in general the present invention is directed to high - strength herbicidal formulations containing fluroxypyr esters , in particular fluroxypyr meptyl ester . the herbicidal formulation includes the fluroxypyr ester in an amount sufficient to provide the high - strength formulation with no crystallization at temperatures as low as 0 ° c . the high - strength herbicidal formulation includes at least about 300 gae / l to about 350 gae / l based upon the fluroxypyr acid equivalent of the fluroxypyr ester . this typically corresponds to about 430 g / l to about 505 g / l of the fluroxypyr meptyl ester . other esters of fluroxypyr may be suitable for this invention such as , but not limited to , 2 - butoxy - 1 - methylethyl , 2 - butoxyethyl , butyl , 2 - methylpropyl , 2 - ethylhexyl and 1 - decyl esters . the surfactants can be anionic , cationic or nonionic in character . surfactants conventionally used in the art of formulation and which may also be used in the present formulations are described , inter alia , in “ mccutcheon &# 39 ; s detergents and emulsifiers annual ”, mc publishing corp ., ridgewood , n . j ., 1998 and in “ encyclopedia of surfactants ”, vol . i - iii , chemical publishing co ., new york , 1980 - 81 . typical surfactants include salts of alkyl sulfates , such as diethanolammonium lauryl sulfate ; alkylarylsulfonate salts , such as calcium dodecylbenzenesulfonate ; alkyl and / or arylalkylphenol - alkylene oxide addition products , such as nonylphenol - c 18 ethoxylate ; alcohol - alkylene oxide addition products , such as tridecyl alcohol - c 16 ethoxylate ; soaps , such as sodium stearate ; alkylnaphthalenesulfonate salts , such as sodium dibutylnaphthalenesulfonate ; dialkyl esters of sulfosuccinate salts , such as sodium di ( 2 - ethylhexyl ) sulfosuccinate ; sorbitol esters , such as sorbitol oleate ; quaternary amines , such as lauryl trimethylammonium chloride ; polyethylene glycol esters of fatty acids , such as polyethylene glycol stearate ; block copolymers of ethylene oxide and propylene oxide ; salts of mono and dialkyl phosphate esters ; and mixtures thereof . the surfactant or mixture of surfactants is usually present at a concentration of from about 100 g / l to about 200 g / l . the solvent , which typically makes up the remainder of the high - strength herbicidal formulation , is an n , n - dimethyl ( c 6 - c 12 ) alkylamide . n , n - dimethyl ( c 6 - c 12 ) alkylamides are commercially available under various tradenames including , for example , agnique ke 3658 and 3308 ( cognis inc .) or genagen 4166 and 4296 ( clarian gmbh ), and are often supplied as mixtures such as n , n - dimethyloctanamide / decanamide . the solvent is usually present at a concentration from about 300 g / l to about 560 g / l , more preferably from about 350 g / l to about 450 g / l . the high - strength , herbicidal formulation does not exhibit separation or precipitation ( or crystallization ) of any of the components at low temperatures . for example , the high - strength formulation remains a clear solution at temperatures below about 10 ° c ., more preferably at temperatures about 0 ° c . in addition to the formulations set forth above , the present invention also embraces the compositions of these fluroxypyr ester formulations in combination with one or more additional compatible ingredients . other additional ingredients may include , for example , one or more other herbicides , dyes , and any other additional ingredients providing functional utility , such as , for example , stabilizers , fragrants , viscosity - lowering additives , and freeze - point depressants . additional herbicidal compounds employed as supplements or additives should not be antagonistic to the activity of the fluroxypyr ester composition as employed in the present invention . suitable herbicidal compounds include , but are not limited to 2 , 4 - d , 2 , 4 - mcpa , ametryn , aminopyralid , asulam , atrazine , butafenacil , carfentrazone - ethyl , chlorflurenol , chlormequat , chlorpropham , chlorsulfuron , chlortoluron , cinosulfuron , clethodim , clopyralid , cyclosulfamuron , pyroxsulam , dicamba , dichlobenil , dichlorprop - p , diclosulam , diflufenican , diflufenzopyr , diuron , glyphosate , hexazinone , imazamox , imazapic , imazapyr , imazaquin , imazethapyr , imazosulfuron , mcpa , metsulfuron - methyl , picloram , pyrithiobac - sodium , sethoxydim , sulfometuron , sulfosate , sulfosulfuron , tebuthiuron , terbacil , thiazopyr , thifensulfuron , triasulfuron , tribenuron and triclopyr . the herbicidal formulations of the present invention can be co - formulated with the other herbicide or herbicides , tank mixed with the other herbicide or herbicides , or applied sequentially with the other herbicide or herbicides . dyes may be used in the formulated composition as a marker . generally , a preferred dye can be any oil - soluble dye selected from epa &# 39 ; s approved list of inerts exempt from tolerance . such dyes may include , for example , d & amp ; c red # 17 , d & amp ; c violet # 2 , and d & amp ; c green # 6 . dyes are generally added to the composition by adding the desired amount of dye to the formulated composition with agitation . dyes are generally present in the final formulation composition in a concentration of about 0 . 1 - 1 . 0 % by weight . the compositions of the present invention are diluted with water prior to being applied . the diluted compositions usually applied to cereals and range and pastures generally contain about 0 . 0001 to about 5 . 0 weight percent the fluroxypyr ester . a high - strength formulation was prepared containing 333 gae / l of fluroxypyr meptyl ester by dissolving 480 g / l technical fluroxypyr meptyl ester with stirring into 404 g / l genagen 4166 ( clarian gmbh ; mixture of n , n - dimethyloctanamide / decanamide ), 13 g / l soprophor flk ( rhodia inc ; polyethylene tristyrylphenol phosphate , potassium salt ), 78 . 5 g / l tensiofix n9811 hf ( omnichem nv ; proprietary anionic - nonionic blend ) and 78 . 6 g / l ethoxylated tristyrylphenol at room temperature . unlike the commercial formulation based on aromatic hydrocarbon solvents , which required packaging material with high barrier properties , e . g ., fluorinated hdpe or metal or metal lined containers , to prevent migration through the packaging material , this formulation can be packaged in standard hdpe containers . in addition , seals and o - rings are much less sensitive to the new formulation compared to the commercial formulation based on aromatic hydrocarbon solvents . the formulation of example 1 was cooled and the crystallization point was determined to be less than − 1 ° c . a seeded sample of the formulation did not crystallize at − 5 ° c . after 2 - 3 weeks , but did form a small amount of crystals after 3 - 4 months at − 9 . 9 ° c . the crystals that did form went back into solution upon warming to room temperature with gentle agitation .
this invention relates to a high - strength herbicidal formulation containing high concentrations of fluroxypyr ester in an n , n - dimethyl alkylamide solvent which exhibits significantly greater low temperature stability at high concentrations .