AU594513B2 - Selective herbicidal composition having synergistic action for use in cereal cultivation - Google Patents

Description

r _Ij-T, S F Ref: 40794 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

Complete Specification Lodged: Accepted: Published: Priority: Related Art: FOR OFFICE USE: Class Int Class ameirdmeL la c cnti t:1 Secti on 49 and is c L.ct io

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0 o 4 14 Name and Address of Applicant: Ciba-Geigy AG Klybeckstrasse 141 4002 Basle

SWITZERLAND

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d dress for Service: Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: Selective Herbicidal Composition Having for Use in Cereal Cultivation The following statement is a full description of best method of performing it known to me/us Synergistic Action this invention, including the 5845/3 r i ti i 14r -1- 4 5-16639 Selective herbicidal composition having synergistic action for use in cereal cultivation *Winter and spring crops of cereals, especially of "I T wheat and barley, generally contain weeds of very many C different types. These are on the one hand broad-leaved weeds, which belong to the class of dicotyledonous -I T plants, and on the other hand grasses, which belong to the monocotyledonous plants. Of these, the Gramineae family especially is widespread, especially various species of Lolium.

The great variety of weed flora that invades cereal crops has resulted in there also being a variety of herbicidal active ingredients which, in accordance with ftheir specific properties, often produce excellent results but are nevertheless unable to solve all weed Sl 4. problems to a satisfactory extent, either because they are not sufficiently effective against particular problem weeds or because they are not equally suitable for preand post-emergence application, that is to say that those S, active ingredients cannot be used as universally and as I tflexibly as the farmer would like.

The solution that has been most advantageous hitherto consists of an active ingredient mixture of six 1 1 'S 2 parts chlorotoluron and one part terbutryn.

Chlorotoluron is N-(3-chloro-4-methylphenyl)-N'dimethylurea and corresponds to the formula Cl (H2 N-CNH-3- 4* Ga 4 4 0540 4 It tt i I tr trc I C 601CC 0 CC That active ingredient is a powerful grass herbicide, especially against types of wild oats, Alopecurus and Lolium. However, it has an unsatisfactory action against Phalaris and against dicotyledonous weeds, such as Veronica, Papaver, Polygonum, Fumaria, etc. An advantage of chlorotoluron, however, is that it can be used both pre-emergence and post-emergence.

Chlorotoluron is a known substance the manufacture and properties of which are described, for example, in FR-PS 2 001 791.

Terbutryn is 2-methylthio-4-ethylamino-6-tert.and corresponds to the formula CH3S N NHC(CH 3 3 N N NHCH2CH 3 23 t 1 Sii That active ingredient is also an excellent cereal herbicide. Its advantages are that it has a good action p.i S3 against dicotyledonous weeds, such as Veronica, Polygonum, Papaver and Fumaria, as well as a good action against the grass-like weeds of the genera Alopecurus and Phalaris. The disadvantage of terbutryn is that it is relatively ineffective against wild oats and Lolium and that it cannot be used post-emergence or can be used post-emergence only under certain circumstances.

Terbutryn is a known substance the manufacture and properties of which are described, for example, in FR-PS 1 502 307.

A combination of the two active ingredients represented a great improvement over the separate use of those herbicides when cereal fields containing wild oats and Lolium were treated with chlorotoluron (pre- or postemergence) and cereal fields containing predominantly r Phalaris and/or dicotyledonous weeds were treated prefoo emergence with terbutryn.

It was thus possible to solve both weed problems in one operation, and it was found that the action of the rl t two components was increased synergistically in that mixture, without the selectivity for the crops wheat or barley being reduced.

Sulphonylurea herbicides have recently been t introduced for the control of weeds in cereal crops.

They are distinguished by a very powerful herbicidal action and are effective in extremely low quantities of lt i from 5 to 100 g of active ingredient per hectare. They are not only very effective in controlling broad-leaved weeds but also in controlling certain grasses. In tL certain crops, they are to be used only in the postemergence method, and their use is limited since, because of their residual persistence in the soil, dicotyledonous crops subsequently cultivated in the same field could be i at risk.

Surprisingly, it has now been found that it is possible to solve the problem of weed control in cereals -Trit i

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4 4 in outstanding manner using a herbicidal composition that contains as active components chlorotoluron, terbutryn and triasulfuron in a ratio of 100-300:20-60:1, especially of 200:40:1 or preferably of 207:42:1, this mixture being applied both pre- and postemergence, destroying both dicotyledonous weeds and monocotyledonous weeds, including Lolium, Avena and Phalaris, without damaging the cereals, and exhibiting a synergistically increased action against individual problem weeds in that it damages the problem weeds to a greater extent than was to be expected from the sum of the actions of the amounts of the individual components.

Lower total amounts of active ingredient are therefore sufficient to achieve the desired aim of eliminating the weeds.

The present invention relates to a process for the i manufacture of such a herbicidal composition and to a method for producing weed-free cereal cultivation areas S' by the pre- or post-emergence treatment of those areas I or of the cereal when it has emerged, respectively, with S, that novel composition.

The process for the manufacture of the novel composition is characterised in that from 100 to 300 parts S*by weight of N-(3-chloro-4-methylphenyl)-N'-dimethylurea and from 20 to 60 parts by weight of 2-methylthio-4- A ethylamino-6-tert.-butylamino-l,3,5-triazine and 1 part by weight of N-(2-chloroethoxyphenylsulphonyl)-N'-(4methoxy-6-methyl-l,3,5-triazin-2-yl)-urea are intimately mixed with suitable solid or liquid adjuvants or a.

carriers, including surface-active substances, and ground, and converted into the form of scattering agents, dusts, granulates or, especially, waterdispersible granulates.

/i Triasulfuron is N-(2-chloroethoxyphenylsulphonyl)- N'-(4-methoxy-6-methyl-l,3,5-triazin-2-yl)-urea and corresponds to the formula '1 5 0

N

SO2NH-C-NH- OCH3 OCH2CH 2 C1

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k ~1 4 if I ft t( Ii T I I It

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1141 I Cit1.

4 4 I 4.

That active ingredient is a very powerful cereal herbicide and is effective at rates of application of from 5 to 25 g per hectare against almost all broadleaved weeds, and at rates of application of from 10 to 30 g per hectare also against various grasses, such as, for example, species of Setaria, Lolium and Allium. It is used pre- and post-emergence in wheat crops and postemergence in barley crops.

Triasulfuron is a known substance the manufacture and properties of which are described, for example, in EP-PS 44 808.

A great advantage of the preparation according to the invention is also that it can be used in all cerealgrowing regions of the country, irrespective of the weeds that occur, and that it can be applied both pre- and post-emergence. It therefore results in a significant simplification for the user (farmer), both in the amount of work involved and in the method and time of application (before or after the plants have emerged).

The use of the three-component composition according to the invention for selective weed control in cereal crops, especially crops of wheat and barley, has considerable unforeseen advantages compared with the use of the mixture of chlorotoluron and terbutryn, and compared with the use of the herbicidal sulphonylurea triasulfuron alone.

1 1 il j r n 1 i j: t ll-- 4,I I 6 i 4C (li:4 44 44 4r 4 r44 4 44 4 4c (C 44 tC C c ttt 4: 4 44 4 ClC Barley can also be treated by the pre-emergence method, which was not possible with the combination of chlorotoluron and terbutryn. Great success was achieved in the control of Gramineae grasses, which are morphologically similar to the crops. In particular, the composition according to the invention is more successful in combating the Lolium types than is the chlorotoluron/terbutryn combination.

Improved general control of dicotyledonous weeds is achieved, especially when the mixture according to the invention is used in the pre-emergence method.

Finally, it is possible to use smaller amounts than those employed when the known chlorotoluron/terbutryn combination is used, or to use an amount of the sulphonylurea triasulfuron that is proportionately much smaller than that required if it were employed alone.

This not only has ecological and economic advantages; it also reduces the risk of phytotoxic damage being caused to the crops and of resistance problems in subsequent dicotyledonous crops as a result of the rates of application of the herbicide being too high.

The rates of application of total active ingredient are customarily from 0.5 to 2 kg per hectare of cultivated area. It is possible to achieve highly satisfactory results using only from 0.6 to 1.5 kg/ha in the form of aqueous wettable powder dispersions. The compositions may be marketed, for example, preferably in the form of 80% strength wettable powders or waterdispersible granulates.

Compositions according to the invention are manufactured in a manner known per se by intimately mixing and grinding the active ingredients with suitable carriers.

In order to increase the ability of the mixture to be absorbed by the plants, surface-active substances are incorporated into the composition. The active ingredients may be present in, and be used in the form i 4 4.

:i I i 1 ecL~: 7 of, the following preparations: dusts, scattering agents, scattering granulates, such as coated granulates, impregnated granulates and homogeneous granulates, wettable powders and dispersible granulates.

Water-dispersible granulates have proved to be especially suitable.

In order to manufacture solid preparations (dusts, scattering agents, granulates), the active ingredients are mixed with solid carriers. Suitable carriers are, for example, kaolin, talcum, bole, loess, chalk, limestone, lime grit, attaclay, dolomite, diatomaceous earth, precipitated silicic acid, alkaline earth metal silicates, sodium and potassium aluminium silicates (feldspars and mica), calcium and magnesium sulphates, magnesium oxide, ground synthetic materials, fertilisers, such as ammonium sulphate, ammonium phosphate, ammonium nitrate, urea, ground vegetable products, such as grain meal, bark meal, wood meal, nutshell meal, cellulose r' powders, plant extraction residues, active charcoal, r fC other adsorptive carriers, such as highly dispersed urea/formaldehyde polycondensation products having a large inner surface area, etc., in each case individually or as mixtures with one another.

The particle size of the carriers is advantageously not more than approximately 0.1 mm in the case of dusts and 0.2 mm or above in the case of granulates.

iira,' The concentrations of active ingredient in the solid preparations are from 0.5 to There may also be added to those mixtures adjuvants *tt that stabilise the active ingredient and/or nonionic, anionic and cationic substances which, for example, improve the adhesion of the active ingredients to plants i and parts of plants (tackifiers and adhesives) and/or ensure improved wettability (wetting agents) and dispersibility (dispersing agents). Suitable adhesives are, for example: olein/lime mixture, cellulose r I~~r~ 8 tt r t c r tc C C C C 'C C Cf C C Cs C C C SCc derivatives (methylcellulose, carboxymethylcellulose), hydroxyethylene glycol ethers of mono- and di-alkylphenols having from 5 to 15 ethylene oxide radicals per molecule and 8 or 9 carbon atoms in the alkyl radical, lignosulphonic acid, the alkali metal and alkaline earth metal salts thereof, polyethylene glycol ethers (carbowaxes), fatty alcohol polyglycol ethers having from to 20 ethylene oxide radicals per molecule and from 8 to 18 carbon atoms in the fatty alcohol moiety, condensation products of ethylene oxide, propylene oxide, polyvinylpyrrolidones, polyvinyl alcohols, condensation products of urea/formaldehyde, and latex products.

Water-dispersible active ingredient concentrates, that is to say wettable powders or water-dispersible granulates, are compositions that can be diluted with water to any desired concentration. They consist of active ingredient, carrier, if appropriate adjuvants that stabilise the active ingredient, surface-active substances and anti-foam agents. The concentration of active ingredient in those compositions is from 5 to Wettable powders are obtained by mixing and grinding the active ingredients with dispersing agents and pulverulent carriers in suitable devices until the mixture is homogeneous. Suitable carriers are, for example, those mentioned above for the solid preparations. In some cases it is advantageous to use mixtures of different carriers. As dispersing agents there may be used, for example: condensation products of sulphonated naphthalene and sulphonated naphthalene derivatives with formaldehyde, condensation products of naphthalene or naphthalenesulphonic acids with phenol and formaldehyde, and alkali metal, ammonium and alkaline earth metal salts of lignosulphonic acid, also alkylarylsulphonates, alkali metal and alkaline earth metal salts of dibutyl naphthalenesulphonic acid, fatty alcohol iJ t

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I C I e Io C et sulphates, such as salts of sulphated hexadecanols, heptadecanols and salts of sulphated fatty alcohol glycol ethers, the sodium salt of oleylmethyl tauride, ditertiary ethylene glycols, dialkyldilaurylammonium chloride and fatty acid alkali metal and alkaline earth metal salts.

Suitable anti-foam agents are, for example, silicones.

The active ingredients are mixed with the abovementioned adjuvants, ground, sieved and strained in such a manner that the particle size of the solid fraction does not exceed from 0.02 to 0.04 mm.

In the case of scattering granulates and waterdispersible granulates, the compositions according to the invention can be produced, for example, in accordance with the extruding, mixing or spray-drying process. The various components are mixed together before the actual grinding process, for example, until the mixture is homogeneous. Chlorotoluron is preferably ground beforehand, for example in an air-jet mill, and is added to the other components at the end. The composition is finely ground, for example in an air-jet .ii1, before the actual granulating process. Granulation is effected, for example, in a so-called mixing granulator or a Lodige mixer in a moist to wet state. The crude granulate can be dried in a fluidised bed drier or a vacuum drying cabinet until a residual moisture content of less than from 1.5 to 3% at from 40 to 80 0 C is obtained.

Embodiments of the novel composition are described below. Parts are parts by weight.

Scattering granulate The following substances are used to manufacture a 6% strength granulate:

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10 1 0.025 0.25 0.25 89 075 parts o part o part o part o part o parts o parts o 0.8 mm) chlorotoluron terbutryn triasulfuron epoxidised coconut oil cetyl polyglycol ether polyethylene glycol kaolin (particle size from 0.3 to i The active ingredients are mixed with the epoxidised coconut oil and dissolved in 6 parts of acetone. The polyethylene glycol and the cetyl polyglycol ether are then added. The resulting solution is sprayed onto the kaolin, and the acetone is then evaporated off in vacuo.

Water-dispersible granulates The following constituents are used for the manufacture of water-dispersible granulates:

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79 j C$ C C

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Is CC ish Cf sI~ C C Cis IC C is is cc is

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cit C a) 50 9 12 23.5 b) 53 11 0.25 5 4 parts of chlorotoluron parts of terbutryn part of triasulfuron parts of an anionic surfactant, for example Na dibutyl naphthalenesulphonate parts of sulphite waste liquor parts of kaolin parts of chlorotoluron parts of terbutryn part of triasulfuron parts of Na dibutyl naphthalenesulphonate parts of the Na salt of maleic acid anhydride/isobutylene copolymer parts of Na 2

SO

4 parts of an adsorptive carrier, for example highly disperse urea/formaldehyde polyi ~~cI~ 1 C tr e r ct e c tCI:F I fi' tC r E Ct r" c i: e r Cr I i i. I 11 condensation product having a large inner surface area parts of sulphite waste liquor 6.75 parts of kaolin Wettable powders The following constituents are used for the manufacture of a) an 80% strength and b) a 50% strength wettable powder: a) 66.25 parts of chlorotoluron 13.43 parts of terbutryn 0.132 part of triasulfuron parts of sodium lauryl sulphate parts of naphthalenesulphonic acid/phenol sulphonic acids/formaldehyde condensate 3:2:1 10.5 parts of precipitated colloidal silicic acid b) 41.4 parts of chlorotoluron 8.4 parts of terbutryn 0.2 part of triasulfuron parts of sodium dibutyl naphthalenesulphonate or sodium lignosulphonate 3 parts of naphthalenesulphonic acids/formaldehyde condensate 20 parts of kaolin 22 parts of chalk The two active ingredients are applied to the corresponding carriers (kaolin, chalk, silicic acid) and then mixed and finely ground. Wettable powders which have excellent wettability and excellent suspension properties are thus obtained. Suspensions having any desired concentration of active ingredient can be obtained from such wettable powders by dilution with water.

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i C" 44 t 144 i 444 4~r~ i: 14 41 ~~f from 100 to 300 parts of N-(3-chloro-4-methylphenyl)N,_ dimethylurea (chlorotoluron), from 20 to 60 parts of 2- 1' -12 The following field tests were carried out in order to demonstrate the improved action of the composition according to the invention.

Example 1: Control of Lolium rigidum and of broad-leaved weeds in cereal crops by the pre-emergence method 1.1 Winter wheat of the type "Astral" was sown in a field in October, and the field was then divided into plots. The plots were sprayed on the same day with different active ingredients or active ingredient mixtures. Some plots were left untreated and served as control. After 5 months, in March of the following year, the plots were assessed and the condition of the cereal and of the most important weeds was evaluated for damage.

0% plant flourishing as in the untreated control plots 1-99% intermediate degrees of damage 100% total damage, plants dead The results are summarised in the Table below.

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*r 'S .44 P 4 fl*II -r 4 'S .4 '4 Active ingredient or Ratebf application Wheat Loliu Sinapis Veronica Lamium active ingredient g/hectare "Astral" rigidum arvensis hederifolia amplexicaule cc-bination Chlorotoluron 1500 Terbutgyn (1286 214) Triasulfuron 10 0 70 100 95 89 Chlorotoluron 800 Terbutryn (662.5 134.3 0 90 100 93 Triasulfuron 3.2) Chlorotbluron 1000 Terbutryn (882 168 0 92 100 94 100 Triasulfuron 4) Ghlorotoluron 1200 Terbutryn (993.75 201.45 0 98 100 98 100 Triasulfuron 4.8) Control 0 0 0 0 0 8 -n x- "~i

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I 14 1.2 A field was sown in October with winter barley of the type "Alfa", and was then divided into plots. One week after sowing, the plots were treated with active ingredient or active ingredient mixtures. Some plots were left untreated and served as control. The test was evaluated 5 months later, in March of the following year, and the condition of the barley and of the weed grass Lolium rigidum was assessed. The results are summarised in the Table below.

C V t C C C V C C. C C C V

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Active ingredient damage or active ingredient Rate of application Barley Lolium combination -g/hectare "Alfa" rigidum Chlorotoluron 1500 Terbutryn (1286 214) 91 Triasulfuron 10 12 88 Chlorotoluron 800 Terbutryn (662.5 134.3 0 94 Triasulfuron 3.2) Chlorotoluron 1000 Terbutryn (828 168 0 97 Triasulfuron 4) Chlorotoluron 1200 Terbutryn (993.75 201.45 5 98 Triasulfuron 4.8 Control 0 0 1.3 Winter wheat of the type "Capitole" was sown in October. The field was then divided into plots and the plots were sprayed with the active ingredient or the active ingredient mixtures 6 days after sowing. Some plots were left untreated and served as control. The t;r' C CC y ir

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C r 15 success was assessed 5 months later, in March of the following year, by evaluating the damage to the cereal and to the most widespread weeds Raphanus raphanistrum and Sperqularia rubra. The results are summarised in the Table below.

Active ingredient damage or active ingredient Rate of Wheat Raphanus Spergularia combination application "Capitole" raphanistrum rubra g/hectare Chlorotoluron 1500 3 80 Terbutryn (1286 214) Triasulfuron 10 6 93 100 Chlorotoluron 800 5 93 100 Terbutryn (662.5 134.3 Triasulfuron 3.2) Chlorotoluron 1000 3 98 100 Terbutryn (828 168 Triasulfuron 4) Chlorotoluron 1200 5 100 100 Terbutryn 993.75 201.45 Triasulfuron 4.8 Control 0 0 0 1.4 In a further test, winter wheat of the type "Anza" was sown in October. The field was divided into plots and the plots were treated with the active ingredient or with one of the active ingredient combinations 9 days after sowing. After 5 months, in March of the following year, the success of the treatment was assessed, by evaluating the damage to the wheat and to five of the most widespread grasses and weeds. The results are summarised in the Table below.

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1; i t j 41 4'4 damage Active ingredient or Rate of Wheat Lolium Galium Papaver Polygonum Fumaris active ingredient combin- appliccition "Anza" rigidum aparine roheas aviculare offiation g/hectare I cinalis Chiorotoluron 1500 Terbutryn (1286 214) Triasulfuron 10 5 85 95 98 40 Chiorotoluron 800 Terbutryn (662.5 134.3 3 98 86 100 95 100 Triasulfuron 3.2) Chiorotoluron 1200 Terbutryn (993.75 201.45 3 100 94 100 100 100 Triasulfuron 4.8) Control 0 0 0 0 0 0 kZ t^ -i :-g 1 b i I I 1 il 1 1 17 In these tests, improved weed control was achieved using lower rates of application (from 50 to 80%) of the compositions according to the invention than in the case of the known binary active ingredient combination. In contrast to the treatment with triasulfuron, the wheat exhibited no or very little damage.

Example 2: Control of wild grasses and of weadi in cereal crops by the post-emergence method 2.1 Winter barley of the type "Hatif de Grignon" was sown in a field in October. Once the seed had germinated, in the middle of January of the following year, and the young plants had reached the stage of 3 leaves and 2 nodes, the field was divided into plots and V the plots were treated with the active ingredient or an active ingredient mixture. Some plots were left t LV untreated and served as control. The success of the c C treatment was assessed two months later in the middle of May, by evaluating the damage to the barley and to the main weed Veronica hederifolia.

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t Active ingredient or damage active ingredient Rate of application Barley Veronica combination g/hectare "Hatif de hederifolia Grinon Chlorotoluron 1500 Terbutryn (1286 214) Triasulfuron 10 2 Chlorotoluron 800 Terbutryn (662.5 134.3 0 98 Triasulfuron 3.2) Chlorotoluron.+ 1000 Terbutryn (993.75 201.45 0 98 Triasulfuron 4.8 Control 0 0

A

1' I ,I j 18 2.2 In a similar test, winter wheat of the type "Anza" was sown in January. At the beginning of March, when the crop had germinated and the weeds were between the cotyledon and the 4-leaf stage, the field was divided into plots and each plot was treated with the active ingredient or with one of the active ingredient mixtures.

Some plots were left untreated and served as control.

The success of the treatment was assessed 3 months later in June, by evaluating the damage to the wheat and to the four most important weeds. The results are recorded in the Table below.

Sr I rc C C c c r!C ftft ,.ftftfte ftftft "ft 4 ft ft ft ftn ft ft ft ft .4 ft ft ft ft .4 .4 ft ft ft ft ft F, ftft,'ft*ft* 'S ft ft ft ft ft ft (4 .4 .4.4.4 ft ft ftFF ft ft ft I damrage Active ingredient or active ingredient combination Rate of a g/h Chiorotoluron Terbutryn (6:1) Trinsulfuron Chiorotoluron Terbutryn Tr1iasulfuron hlorotoluron Terbutryn Triasulfuron 1500 (1286 214) 10 800 (662.5 134.3 3.2) 1200 (993 .75 201 .45 4.8) 1 100 2 0 control -j ;k-L :i 1

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20 2.3 Winter barley of the type "Dobla" was sown in October. The crop was divided into plots and the plots were treated in November, one month after sowing, when the crop and the grasses were at the germination stage and the broad-leaved weeds had reached a height of from 2 to 4 cm. Some plots were left untreated and served as control. The test was assessed 5 months later, at the end of April, by evaluating the damage to the barley, to the grass Lolium riqidum and to the most widespread weed Matricaria The results are summarised in the Table below.

C C C Ci

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C C C C~ C C

A,

Active ingredient or Rate of Barley Lolium Matricaria active ingredient application. "Dobla" rigidum sp.

conbination g/hectare Chlorotoluron 1500 10 92 99 Terbutryn (1286 214) Triasulfuron 10 10 40 98 Chlorotoluron 800 5 85 100 Terbutryn (662.5 134.3 Triasulfuron 3.2) Chlorotoluron 1000 3 92 100 Terbutryn (828 168 Triasulfuron 4) Chlorotoluron 1200 10 94 100 Terbutryn (993.75 201.45 Triasulfuron 4.8) Control 0 0 0 I

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4 2.4 Winter barley of the type "Robur" was sown in November. In February of the following year, when the crop was beginning to sprout and the weeds were in the early stage (from 1 to 5 cm high), the field was divided into plots and treated with the active ingredient or with one of the active ingredient mixtures. Some plots were left untreated and served as control. The test was assessed two months later, in April, and the damage to the barley, to the grass Lolium rigidum and to the weeds Papaver rhoeas and Veronica hederifolia was evaluated.

The results are summarised in the Table below.

I

I r i; I i: C '1 damage Active inqrredient or Rate of application Barley Lolium Papaver Veronica active ingredient combin- g/hectare, 'Robur' rigidum roheas bederifolia ation Chiorotoluron 15000989'8 Terbutryn (1286 214) 09 99 Triasulfuron 10 0 65 100 57 Chiorotoluron 800 Terbutryn (662.5 134.3 0 99 100 100 Triasulfuron 3.2) Chlorotoluron 1000 Terbutryn (828 168 4) C 98 100 100 Triasulfuron Chlorot.iluron 1200 Terbutryn (993.75 201.45 0 99 100 100 Triasulfuron 4.8) Control 0 0 0 0 -r 23- Winter barley of the type "Caballar" was sown in October. Treatment was effected at the end of May of the following year, when the seed was beginning to sprout and the weeds were in an advanced early stage. The field was sprayed, in plots, with the active ingredient or with one of the active ingredient mixtures. Some plots were left untreated and served as control. The test was assessed three months later, at the end of May, and the damage to the barley, to the grass Lolium rigidum and to the predominant weeds Senecio gallicus and Veronica hederifolia was evaluated. The results are summarised in the Table below.

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r! i A 4* '4 damage Active ingredient or Rate of application Barley Lolium Senecio Veronica active ingredient combin- g/hectare "Caballar" rigidum gallicus hederifolia ation Control. 0 0 0 0 Chlorotoluron 1500098105 Terbutryi (1286 214)098105 Triasulfuron 10 0 70 95 Ohiorotoluron 800 Terbutryn (662.5 134.3 0 90 100 58 Triasulfuron 3.2) Chlorotoluron Terbutryn (828 168 4) 0 95 100 68 Triasulfuron Chlorotoluron 12004 Terbutryn (993.75 201.45 0 98 100 82 Triasulfuron 4.8)

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25 In these tests too, improved weed control was achieved as compared with triasulfuron or the known composition chlorotoluron/terbutryn 6:1. In order to achieve this result, from 55 to 80% of the amount of the chlorotoluron/terbutryn mixture, or proportionately from 32 to 48% in the case of triasulfuron, were used.

iv :1 1 1

Claims (19)

1. Selective herbicidal composition having synergistic action for use in cereal cultivation, characterised in that it contains as active ingredient a combination of N- (3-chloro-4-methylphenyl)-N'-dimethylurea (chloro- toluron), 2-methylthio-4-ethylamino-6-tert.-butylamino- 1,3,5-triazine (terbutryn) and N-(2-chloroethoxy)- phenylsulphonyl-N'-(4-methoxy-6-methyl-l,3,5-triazin-2- yl)-urea (triasulfuron) in a ratio of 100-300:20-60:1, together with inert liquid or solid adjuvants and carriers, including surface-active substances.

2. Composition according to claim 1, characterised in that it contains the active ingredients chlorotoluron, terbutryn and triasulfuron in a ratio of 200:40:1.

3. Process for the manufacture of a novel, selective herbicidal composition for use in cereal cultivation, characterised in that from 100 to 300 parts by weight of N-(3'-chloro-4'-methylphenyl)-N'-dimethylurea (chloro- toluron), from 20 to 60 parts by weight of 2-methylthio-

4-ethylamino-6-tert.-butylamino-s-triazine (terbutryn) and one part of N-(2-chloroethoxyphenylsulphonyl)-N'-(4- methoxy-6-methyl-l,3,5-triazin-2-yl)-urea (triasulfuron) are intimately mixed and ground with suitable solid and/or liquid adjuvants and carriers, surface-active substances are added for the purpose of improving absorption by the plants, the mixture is ground, and the composition is converted into scattering agents, dusts, granulates and, especially, water-dispersible granulates. 4. Process according to claim 3, characterised in that approximately 5 parts by weight of chlorotoluron, one part by weight of terbutryn and 0.025 part of tria- sulfuron are used, and the procedure is such that, after §i r j A) 4 1 I I p.- ::jL 4 I i I I I ii 4 8I 4 '4 4 4 4 it 444* 4 t~ ii 4 It 44t1 I It I 4' I I S III 44 I a 1' I'~ It 1 I 4' 1 4 I. 27 the addition of the adjuvants and the surface-active substances, a wettable powder that is dispersible in water is obtained.

Process according to claim 3, characterised in that the composition is a water-dispersible granulate.

6. Process according to claim 3 or 5, characterised in that the composition is produced in accordance with the extruding, mixing or spray-drying process.

7. Process according to claim 5 or 6, characterised in that the components are mixed until the mixture is homogeneous.

8. Process according to claim 5, 6 or 7, characterised in that the chlorotoluron is ground beforehand and added to the other components at the end.

9. Process according to any one of claims 5 to 8, characterised in that the composition is finely ground in an air-jet mill.

Process according to any one of claims 5 to 9, characterised in that the crude granulates are dried in a fluidised bed drier or in a vacuum drying cabinet until a residual moisture content of less than from 1.5 to 3% at from 40 to 8000 is obtained.

11. Method for producing substantially weed-free cereal cultivation areas and cereal crops, characterised in that a field sown with cereal is treated, before or after the cereal plants emerge, with a herbicidal composition that contains 5 parts of chlorotoluron per part of terbutryn and 0.025 part of triasulfuron, together with customary adjuvants and carriers and a surface-active substance, S' r C C C 28 and the amount of composition is so selected that the total concentration of active ingredients is from 0.5 to 2 kg per hectare of cultivation area.

12. Method for the selective control of weeds in cereal crops, characterised in that the crop or the cultivation area thereof is treated pre- or post-emergence with an amount of from 0.5 to 2 kg per hectare of a herbicidal composition that contains an active ingredient mixture of from 100 to 300 parts of N-(3-chloro-4-methylphenyl)-N'- dimethylurea (chlorotoluron), from 20 to 60 parts of 2- methylthio-4-ethylamino-6-tert.-butylamino-l,3,5-triazine (terbutryn) and one part of N-(2-chloroethoxyphenyl- sulphonyl)-N'-(4-methoxy-6-methyl-l,3,5-triazin-2-yl)- urea (triasulfuron).

13. Method according to claim 12, characterised in that the ratio of active ingredients in the herbicidal com- position is 200 parts of chlorotoluron to 40 parts of terbutryn to one part of triasulfuron.

14. Method according to claim 12, characterised in that the ratio of active ingredients in the herbicidal com- position is 207 parts of chlorotoluron and 42 parts of terbutryn to one part of triasulfuron.

15. Method according to claim 12, characterised in that the rate of application of the active ingredient mixture is from 0.6 to 1.5 kg per hectare.

16. Method according to claim 12, characterised in that the crop is wheat.

17. Method according to claim 12, characterised in that the crop is barley. Ii A. i I--1 -29-

18. A selective herbicidal composition as defined in claim 1 wherein said inert liquid or solid adjuvants and carriers, including surface-active substances are substantially as herein described with reference to the examples disclosing ingredients of scattering granulate, water-dispersible granulates or wettable powders.

19. The method as defined in claim 11 and substantially as herein described with reference to Example 1 or Example 2. A selective herbicidal composition as defined in claim 1 and substantially as herein described with reference to Example 1 or Example 2 I' @'t 0 Sii I L2 4-i DATED this SIXTEENTH day of OCTOBER 1987 Ciba-Geigy AG Patent Attorneys for the Applicant SPRUSON FERGUSON f r i i SBR:ALB:23F lai i