This invention relates to novel herbicidal compositions, particularly aqueous solutions, containing the herbicide N-phosphonomethylyglycine (also known as glyphosate) and an alkyl phenol polyoxyalkylene carboxylic acid-containing surfactant.
N-phosphonomethylglycine, as well as analogous compounds including salts, and the herbicidal properties and formulations containing them, are described in numerous patents, such as U.S. Pat. No. 3,799,758. This patent describes a number of compositions containing N-phosphonomethylglycine and analogous compounds and discloses that the incorporation of a surface-active agent into such compositions "greatly enhances their efficiency". A number of surface-active agents are disclosed in that patent.
The patent also mentions that because N-phosphonomethylglycine itself is relatively insoluble in water, it is generally preferred to utilize the more readily soluble derivatives of N-phosphonomethylglycine, including metal salts and salts of N-phosphonomethylglycine and strong acids, namely those having a pK of 2.5 or less, such as hydrochloric, sulfuric, phosphoric, trifluoracetic, trichloracetic, and the like.
A number of subsequent patents and patent applications describe in more detail particular surfactants which may be used with N-phosphonomethylglycine or its salts. For instance, U.S. Pat. No. 5,180,414 describes compositions of N-phosphonomethylglycine containing certain alkyl polyoxyethylene phosphoric acid ester surfactants. European Patent Application 290,416 describes compositions containing N-phosphonomethylglycine or its salts and an alkoxylated amine having at the most 12 alkoxy groups per molecule. European Patent Application 472,310 describes new surfactant compositions for use with pesticides, including glyphosate, which comprise a polyoxyalkylene alkyl amine containing at least about 7 moles of an oxyalkylene group combined with a second compound which has the property of reducing eye irritantcy. Such eye irritant-reducing compounds include sulfated polyoxyalkylene alkyl phenols, polyoxyalkylene alcohol sulfates, mono- and di-(polyoxyalkylene alcohol)phosphates, mono- and di-(polyoxyalkylene alkyl phenol)phosphates, polyoxyalkylene alkyl phenol carboxylates and polyoxyalkylene carboxylates.
It is an object of the present invention to provide new phosphonomethylglycine-containing compositions, particularly aqueous solutions of N-phosphonomethylglycine which may be readily used for herbicidal application and control of undesirable plants.