15 days at which time treated plants were compared to untreated controls and visually evaluated. Plant response ratings, summarized in Table J, are based upon a 0 to 100 scale where 0 indicates no effect and 100 is complete control. Expected results listed for comparison in Table J are calculated according to the Colby Equation.

Table J Effect of Mixtures of Compound 1 with Azimsulfuron Applied to Rice and the Grass Weed Echinochloa crus-galli

* Observed results. t Expected from the Colby Equation. Table J shows the effect of mixtures of Compound 1 with azimsulfuron on rice and the very important grass weed, Echinochloa crus-galli. At these application rates, Compound 1 and azimsulfuron, alone and in combination, caused no rice injury. At the same application rates, this test showed significant synergism on Echinochloa crus-galli. For example, application of 32 g/ha of Compound 1 and 8 g/ha of azimsulfuron gave 90% control, instead of 60%) expected. Application of 64 g/ha of Compound 1 and 8 g/ha of azimsulfuron gave 100% control instead of 96% expected.

TEST K

Containers containing a silt loam soil were seeded with the weeds Leptochloa facsicularis and Echinochloa crus-galli and allowed to grow to the 0-2 and emerging leaf stages, respectively, before treatment. Rice (Oryza sativa) indica cv. IR-64) and japonica cv. M202 were transplanted and allow to grow to the 4-5 and 3-5 leaf stages, respectively, before treatment. All pots were flooded to 3 cm water depth just before treatment and maintained at this depth throughout the experiment. Test compounds were formulated in a non-phytotoxic solvent mixture and added directly to the paddy water. Plants and untreated controls were maintained under greenhouse conditions for 15 days at which time treated plants were compared to untreated controls and visually evaluated. Plant response ratings, summarized in Table K, are based upon a 0 to 100 scale where 0 indicates no effect and 100 is complete control. Expected results listed for comparison in Table K are calculated according to the Colby Equation.

Table K Effect of Mixtures of Compound 1 with Azimsulfuron Applied to Rice and two Grass Weeds

* Observed results. f Expected from the Colby Equation.

Table K provides additional test data for mixtures of Compound 1 with azimsulfuron at greater application rates. On the indica rice variety, safening was evident at some application rates. This test was conducted in the greenhouse; under field conditions, less rice injury would be expected. Particularly noteworthy is the strong synergism on the grass weeds Leptochloa facsicularis and Echinochloa crus-galli. For example, application of 8 g/ha of Compound 1 with 32 g/ha of azimsulfuron gave 100% control of Leptochloa facsicularis compared to 0%> expected. Application of 32 g/ha of Compound 1 with 32 g/ha of azimsulfuron gave 100% control of Echinochloa crus-galli compared to 90% expected. This synergism allows lower use rates for control of these important grass weeds, resulting in economic savings and decreased likelihood of rice injury. TEST L

Containers containing a silt loam soil were seeded with Heteranthera limosa and allowed to grow to the 2-leaf stage before treatment. All pots were flooded to 3 cm water depth just before treatment and maintained at this depth throughout the experiment. Test compounds were formulated in a non-phytotoxic solvent mixture and added directly to the paddy water. Plants and untreated controls were maintained under greenhouse conditions for 21 days at which time treated plants were compared to untreated controls and visually evaluated. Plant response ratings, summarized in Table L, are based upon a 0 to 100 scale where 0 indicates no effect and 100 is complete control. Expected results listed for comparison in Table L are calculated according to the Colby Equation.

Table L Effect of Mixtures of Compound 1 with Metsulfuron Methyl Applied to Heteranthera limosa

* Expected from the Colby Equation.

Table L shows mixtures of Compound 1 with metsulfuron methyl at low use rates demonstrating surprising synergism on the weed Heteranthera limosa. For example, 32 g/ha of Compound 1 and 0.5 g/ha of metsulfuron methyl provided 95%> control compared to 0% expected. TEST M

Containers containing a silt loam soil were seeded with Scirpus mucronatus and allowed to grow to the 4-leaf stage before treatment. All pots were flooded to 3 cm water depth just before treatment and maintained at this depth throughout the experiment. Test compounds were formulated in a non-phytotoxic solvent mixture and added directly to the paddy water. Plants and untreated controls were maintained under greenhouse conditions for 21 days at which time treated plants were compared to untreated controls and visually evaluated. Plant response ratings, summarized in Table M, are based upon a 0 to 100 scale where 0 indicates no effect and 100 is complete control. Expected results listed for comparison in Table M are calculated according to the Colby Equation.

Table M Effect of Mixtures of Compound 1 with Metsulfuron Methyl Applied to Scirpus mucronatus

* Expected from the Colby Equation.

Table M shows mixtures of Compound 1 with metsulfuron methyl providing substantial synergism on Scirpus mucronatus. For example, 16 g/ha of Compound 1 and 0.75 g/ha of metsulfuron methyl provided 80% control compared to 0%> expected. Application of 64 g/ha of Compound 1 and 1.5 g/ha of metsulfuron methyl provided 95% control compared to 80% expected. TEST N

Containers containing a silt loam soil were seeded with Scirpus mucronatus and allowed to grow to the 3 -leaf stage before treatment. All pots were flooded to 3 cm water depth just before treatment and maintained at this depth throughout the experiment. Test compounds were formulated in a non-phytotoxic solvent mixture and added directly to the paddy water. Plants and untreated controls were maintained under greenhouse conditions for 21 days at which time treated plants were compared to untreated controls and visually evaluated. Plant response ratings, summarized in Table N, are based upon a 0 to 100 scale where 0 indicates no effect and 100 is complete control. Expected results listed for comparison in Table N are calculated according to the Colby Equation.

Table N Effect of Mixtures of Compound 1 with Chlorimuron Ethyl Applied to Scirpus mucronatus

* Expected from the Colby Equation.

Table N shows mixtures of Compound 1 with chlorimuron ethyl providing substantial synergism. on Scirpus mucronatus. For example, 8 g/ha of Compound 1 and 0.5 g/ha of chlorimuron ethyl provided 80% control compared to 0% expected. Application of 32 g/ha of Compound 1 and 0.5 g/ha of chlorimuron ethyl provided 95% control compared to 80% expected.

TEST O

Individual containers of bulrush (Scirpus juncoides, Sj), small flower umbrella sedge (Cyperus difformis, Cd), common falsepimpemel (Lindernia procumbens, Lp), monochoria (Monochoria vaginalis, Mv) and bamyardgrass (Echinochloa oryzicola, Eo) were seeded and allowed to grow until the 1.5- to 2.5-leaf stage of development. A Saitama clay loam soil was used for this propagation. Rice (Oryza sativa, cv. Nipponbare) was transplanted at 0 and 2 cm depth five days before application of the test compound to the water surface. The compounds evaluated in this test were formulated in a non-phytotoxic solvent mixture and applied to the surface of the water which was contained in each pot. An early and late stage of each weed species was treated, the stage of development being related to the concurrent planting of Scirpus juncoides which was then treated at the 1.5 (early) and the 2.5 (late) leaf stage. Treated plants and untreated controls were maintained under greenhouse conditions until which time treated plants were compared to untreated controls and visually evaluated. The rice plants were evaluated for phytotoxicity 15 days after treatment. Herbicidal effect on the early and late stage treated weeds was evaluated at 35 and 27 days after treatment, respectively. Plant response ratings, summarized in Table O, are based upon a 0 to 100 scale where 0 is no effect and 100 is complete control.

As can be seen from the results listed in Table O, 16 g/ha of the most preferred enantiomer, Compound 1A, provides herbicidal efficacy similar to 64 g/ha of the racemate, Compound 1. This four-fold increase in efficacy is extremely surprising, because even if the less active enantiomer, Compound IB, were completely inactive, enantiomer Compound 1A would be anticipated to be at best only twice as active as the racemate, which contains equal parts of Compounds 1 A and IB. The greatly enhanced efficacy makes Compound 1 A an extremely valuable embodiment of this invention.

Claims

CLAIMS What is claimed is:

1. A compound which is the enantiomer of ╬▒-(2-fluoropheny l)-╬▒- [ 1 -(4- fluorophenyl)ethyl]-lH-l,2,4-triazole-l-ethanol having a negative [╬▒]rj optical rotation in trichloromethane solvent and a proton nuclear magnetic spectrum in deuterated trichloromethane solvent consistent with the pattem: ╬┤ 7.71 (s, IH), 7.69 (s, IH), 7.5 (m, 3H), 6.9-7.3 (m, 5H), 4.8 (d, IH), 4.7 (s, IH), 3.8 (d, IH), 3.4 (q, IH), 1.11 (d, 3H).

2. A herbicidal composition comprising a herbicidally effective amount of the compound of Claim 1 and at least one of a surfactant, a solid diluent or a liquid diluent.

3. A method for controlling the growth of undesired vegetation in a rice crop which comprises applying to the locus of the vegetation a herbicidally effective amount of ╬▒-(2- fluorophenyl)-╬▒-[l -(4-fluorophenyl)ethyl]- IH- 1 ,2,4-triazole- 1 -ethanol.

4. The method according to Claim 3 wherein the ╬▒-(2-fluorophenyl)-╬▒-[l-(4- fluorophenyl)ethyl]-lH-l,2,4-triazole-l-ethanol is the enantiomeric pair having a proton nuclear magnetic spectrum in deuterated trichloromethane solvent consistent with the pattem: ╬┤ 7.71 (s, IH), 7.69 (s, IH), 7.5 (m, 3H), 6.9-7.3 (m, 5H), 4.8 (d, IH), 4.7 (s, IH), 3.8 (d, IH), 3.4 (q, IH), 1.11 (d, 3H).

5. The method according to Claim 3 wherein the ╬▒-(2-fluorophenyl)-╬▒-[l-(4- fluorophenyl)ethyl]-l//-l,2,4-triazole-l -ethanol is the enantiomer having a negative [a]_ optical rotation in trichloromethane solvent and a proton nuclear magnetic spectrum in deuterated trichloromethane solvent consistent with the pattem: ╬┤ 7.71 (s, IH), 7.69 (s, IH), 7.5 (m, 3H), 6.9-7.3 (m, 5H), 4.8 (d, IH), 4.7 (s, IH), 3.8 (d, IH), 3.4 (q, IH), 1.11 (d, 3H).

6. The method according to any one of Claims 3, 4 or 5 wherein the rice crop is in flood culture.

7. The method according to Claim 6 wherein the ╬▒-(2-fluorophenyl)-╬▒-[l-(4- fluorophenyl)ethyl]-lH-l,2,4-triazole-l-ethanol is applied after transplantation of the rice.

8. A mixture comprising a herbicidally effective amount of -(2-fluorophenyl)-╬▒- [l-(4-fluorophenyl)ethyl]-lH-l,2,4-triazole-l-ethanol and bensulfuron methyl.

9. A mixture comprising a herbicidally effective amount of ╬▒-(2-fiuorophenyl)-╬▒- [l-(4-fluorophenyl)ethyl]-lH-l,2,4-triazole-l-ethanol and azimsulfuron.

10. A mixture comprising a herbicidally effective amount of ╬▒-(2-fluorophenyl)-╬▒- [l-(4-fluorophenyl)ethyl]-lH-l,2,4-triazole-l -ethanol and metsulfuron methyl.

11. A mixture comprising a herbicidally effective amount of ╬▒-(2-fluorophenyl)-╬▒- [l-(4-fluorophenyl)ethyl]-lH-l,2,4-triazole-l-ethanol and chlorimuron ethyl.

12. The herbicidal composition comprising a herbicidally effective amount of a mixture of any one of Claims 8, 9, 10 or 11 and at least one of a surfactant, a solid diluent or a liquid diluent.

13. An agent for controlling the growth of undesired vegetation in a rice crop, characterized by containing as an active ingredient, ╬▒-(2-fluorophenyl)-╬▒-[l-(4-fluoro- phenyl)ethyl]- 1 H- 1 ,2,4-triazole- 1 -ethanol.