according to the present invention , since the herbicidal composition is in a solid form and contains a thickening agent , it is difficult to swallow in the solid form itself and , if an amount of the composition corresponding to a lethal dose to human beings is dissolved in a glass of water , only a non - fluidizable mixture , which is difficult to swallow , is obtained . of course , the present solid herbicidal composition can be changed to an aqueous solution by diluting the composition with a large amount of water . however , since the paraquat concentration of this diluted solution is very low , a lethal amount cannot be ingested unless a remarkably large amount of the diluted solution is drunk . this is practically difficult and the effects of nauseants can be utilized to decrease the likelihood of death from such ingestion . furthermore , since the present solid herbicidal composition can be stored and transported in glass and plastic vessels , and since the present solid herbicidal composition can be used on - site by diluting with water , there is no substantial difference between the present solid herbicidal composition and conventional commercially available paraquat solutions in the transportation , handling , and applicability thereof . when diluting the present solid herbicidal composition with a large amount of water for use on - site , the present solid herbicidal composition becomes a low viscosity solution suitable for spraying . furthermore , the solid herbicidal composition according to the present invention may optionally contain , in addition to the essential paraquat and thickening agent , various conventional ingredients such as colorants , odorants , and nauseants , to further improve the safety thereof . in addition , surfactants and other herbicidal active components also can be included in the present herbicidal composition to improve the herbicidal effects and the applicability of the herbicidal composition . the paraquat usable in the present herbicidal composition is substantially in the form of a solid . accordingly , 1 , 1 &# 39 ;- dimethyl - 4 , 4 &# 39 ;- bipyridylium salts ( e . g ., dichloride , dibromide , and bismethylsulfate or the complex salts with , for example , manganese , iron , urea , thiourea , p - aminophenol , catechol ) in the form of crystals can be directly mixed with the thickening agent . however , the industrially or commercially available aqueous paraquat solutions also can be used in the preparation of the present solid herbicidal composition by adding a water - absorbing inorganic fine powder to form an apparently water - free fluidizable solid paraquat prior to mixing with the thicking agent . any water - absorbing inorganic fine powder can be used for this purpose so long as the herbicidal effects of the paraquat and the characteristics of the thickening agents are not adversely affected . examples of such water - absorbing inorganic fine powders are white carbon , diatomaceous earth , finely divided calcium silicate , perlite , calcined kaoline , and zeolite . these can be used alone or in any mixture thereof . there are no critical limitations to the addition amount of the water - absorbing inorganic fine powder , as long as the paraquat solution can be substantially solidified . for example , when an about 40 % aqueous paraquat dichloride solution is used , an equal amount or more , based on the amount of the water contained in the paraquat dichloride solution , of the inorganic powder is generally used in the case of , for example , white carbon , finely divided calcium silicate , and perlite , and two times or more , based on the amount of the water contained in the paraquat dichloride solution , of the inorganic powder in generally used in the case of , for example , diatomaceous earth , calcined kaoline , and zeolite . although there is no critical limitation to the upper limit of the amount of the inorganic powder , generally speaking , the maximum amount of the inorganic powder is ten times the amount of water in the paraquat dichloride solution , mainly from an economical viewpoint . there are no critical limitations to the paraquat concentration of the present solid herbicidal compositions . however , when the paraquat concentration is too low , only a small dilution ratio of the composition with water is required to obtained the desired concentration when spraying on - site and , therefore , spraying tends to become difficult from the standpoint of both the viscosity and the spraying amount , and the efficiency of the transportation and storage also tends to be decreased . on the other hand , when the paraquat concentration in the present herbicidal composition is too high , the above - mentioned problems do not arise but the allowable safety range tends to become small from the point of view of preventing the possible occurrence of toxic or poisonous accidents . for these reasons , the practically preferable concentration range of the paraquat in the present herbicidal compositions is from about 3 % by weight to 30 % by weight . the thickening agents usable in the present invention are those which are capable of increasing the viscosity or forming the gel with the addition of a relatively small amount of water to the solid herbicidal composition at an ambient temperature in a short period of time . there are no specific limitations to the types of the thickening agents as long as the above - mentioned requirements are fulfilled . various natural and synthetic thickening agents can be used in the present invention . typical examples of such thickening agents are alginic acid salts , propylene glycol alginates ; carrageenan , guar gum , modified guar gum , xanthan gum , modified xanthan gum , carboxymethyl cellulose salts , methyl cellulose , hydroxyalkyl cellulose , pectine , locust bean gum , carboxymethyl starch salts , pullulan , polyvinyl alcohol , polyvinyl pyrrolidone , polyacrylic acid salts , and polyacryl amide . these thickening agents may be used alone or in any mixture thereof . furthermore , various conventional acids or salts also may be used in the present herbicidal compositions to further improve the gellation or thickening characteristics of the present solid herbicidal composition . the addition of inorganic salts to the present herbicidal composition can further improve the gellation properties of the present herbicidal compositions . there are no definite concentrations of the thickening agents in the present herbicidal compositions since the concentrations largely depend upon the type of thickening agent and the concentration of the paraquat component . as one practical measure , the thickening agent can be used in an amount such that the herbicidal compositions causes gellation , when approximately 3 g ( i . e ., the above - explained lethal dose of paraquat for humans ) or more , in terms of paraquat cation , of the herbicidal composition according to the present invention is diluted with approximately 40 ml of water ( i . e ., the above - explained average amount drunk in one mouthful by an adult human ). that is , when the paraquat concentration of the present solid herbicidal composition is 3 % to 30 % by weight , the thickening agent can be added in an amount such that all of the composition becomes a high viscous liquid or gel that cannot be easily swallowed when the present herbicidal composition is diluted with a four - tenths ( 4 / 10 ) amount of water in the case of a paraquat concentration of 3 %, to 4 times the amount of water in the case of a paraquat concentration of 30 %. furthermore , the concentration of the thickening agent in the present herbicidal composition should be such that the composition becomes an easily sprayable low viscosity liquid when the composition is diluted with water for practical use . thus , generally speaking , the thickening agent can be added to the present herbicidal composition in an amount such that the composition becomes an easily sprayable low viscosity liquid for practical use , when the composition is diluted with 50 times the amount of water in the case of a paraquat concentration of 3 %, to 500 times the amount of water in the case of a paraquat concentration of 30 %. more specifically , the concentration of the thickening agent in the present herbicidal concentration is preferably more than 0 . 5 times but less than 15 times , more preferably 0 . 6 times to 12 times , of the amount of the paraquat ( i . e ., cation ) in the composition , although the concentration depends upon the type of thickening agent used . the solid herbicidal composition according to the present invention may further contain , as an optional component , conventional colorants , odorants , nauseants , and the like to improve the safety of the paraquat herbicide as well as surfactants and other herbicidal active components to improve the herbicidal effects . however , it should be noted that these optional components should be added in such an amount that the herbicidal effects and the other characteristics of the present composition are not adversely affected . the present invention will be further explained by , but is by no means limited to , the following examples and test examples . in the examples , &# 34 ; parts &# 34 ; and &# 34 ;%&# 34 ; are all by weight unless otherwise specified . paraquat wettable powders were prepared by uniformly mixing and grinding solid paraquat components and other ingredients in the following formulation ratios : ______________________________________ ( 1 ) paraquat dichloride 25 partssodium carboxymethyl - starch 75 parts ( primojel ®: matsutani kagaku kogyoco ., ltd . )( 2 ) paraquat dichloride 25 partsguar gum 35 parts ( emco gum ® csa 200 / 50 : meyhallchemical a . g .) white carbon 40 parts ( carplex ® # 80 : shionogi & amp ; co ., ltd ., hereinbelow &# 34 ; white carbon &# 34 ;)( 3 ) paraquat dichloride 15 partspullulan 60 parts ( pullulan ® pf30 : hayashibaraseibutsukagaku kenkyusho k . k . ) white carbon 20 partssurfactant ( polyoxyethylene nonylphenyl 5 partsether )( 4 ) paraquat dichloride 15 partspolyvinyl pyrrolidone 60 parts ( polyvinyl pyrrolidone pvp k - 90 : wako pure chemical industries , ltd .) white carbon 20 partssurfactant 5 parts ( polyoxyethylene higher aliphatic alcoholether )( 5 ) paraquat dichloride 15 partscarboxymethyl starch 60 parts ( solvitose ® c - 5 : matsutani kagakukogyo co ., ltd .) white carbon 20 partssurfactant 5 parts ( polyoxyethylene alkylamine )( 6 ) paraquat dichloride 25 partsxanthan gum 20 parts ( kelzan ®: kelco division of merck , hereinbelow &# 34 ; xanthan gum &# 34 ;) white carbon 30 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether ) foaming agentmalic acid 10 partssodium bicarbonate 10 parts ( 7 ) paraquat dimethylsulfate 30 partsxanthan gum 40 partswhite carbon 25 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether ) ______________________________________ paraquat wettable powders were prepared by first adding the water - absorbable inorganic fine powder listed below to a concentrated paraquat solution ( i . e ., aqueous solution containing 37 % by weight of paraquat dichloride ) to form a solid mixture , followed by the addition of the other ingredients in the following formulation ratios . the resultant mixtures were uniformly mixed and ground . ______________________________________ ( 8 ) concentrated paraquat solution 27 partssodium alginate 45 parts ( kelgin ® hv : kelco division of merck ) white carbon 23 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether )( 9 ) concentrated paraquat solution 40 partspropylene glycol alginate 20 parts ( kimiroid ® hv : kimitsu kagaku kogyok . k ) white carbon 35 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether )( 10 ) concentrated paraquat solution 27 partscarrageenan 45 parts ( takaragen ® g50 : takagen corporation ) white carbon 23 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether )( 11 ) concentrated paraquat solution 40 partsguar gum 15 parts ( emco gum ® csa 200 / 50 ) white carbon 35 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether ) nauseant 1 part ( emetine hydrochloride ) odorant 4 parts ( β - phenethyl alcohol )( 12 ) concentrated paraquat solution 40 partsmodified guar gum 15 parts ( jaguar ® hp - 8 : meyhall chemical ag ) white carbon 35 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether ) nauseant 1 part ( tartar emetic ) β - phenethyl alcohol 4 parts ( 13 ) concentrated paraquat solution 40 partsxanthan gum 15 parts ( kelzan ®) white carbon 30 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether ) anhydrous sodium sulfate 10 parts ( 14 ) concentrated paraquat solution 27 partssodium carboxymethyl cellulose 45 parts ( sunrose ® sn 20tc : sanyokokusaku pulp co ., ltd .) white carbon 23 partssurfactant 4 parts ( polyoxyethylene nonylphenyl ether )( 15 ) concentrated paraquat solution 50 partsmethyl cellulose 10 parts ( maporose ® m - 10000 : matsumoto yushiseiyaku k . k . ) white carbon 36 partssurfactant 4 parts ( polyoxyethylene nonylphenyl ether )( 16 ) concentrated paraquat solution 20 partssodium carboxymethyl starch 57 parts ( primojel ®) white carbon 18 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether )( 17 ) concentrated paraquat solution 27 partspolyvinyl alcohol 45 parts ( pva 117s : kuraray co ., ltd .) white carbon 23 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether )( 18 ) concentrated paraquat solution 40 partspolyacrylamide 24 parts ( viscomate ® ns : showa denko k . k . ) white carbon 31 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether )( 19 ) concentrated paraquat solution 27 partspectin 45 parts ( genu pectin bb rapid set ; thecopenhagen pectin factory ltd .) white carbon 23 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether )( 20 ) concentrated paraquat solution 40 partsxanthan gum 14 parts ( kelzan ®) locust bean gum 10 parts ( meyprodyn ® 200 : meyhall chemical ag ) white carbon 31 partssurfactant 5 parts ( polyoxyethylene nonylphenyl ether )( 21 ) concentrated paraquat solution 40 partsxanthan gum 18 parts ( kelzan ®) diatomaceous earth 37 parts ( radiolite : showa kagaku k . k . ) surfactant 5 parts ( polyoxyethylene nonylphenyl ether ) ______________________________________ of the following ingredients , the concentrated paraquat solution used in examples 8 to 21was mixed with white carbon to form a solid mixture , followed by mixing the other ingredients . the resultant mixture was uniformly mixed and ground , and then granulated by spraying water containing 2 % of pvp k - 90 in a fluid bed type granulator . ______________________________________concentrated paraquat solution 54 partsguar gum 9 parts ( emco gum ® csa 200 / 50 ) white carbon 34 parts ( carplex ® # 80 ) surfactant 3 parts ( polyoxyethylene nonylphenyl ether ) ______________________________________ the resultant paraquat wettable granules , after drying in the fluid bed , had the following composition . ______________________________________paraquat dichloride 30 partsguar gum 14 partswhite carbon 51 . 5 partssurfactant 4 . 5 parts______________________________________ paraquat wettable powders having the following compositions were prepared by mixing the concentrated aqueous paraquat dichloride solution with white carbon to form a solid mixture . the resultant solid mixture was uniformly mixed with the other ingredients , followed by drying to evaporate the water from the mixture . ______________________________________ ( 23 ) paraquat dichloride 35 partsguar gum 23 parts ( emco gum ® csa 200 / 50 ) white carbon 42 parts ( 24 ) paraquat dichloride 35 partscarrageenan 23 parts ( takaragen : takagen corpcration ) white carbon 42 parts ( 25 ) paraquat dichloride 35 partsxanthan gum 23 parts ( kelzan ®) white carbon 42 parts______________________________________ a 30 g amount of the solid composition prepared in example 1 was mixed with 150 ml of water while stirring so as to obtain a mixture having a paraquat dichloride concentration of 5 %. the mixture became pasty shortly after the water was added . thus , a pasty mixture , which is impossible to swallow , was obtained . on the other hand , the paraquat dichloride composition prepared in example 1 was diluted with water in such a ratio that 50 g of the effective component was included in 150 liters of the diluted composition . the diluted herbicidal composition thus obtained was sprayed under pressure onto foliage ( or stems and leaves ) of crabgrass , purple nutsedge , common lambsquarter , pigweed , and barnyard millet , grown in test pots , by using a pressure type atomizer in such an amount that 50 g of the active component per 10 are was applied . prior to the spraying , a conventional nonionic type spreading agent was added to the herbicidal composition . during the spraying , clogging of the spray nozzle of the atomizer did not occur . when the herbicidal effects were compared with those of commercially available paraquat dichloride solution 5 days after the treatment , no substantial difference was observed . a 50 g amount of the solid composition prepared in example 11 was mixed with 150 ml of water while stirring so as to obtain a mixture having a paraquat dichloride concentration of 5 %. the mixture became pasty shortly after the water was added . thus , a pasty mixture , which is impossible to swallow , was obtained . on the other hand , the paraquat dichloride composition prepared in example 11 was diluted with water in such a ratio that 50 g of the effective component was included in 150 liters of the diluted composition . the diluted herbicidal composition thus obtained was sprayed under pressure onto the foliage of crabgrass , purple nutsedge , common lambsquarter , pigweed , and barnyard millet grown in test pots , by using a pressure type atomizer in such an amount that 50 g of the active component per 10 are was applied . prior to the spraying , a conventional nonionic type spreading agent was added to the herbicidal composition . during the spraying , clogging of the spray nozzle of the atomizer did not occur . when the herbicidal effects were compared with those of a commercially available paraquat dichloride solution 5 days after the treatment , no substantial difference was observed . a 50 g amount of the solid composition prepared example 13 was mixed with 150 ml of water while stirring so as to obtain a mixture having a paraquat dichloride concentration of 5 %. the mixture became pasty shortly after the water was added . thus , a pasty mixture , which is impossible to swallow , was obtained . on the other hand , the paraquat dichloride composition prepared in example 13 was diluted with water in such a ratio that 50 g of the effective component was included in 150 liters of the diluted composition . the diluted herbicidal composition thus obtained was sprayed under pressure onto the foliage of crabgrass , purple nutsedge , common lambsquarter , pigweed , and barnyard millet grown in test pots , by using a pressure type atomizer in such an amount that 50 g of the active component per 10 are was applied . prior to the spraying , a conventional nonionic type spreading agent was added to the herbicidal composition . during the spraying , clogging of the spray nozzle of the atomizer did not occur . when the herbicidal effects were compared with those of a commercially available paraquat dichloride solution 5 days after the treatment , no substantial difference was observed . a 40 g amount of the solid composition prepared in example 15 was mixed with 150 ml of water while stirring so as to obtain a mixture having a paraquat dichloride concentration of 5 %. the mixture became pasty shortly after the water was added . thus , a pasty mixture , which is impossible to swallow , was obtained . on the other hand , the paraquat composition prepared in example 15 was diluted with water in such a ratio that 50 g of the effective component was included in 150 liters of the diluted composition . the diluted herbicidal composition thus obtained was sprayed under pressure onto the foliage of crabgrass , purple nutsedge , common lambsquarter , pigweed , and barnyard millet grown in test pots , by using a pressure type atomizer in such an amount that 50 g of the active component per 10 are was applied . prior to the spraying , a conventional nonionic type spreading agent was added to the herbicidal composition . during the spraying , clogging of the spray nozzle of the atomizer did not occur . when herbicidal effects were compared with those of a commercially available paraquat dichloride solution 5 days after the treatment , no substantial difference was observed . the herbicidal effects of the paraquat dichloride wettable powders obtained in examples 23 to 25 were evaluated in an agricultural field . as reference examples , a 24 % aqueous paraquat dichloride solution and a 32 % bialaphos liquid agent were used . the weeds used for the test were crabgrass having a height of 25 to 30 cm , smartweed having a height of 50 cm , common lambsquarter having a height of 50 cm , and pigweed having a height of 25 cm . the area in each test was 1 . 5 m × 2 m ( i . e ., 3 m 2 ). the diluted herbicidal composition samples containing 0 . 3 % of a surfactant were sprayed by using a pressure type spray atomizer at an active component amount of 0 . 5 or 1 kg a . i . ( i . e ., active ingredient )/ ha and at a spraying water amount of 1000 l / ha . six days after the spraying , the herbicidal effects were observed according to the following standard the results are as shown in table 1 . as is clear from the results shown in table 1 , since the grass height at the time of the treatment is relatively large , complete killing was not obtained at a rate of 0 . 5 kg a . i ./ ha . however , in the case of 1 . 0 kg a . i ./ ha , good results were obtained and there was no substantial difference between the compositions of examples 23 and 25 and the conventional paraquat dichloride solution . table 1__________________________________________________________________________sample rate weed controlcomposition no . ( kg a . i ./ ha ) crabgrass smartweed lambsquarter pigweed__________________________________________________________________________example no . 23 0 . 5 60 93 70 80 1 . 0 95 95 100 100example no . 24 0 . 5 85 85 90 93 1 . 0 98 100 100 100example no . 25 0 . 5 90 90 90 98 1 . 0 90 100 100 100paraquat dichloride 0 . 5 80 75 85 95 1 . 0 93 98 100 100bialaphos 0 . 5 60 93 70 80 1 . 0 95 90 100 100control -- 0 0 0 0 ( no treatment ) __________________________________________________________________________
a contradeglutitious solid herbicidal composition comprising a 1 , 1 &# 39 ;- dimethyl - 4 , 4 &# 39 ;- bipyridylium salt in a substantially solid state and a thickening agent and , optionally , a water absorbable inorganic fine powder . this composition is difficult to swallow in its original form or even when diluted in a glass of water . the composition does not impair the inherent herbicidal effects and applicability of paraquat .