the compounds of formula i to be used in the composition according to this invention are known as an effective herbicide for killing a variety of annual gramineous weeds such as echinochloa spp ., digitaria spp ., setaria spp . and poa annua spp . and annual cyperus spp . and to be useful for weeding in such crops as rice , maize , soybean and beet plants . the compound of formula ii is also known as a herbicide for killing various annual broad - leaved weeds such as polygonum spp ., chenopodium album , amaranthus albus and stellaria media by treatments during their growing period with such a high security that it does not substantially damage certain crop plants , notably beet . however , each of the compounds of formulae i and ii is not always effective as a completely selective herbicide if used in a small amount or at a low concentration for killing weeds growing in beet farms . thus , the compounds of formula i have an excellent herbicidal activity against gramineous weeds by pre - emergence application without affecting beet crops , but are insufficient in a small amount or at a low concentration to completely kill broad - leaved weeds and gramineous weeds by post - emergence application . on the other hand , the compound of formula ii exhibits an excellent herbicidal activity against broad - leaved weeds by post - emergence application with a high selectivity that it does not substantially affect beet crops , but is ineffective against broad - leaved weeds and gramineous weeds by pre - emergence application . the latter compound is also insufficient in its herbicidal activity when it rains early after application thereof or against old - aged broad - leaved weeds . the combination of the two compounds of formulae i and ii according to this invention makes it possible to kill pre - emergence broad - leaved weeds , post - emergence gramineous weeds and old - aged broad - leaved weeds , which were impossible by application of each single compound . thus , the composition of this invention exhibits a significant herbicidal activity against a wide variety of unwanted weeds including annual gramineous weeds and broad - leaved weeds over the whole growing periods by pre - and post - emergence applications in a small amount or at a low concentration . further , the composition of this invention is resistant to rain after the application , thus lasting a stable herbicidal activity . the high stability under various conditions , the high activity particularly against old - aged broad - leaved weeds and the immediate effect of the composition according to this invention are presumed to be due to the ease of the compound of formula ii to be absorbed into the body of weeds by the aid of the compound of formula i . in fact , this invention is based on the discovery that the combination of the compounds of formulae i and ii not only supplies the deficiencies of the application of each single compound as above - mentioned , but also provides an unexpectedly high synergistic effect in such a manner that the composition of this invention can kill both the gramineous weeds and broad - leaved weeds growing in beet farms simultaneously and exhibit a high herbicidal activity over the whole growing periods of weeds by pre - and post - emergence applications . it has also been found that the composition of this invention is effectively applicable not only to the weeding of beet farms , but also to that of spinach , barley , wheat and maize farms . in a further aspect , therefore , the invention provides a process of inhibiting the growth of weeds in crops of beet , spinach , barley , wheat and maize which comprises applying to the crop area , before or after the crop emerges , a composition comprising a compound of formula i and a compound of formula ii as active ingredients in an amount sufficient to inhibit the growth of the weeds but insufficient substantially to damage the crop plants . in the pre - emergence application , the composition may be applied to soils in which seeds of the crop plants have been sown , preferably by spraying . in the post - emergence application , the composition is usually applied to stalks and leaves of plants , preferably by spraying . examples of the compounds of formula i used in the composition of this invention are as follows : the synergistic effect of the herbicidal composition of this invention is particularly significant at certain specific ratios of the compound of formula i and the compound of formula ii , but the ratio of the two compounds to be incorporated may vary over a relatively wide range . in general , it is desirable to use 0 . 05 to 10 parts by weight , more preferably 0 . 125 to 4 parts by weight , and most preferably 0 . 25 to 2 parts by weight , of the compound of formula ii ( hereinafter referred to as compound c ) per part by weight of the compound of formula i . the herbicidal composition of this invention may be prepared in any form of preparations containing typically 0 . 5 to 80 % by weight of the active ingredients , such as wettable powders or grains , emulsions , powders , grains , granules , flowable suspensions and the like . in preparing the herbicidal composition of this invention , the active ingredients are mixed with a diluent or carrier . suitable solid diluents or carriers include , for example , talc , bentonite , clay , kaolin , diatomaceous earth , white carbon , vermiculite , slaked lime , siliceous sand , calcium carbonate , dolomite , powdered magnesia , fuller &# 39 ; s earth , ammonium sulfate and urea . suitable liquid diluents or carriers include , for example , alcohols , dioxane , acetone , cyclohexane , methylnaphthalene , dimethylformamide and acetonitrile . surface active agents which may be used as emulsifying , dispersing or suspending agent in the composition of this invention may be of the cationic , anionic or non - ionic type . suitable agents of the cationic type include , for example , quaternary ammonium compounds such as cetyltrimethyl ammonium bromide . suitable agents of the anionic type include , for example , soaps , salts of aliphatic mono - esters of sulphuric acid such as sodium lauryl sulfate , and salts of sulfonated aromatic compounds such as dodecylbenzene - sulfonate , sodium , calcium or ammonium lignosulfonate and butylnaphthalene sulfonate . suitable agents of the nonionic type include , for example , the condensation products of ethylene oxide with fatty alcohols such as oleyl alcohol and cetyl alcohol , or with alkyl phenols such as octylphenol , nonylphenol and octylcresol , the partial esters derived from long chain fatty acids and hexitol anhydrides such as sorbitol monolaurate and the condensation products of the said partial esters with ethylene oxide such as polyoxyethylene sorbitan monolaurate . various other additives which are conventionally used in formulating herbicidal compositions such as carboxymethylcellulose and acasia gum may also be used . the dose of the active ingredients of the composition of this invention depends upon weather condition , soil condition , form of the composition , season of the application , method of the application , kind of crop plants , kind of weeds and growth stage of weeds and it is usually in a range of 0 . 5 to 30 kg , preferably 2 to 12 kg and especially 5 to 8 kg per hectare in the soil treatment or the foliage treatment . the composition is usually applied in a concentration of 500 to 30 , 000 ppm , preferably 2 , 000 to 20 , 000 ppm and especially 5 , 000 to 10 , 000 ppm of the active ingredients . in the case of application of the herbicidal composition spraying from an airplane , the concentration of the active ingredients is usually in a range of 10 , 000 to 75 , 000 ppm . for example , 0 . 5 to 1 . 5 kg of the active ingredients is sprayed at a rate of 20 to 50 liter / ha . upon applications , the herbicidal composition of this invention in the form undiluted or diluted with water is applied to soils or stalks and leaves of plants as above - mentioned . it is also possible to add other herbicidal chemical ( s ) to the herbicidal composition of this invention to substantially enhance the herbicidal activity thereof . the present invention will be further explained more specifically by reference to the following formulation embodiments and examples but the invention is not to be construed as being limited thereto . thus , proportions of respective ingredients incorporated and kinds of carriers used can be varied as desired . unless otherwise indicated , all parts , percents , ratios and the like are by weight . 5 - 80 percent , preferably 10 - 70 % and most preferably 15 - 30 %, of the active ingredients , wherein the ratio of the compounds of formulae i and ii is 1 : 0 . 05 - 10 , is dissolved in 5 - 90 %, preferably 30 - 60 %, of a liquid carrier , to which is added 1 - 40 %, preferably 5 - 20 %, of an emulsifying agent . 5 - 80 percent , preferably 20 - 50 %, of the active ingredients , wherein the ratio of the compounds of formulae i and ii is 1 : 0 . 05 - 10 , 1 - 20 %, preferably 5 - 10 %, of a surface active agent and 5 - 85 %, preferably 40 - 70 % of a solid carrier are crushed and mixed well . 0 . 5 - 10 percent , preferably 1 - 5 %, of the active ingredients , wherein the ratio of the compounds of formulae i and ii is 1 : 0 . 05 - 10 , is crushed and mixed well with 90 - 99 . 5 %, preferably 95 - 99 %, of a solid carrier . 0 . 5 - 40 percent , preferably 2 - 10 %, of the active ingredients , wherein the ratio of the compounds of formulae i and ii is 1 : 0 . 05 - 10 , is crushed and mixed well with 60 - 99 . 5 %, preferably 90 - 98 %, of a solid carrier and the mixture is kneaded with the addition of water , granulated and dried to yield granules . a wettable powder is prepared by homogeneously mixing and grinding 30 parts of compound a , 20 parts of compound c , 2 parts of sodium alkylbenzenesulfonate , 3 parts of polyvinylalcohol , 20 parts of white carbon and 25 parts of fine powdered clay . a wettable powder is prepared by homogeneously mixing and grinding 40 parts of compound b , 20 parts of compound c , 2 parts of sodium alkylbenzenesulfonate , 3 parts of polyvinylalcohol , 20 parts of white carbon and 15 parts of diatomaceous earth . a wettable powder is prepared by homogeneously mixing and grinding 30 parts of compound a , 10 parts of compound c , 2 parts of sodium alkylbenzenesulfonate , 3 parts of polyvinylalcohol , 20 parts of white carbon and 35 parts of fine powdered clay . a wettable powder is prepared by homogeneously mixing and grinding 40 parts of compound b , 10 parts of compound c , 2 parts of sodium alkylbenzenesulfonate , 3 parts of polyvinylalcohol , 20 parts of white carbon and 25 parts of fine powdered clay . a wettable powder is prepared by homogeneously mixing and grinding 30 parts of compound a , 30 parts of compound c , 2 parts of sodium alkylbenzenesulfonate , 3 parts of polyvinylalcohol , 20 parts of white carbon and 15 parts of diatomaceous earth . a wettable powder is prepared by homogeneously mixing and grinding 50 parts of compound a , 2 . 5 parts of compound c , 3 parts of polyoxyethylenealkylarylether , 3 parts of calcium lignosulfonate , 30 parts of white carbon and 11 . 5 parts of fine powdered clay . a wettable powder is prepared by homogeneously mixing and grinding 5 parts of compound b , 50 parts of compound c , 2 parts of sodium alkylbenzenesulfonate , 3 parts of calcium lignosulfonate , 10 parts of diatomaceous earth and 30 parts of fine powdered clay . an emulsion is prepared by homogeneously mixing 10 parts of compound a , 20 parts of compound c , 6 parts of polyoxyethylenealkylarylether , 4 parts of sodium alkylarylsulfonate and 60 parts of dimethylformamide . an emulsion is prepared by homogeneously mixing 30 parts of compound b , 5 parts of compound c , 4 parts of sodium alkylarylsulfonate , 6 parts of polyoxyethylenealkylarylether and 55 parts of dimethyl sulfoxide . a composition in the form of granules is prepared by homogeneously mixing and grinding 5 parts of compound a , 5 parts of compound c , 2 parts of polyvinylalcohol , 15 parts of diatomaceous earth and 73 parts of clay , kneading the ground mixture with the addition of water , granulating the mixture and drying the resulting granules . a composition in the form of granules is prepared by dissolving 10 parts of compound a and 0 . 5 parts of compound c in 3 parts of dimethylformamide and spraying 86 . 5 parts of diatomaceous earth in the form of granules with the resulting solution . a composition in the form of granules is prepared by homogeneously mixing and grinding 1 part of compound b , 10 parts of compound c , 1 part of sodium alkylbenzene sulfonate , 5 parts of white carbon , 50 parts of bentonite and 30 parts of talc , kneading the ground mixture , granulating the mixture and drying the resulting granules . a powder composition is prepared by homogeneously mixing and grinding 3 parts of compound b , 1 part of compound c , 0 . 5 parts of white carbon and 95 . 5 parts of clay . a powder composition is prepared by homogeneously mixing and grinding 8 parts of compound a , 0 . 5 parts of compound c , 15 parts of diatomaceous earth , 50 parts of clay and 26 . 5 parts of talc . a powder composition is prepared by homogeneously mixing and grinding 0 . 5 parts of compound b , 5 parts of compound c , 2 parts of white carbon and 94 . 5 parts of clay . the following examples ( tests ) were performed to demonstrate the excellent herbicidal activity of the composition of this invention . in each test , it is suggested that the use of each single compound gives insufficient herbicidal activity , but the combined use of those compounds according to this invention exhibits a higher herbicidal activity than the simple sum of the activities of respective compounds over a wide range of weeds . this example illustrates the herbicidal activities on a variety of unwanted weeds and the phytotoxicity to beet of compositions according to this invention by pre - emergence treatment . thirty ( 30 ) seeds each of beet ( beta vulgaris ), barnyard grass ( echinochloa crusgalli ), annual bluegrass ( poa annua ), smartweed ( polygonum lapathifolium ) and goosefoot ( chenopodium album var . centrorubrum makino ) were sown in farm - soil contained in each of 2 , 000 cm 2 polyethylene containers . after covering the seeds with the soil , each of the wettable powders prepared in examples 1 and 3 in the form diluted with water to give the concentrations of active compounds shown in table 1 was uniformly sprayed on to the soil at an application rate equivalent to 500 liters per hectare . after the lapse of 25 days from the spraying , the fresh weight of the plants tested was measured , from which the growth inhibition (%) was calculated as follows : ## equ1 ## the results obtained are shown in table 1 . by way of comparison , similar tests were conducted wherein each compound used in the composition above was used separately under the same conditions as above and the results are also shown in table 1 . table 1______________________________________herbicidal activity and phytotoxicity to beetby pre - emergence treatmentapplication growth inhibition (%) com - rate barnyard annual smart - goose - pound ( kg / ha ) beet grass bluegrass weed foot______________________________________a 3 0 89 86 23 19b 3 0 81 83 25 20c 2 0 23 63 100 100 1 0 6 20 80 79a 3 + 0 100 100 100 100c 2a 3 + 0 100 100 100 100c 1b 3 + 0 100 100 100 100c 2b 3 + 0 100 100 100 100c 1______________________________________ this example illustrates the herbicidal activities on various unwanted weeds and the phytotoxicity to beet of compositions according to this invention by post - emergence treatment . in each of 2 , 000 cm 2 polyethylene containers filled with a farm - soil , beet ( 1 . 5 to 2 leaved stage ), barnyard grass ( 2 to 2 . 5 leaved stage ), annual bluegrass ( 1 . 5 to 2 leaved stage ), smartweed ( 1 to 2 leaved stage ) and goosefoot ( 1 . 5 to 2 leaved stage ) were grown to such degrees as shown in the above brackets , respectively . each of the wettable powders prepared in examples 2 and 4 was diluted with water to give the concentrations of active compounds shown in table 2 and sprayed onto the stalks and leaves of the growing plants at an application rate of 500 liters per hectare . twenty days after the spraying , the fresh weight of the plants tested was measured , from which the growth inhibition (%) was calculated according to formula iii . the results are as shown in table 2 . table 2______________________________________herbicidal activity and phytotoxicity to beet bytreatment on stalks and leaves in growing stageapplication growth inhibition (%) com - rate barnyard annual smart - goose - pound ( kg / ha ) beet grass bluegrass weed foot______________________________________a 4 0 78 70 13 10b 4 0 75 70 16 14c 2 0 8 14 56 59 1 0 4 9 32 40a 4 + 0 100 100 98 100c 2a 4 + 0 96 100 86 93c 1b 4 + 0 100 100 100 100c 2b 4 + 0 95 100 85 96c 1______________________________________ this example illustrates the herbicidal activities on yellow fox tail ( setaria viridis beauv .) and amaranth ( amaranthus albus ) of compositions according to this invention by pre - emergence and post - emergence treatments . seeds of the test species were placed on the surface of 2 , 000 cm 2 polyethylene containers of soil and covered with 0 . 5 cm thickness of the soil . each of the wettable powders prepared in examples 5 and 4 was diluted with water to give the concentration of active compounds shown in table 3 and sprayed onto the soil in the pre - emergence tests and onto the stalks and leaves of the growing plants in the post - emergence tests at an application rate of 500 liters per hectare . twenty days after the spraying , the fresh weight of the plant tested was measured , from which the growth inhibition (%) was calculated according to formula iii . the results are shown in table 3 . table 3__________________________________________________________________________herbicidal activity by treatment in different growth stagesapplicationrate s . v . a . a . s . v . a . a . s . v . a . a . s . v . a . a . compound ( kg / ha ) pre - emergence 0 . 5 ˜ 1 l 1 ˜ 1 . 5 l 1 . 5 ˜ 2 l 2 . 5 ˜ 3 l 2 . 5 ˜ 3 3 . 5 ˜ 4 . 5__________________________________________________________________________ la 4 98 53 86 50 42 11 10 0b 4 100 58 88 52 47 20 13 7c 4 4 0 0 92 0 79 0 42 1 9 0 0 88 0 51 0 14a 4 + 100 100 100 100 93 97 60 89c 4a 4 + 100 96 100 100 89 92 58 84c 1b 4 + 100 100 100 100 96 99 66 92c 4b 4 + 100 100 98 100 92 96 60 91c 1untreated -- 0 0 0 0 0 0 0 0__________________________________________________________________________ s . v . : setaria viridis beauv . ; a . a . : amaranthus albus 0 . 5 ˜ 1 l : 0 . 5 ˜ 1 leaved stage
a herbicidal composition is provided which is characterized by the combination use as active ingredients of a thiocarbamate derivative of formula i : ## str1 ## wherein one of x and y is a hydrogen and the other is a chlorine and 4 - amino - 3 - methyl - 6 - phenyl - 1 , 2 , 4 - triazin - 5 - one of the formula : ## str2 ## also provided is a process of inhibiting the growth of unwanted plants by applying the herbicidal composition to the plants or to the soil where the plants are grown .