Herbicidal mixture, comprising an imidazolinone herbicide and an adjuvant

The present invention relates to a herbicidal mixture of an imidazolinone herbicide and an adjuvant.

The imidazolinone herbicides of the present invention encompass: imazamox, imazapic, imazapyr, all of those are further specified in e.g. C. D. S. Tomlin, “The Pesticide Manual”, 13^th Edition, BCPC (2003), Index 5, 1337-1344 and http://www.hclrss.demon.co.uk/index_cn_frame.html.

Referring to imidazolinone herbicides or specific imidazolinone herbicide species in this application shall mean the compounds as mentioned above, as well as their a) salts, e.g. salts of alkaline or earth alkaline metals or ammonium or organoammonium salts, for instance, sodium, potassium, ammonium, preferably isopropyl ammonium etc.; b) respective isomers, e.g. stereo isomers such as the respective enantiomers, in particular the respective R- or S-enantiomers (including salts, ester, amides), c) respective esters, e.g. carboxylic acid C1-C8-(branched or non-branched) alkyl esters, such as methyl esters, ethyl esters, isopropyl esters, d) respective amides, e.g. carboxylic acid amides or carboxylic acid C1-C8-(branched or non-branched) mono or di alkyl amides, such as dimethylamides, diethylamides, diisopropyl amides or e) any other derivative which contains the above imidazolinone structures as structural moiety.

In particular the term imidazolinone herbicide or reference to specific imidazolinone herbicides herein, such as, imazamox, imazapic, imazapyr, shall include alkylammonium salts, preferably isopropylammonium salts, for example diisopropylammonium- or monoisopropylammonium salts.

Further suitable imidazolinone herbicides are the R-isomers, e.g. R-imazamox, R-imazapic, R-imazapyr, in particular R-imazapyr. These compounds are known e.g. from U.S. Pat. No. 5,973,154 B (American Cyanamid Company) and U.S. Pat. No. 6,339,158 B1 (American Cyanamid Company).

EP 0 356 812 A2 discloses tank-mix compositions of certain herbicides, including imazaquin and imazethapyr, with low foaming nonionic alkylpolyoxyalkylene polyethers and for example anionic surfactants such as partial phosphate esters of monohydroxy-functional polyoxyalkylene ethers.

EP 0 356 812 A is silent as to weed control in the presence of trees.

It is an object of the present invention to provide a herbicidal mixture which comprises herbicidal mixtures of an imidazolinone herbicide and an adjuvant and whose herbicidal activity is higher than the activity of the pure active compound.

This object was achieved by a herbicidal mixture, comprising

• a) a herbicidally effective amount of an imidazolinone herbicide selected from the group consisting of imazamox, imazapic, imazapyr,
• b) an adjuvant comprising at least one of the following components: a partial phosphoric ester or a partial sulfuric ester of a monohydroxy-functional polyalkyl ether
  • and optionally
• c) further additives.

The herbicidal mixture according to the invention displays a synergistic effect and is selective for those crop plants which are also compatible with the individual compounds.

Suitable adjuvants b) comprise partial phosphoric ester or partial sulfuric ester of a monohydroxy-functional polyalkyl ether.

These partial esters are prepared by methods well known to those skilled in the art, for example by reacting one of the well known and commercially monohydric polyoxyalkylene ethers with sulfuric acid or phosphoric acid or their chemical equivalents. The sulfate ester so obtained consist predominantly of the half ester (mono ester) while the phosphate esters generally contain both, mono- and diesters. Also useful are the simple salts of these surfactants, for example, the alkali metal, alkaline earth metal or ammonium salts. The sulfate esters may be prepared for example by reacting a suitable mono-functional polyoxyalkylene ether with sulfuric acid or its chemical equivalent, preferably sulfamic acid or sulfurtrioxide. Phosphate esters are described, for example, in U.S. Pat. No. 5,877,112 column 2, lines 32 to 67 (included herein by reference) and may be prepared, for example, by reaction of the monofunctional polyoxyalkylene ether with phosphoric acid, diphosphorus pentoxide, polyphosphoric acid or phosphorus oxytrichloride. Methods of preparation are described in the treatise “Nonionic Surfactants”, Martin Schick, Ed., Marcel Dekker, New York, 1967, chapter 11, pages 372-394.

Suitable partial phosphoric esters and partial sulfuric esters of a monohydroxy-functional polyalkylene ethers are those whose polyalkylene ether radicals can be prepared by oxalkylation of long-chain alcohols such as C₁₀-C₂₀-alkanols, preferably C₁₀-C₁₆-alkanols, with alkylene oxides such as ethylene oxide, propylene oxide or butylene oxide. The alkylene oxides can be employed as a mixture, or else successively, for preparing block copolymers.