Abstract:
A method of selectively controlling undesirable vegetation in crops by using a postemergent application of an herbicidally effective amount of a metal chelate of a 2-(substituted benzoyl)-1,3-cyclohexanedione compound to the locus of such undesirable vegetation.

Description:
FIELD OF THE INVENTION 
     The present invention is directed to the use of metal chelates as a delivery system to improve the selectivity of 2-(substituted benzoyl)-1,3-cyclohexanedione compounds as post-emergence herbicides in crops. 
     BACKGROUND OF THE INVENTION 
     The protection of crops from weeds and other undesirable vegetation which inhibit crop growth is a constantly recurring problem in agriculture. To help combat this problem researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical formulations effective in the control of such unwanted growth. Chemical herbicides of many types have been disclosed in the literature and a large number are in commercial use. 
     Unfortunately, many of such herbicides exhibit phytotoxicity to the desired crop as well as to the weeds sought to be controlled. Thus, there is a long-standing need for selective herbicides which will control frequently occurring weeds but which will not adversely affect the crop plants when applied at herbicidally effective levels. 
     U.S. Pat. Nos. 4,780,127, 4,938,796, 5,006,158 and 5,089,046 disclose 2-(substituted benzoyl)-1,3-cyclohexanedione compounds having the general structure:                           
     wherein X, Q and Z have the meanings set forth hereinafter. These dione compounds have proved to be effective pre-emergent and postemergent herbicides against a wide variety of grasses, broadleaf weeds and sedges. Moreover, PCT Application No. 97/27748 discloses that metal chelates of 2-(substituted benzoyl)-1,3-cyclohexanedione compounds have proved to be chemically stable for long periods of time under normal as well as extreme temperature conditions. 
     The parent cyclohexanedione exhibits a substantial phytotoxic effect. In contrast, it has now been discovered that metal chelates of 2-(substituted benzoyl)-1,3-cyclohexanedione compounds will effectively control a broad range of weeds without exhibiting any substantial phytotoxic effect on the crop itself. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to methods of selectively controlling weeds and other undesirable vegetation in a given crop such as wheat. In one embodiment of this invention, the method comprises the postemergent application of an herbicidally effective amount of a metal chelate of a 2-(substituted benzoyl)-1,3-cyclohexanedione to the locus of such weeds and other vegetation. In another embodiment of this invention, the method comprises the postemergent application of an herbicidally effective amount of a metal chelate of a 2-(substituted benzoyl)-1,3-cyclohexanedione to the locus of such weeds and other vegetation, said metal chelate having been formulated as a microcapsule. 
     As is employed herein, the term “herbicide” is used to denote a compound which controls or modifies the growth of plants. The term “herbicidally effective amount” is used to indicate the quantity of such compound which is capable of producing a controlling or modifying effect. Controlling or modifying effects include all deviations from natural development, for example: killing, retardation, leaf burn, albinism, dwarfing, and the like. The term “plants” refers to all physical parts of a plant, including seeds, seedlings, saplings, roots, tubers, stems, stalks, foliage, and fruits. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to the use of metal chelates of herbicidal dione compounds to selectively control weeds and other undesirable vegetation in a given crop such as wheat. These herbicidal dione compounds have the general formula (I):                           
     wherein X represents a halogen atom; a straight- or branched-chain alkyl or alkoxy group containing up to six carbon atoms which is optionally substituted by one or more groups —OR 1  or one or more halogen atoms; or a group selected from nitro, cyano, —CO 2  R 2 —S(O) m R 1 , —O(CH 2 ) m OR 1 , —COR 2 , —OSO 2 R 4 , —NR 2 R 3 , —SO 2 NR 2 R 3 , —CONR 2 R 3  and —CSNR 2 R 3 ; 
     R 1  represents a straight- or branched-chain alkyl group containing up to six carbon atoms which is optionally substituted by one or more halogen atoms; 
     R 2  and R 3  each independently represents a hydrogen atom; or a straight- or branched-chain alkyl group containing up to six carbon atoms which is optionally substituted by one or more halogen atoms; 
     R 4  represents a straight- or branched-chain alkyl, alkenyl or alkynyl group containing up to six carbon atoms optionally substituted by one or more halogen atoms; or a cycloalkyl group containing from three to six carbon atoms; 
     each Z independently represents halo, nitro, cyano, S(O) m R 5 , OS(O) m R 5 , (C 1 -C 6 )alkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )haloalkyl, (C 1 -C 6 )haloalkoxy, carboxy, (C 1 -C 6 )alkylcarbonyloxy, (C 1 -C 6 )alkoxycarbonyl, (C 1 -C 6 )alkylcarbonyl, amino, (C 1 -C 6 )alkylamino, (C 1 -C 6 )dialkylamino having independently the stated number of carbon atoms in each alkyl group, (C 1 -C 6 )alkylcarbonylamino, (C 1 -C 6 )alkoxycarbonylamino, (C 1 -C 6 )alkylaminocarbonylamino, (C 1 -C 6 )dialkylaminocarbonylamino having independently the stated number of carbon atoms in each alkyl group, (C 1 -C 6 )alkoxycarbonyloxy, (C 1 -C 6 )alkylaminocarbonyloxy, (C 1 -C 6 )dialkylaminocarbonyloxy, phenylcarbonyl, substituted phenylcarbonyl, phenylcarbonyloxy, substituted phenylcarbonyloxy, phenylcarbonylamino, substituted phenylcarbonylamino, phenoxy or substituted phenoxy; 
     R 5  represents cyano; —COR 6 ; —CO 2 R 6 ; or —S(O) m R 7 ; 
     R 6  represents hydrogen or straight- or branched-chain alkyl group containing up to six carbon atoms; 
     R 7  represents (C 1 -C 6 )alkyl, (C 1 -C 6 )haloalkyl, (C 1 -C 6 )cyanoalkyl (C 3 -C 8 )cycloalkyl optionally substituted with halogen, cyano or (C 1 -C 4 )alkyl; or phenyl optionally substituted with one to three of the same or different halogen, nitro, cyano, (C 1 -C 4 )haloalkyl, (C 1 -C 4  alkyl, (C 1 -C 4 )alkoxy or —S(O) m R 8 ; 
     R 8  represents (C 1 -C 4 )alkyl, (C 1 -C 4 )alkyl substituted with halogen or cyano, phenyl or benzyl; 
     each Q independently represents C 1 -C 4  alkyl or —CO 2 R 9  wherein R 9  is C 1 -C 4  alkyl; 
     m is zero, one or two; 
     n is zero or an integer from one to four; 
     r is one, two or three; and 
     z is 0 or an integer from 1 to 6. 
     As used herein, the terms “halogen” and “halo” include fluorine, chlorine, bromine and iodine atoms. In polyhalogenated groups, the halogens may be the same or different. The term “substituted” in terms of “substituted phenylcarbonyl,” “substituted phenylcarbonyloxy,” “substituted phenylcarbonylamino” and “substituted phenoxy” means having one to five substituents, which may be the same or different, selected from the following: halo, nitro, cyano, S(O) m R 2 , (C 1 -C 6 )alkyl, (C 1 -C 6 )alkoxy, (C 1 -C 6 )haloalkyl, (C 1 -C 6 )haloalkoxy, carboxy, (C 1 -C 6 )alkylcarbonyloxy, (C 1 -C 6 )alkylcarbonyl, (C 1 -C 6 )alkoxycarbonyl, (C 1 -C 6 )alkylcarbonylamino, amino, (C 1 -C 6 )alkylamino and (C 1 -C 6 )dialkylamino having independently the stated number of carbon atoms in each group. 
     The 2-(substituted benzoyl)-1,3-cyclohexanedione compounds of formula I are described, inter alia, in U.S. Pat. Nos. 4,780,127, 4,938,796, 5,006,158 and 5,089,046, the disclosures of which are incorporated herein by reference. Herbicidal 2-(substituted benzoyl)-1,3-cyclohexanedione compounds for use in this invention may be prepared by the methods described in the aforementioned patent publications, or by the application and adaptation of known methods used or described in the chemical literature. 
     2-(substituted benzoyl)-1,3-cyclohexanedione compounds especially useful in the present invention include those in which z is zero; X is chloro, bromo, nitro, cyano, C 1 -C 4  alkyl, —CF 3 , —S(O) m R 1  or —OR 1 ; n is one or two; and each Z is independently chloro, bromo, nitro, cyano, C 1 -C 4  alkyl, —CF 3 , —OR 1 , —OS(O) m R 5  or —S(O) m R 5 . Examples of preferred cyclohexanedione compounds are 2-(2′-nitro-4′-methylsulfonylbenzoyl)-1,3-cyclohexanedione, 2-(2′-nitro-4′-methylsulfonyloxybenzoyl)-1,3-cyclohexanedione and 2-(2′-chloro-4′-methylsulfonylbenzoyl)-1,3-cyclohexanedione. 
     Compounds of formula (I) may exist in enolic tautomeric forms that may give rise to geometric isomers. Furthermore, in certain cases, the various substituents may contribute to optical isomerism and/or stereoisomerism. All such forms are embraced within compounds useful in the present invention. 
     Metal chelates of 2-(substituted benzoyl)-1,3-cyclohexanedione compounds of formula I are described, inter alia, in PCT Application No. 97/27748, the disclosures of which are incorporated herein by reference. Metal chelates of 2-(substituted benzoyl)-1,3-cyclohexanedione compounds have the general structure:                           
     wherein X, Q and Z have the meanings set forth above, and Me represents a di- or trivalent metal ion such as Cu +2 , Co +2 , Zn +2 , Ni +2 , Ca +2 , Al +3 , Ti +3  and Fe +3 . 
     Herbicidal metal chelates of 2-(substituted benzoyl)-1,3-cyclohexanedione compounds for use in this invention may be prepared by the methods described in the aforementioned PCT application, or by the application and adaptation of known methods used or described in the chemical literature. 
     Metal ions which may be useful in forming the metal chelate compounds of the present invention include di- or trivalent metal ions such as Cu +2 , Co +2 , Zn +2 , Ni +2 , Ca +2 , Al +3 , Ti +3  and Fe +3 . The selection of a particular metal ion to form the metal chelate compound will depend upon the dione compound to be chelated and the strength of the metal chelate complex. Without being bound by theory, it appears as if the strength of the metal chelate complex is directly related to the release rate of the triketone from the metal chelate complex, which in turn is related to the selectivity of the metal chelate compounds of this invention. Those skilled in the art will be able to readily determine the appropriate metal ion for use with a specific dione compound without undue experimentation. The preferred metal ions are divalent transition metal ions, particularly Cu +2 , Ni +2 , Zn +2  and Co +2 , with Cu +2  being especially preferred. 
     Any appropriate salt which would be a source of a di- or trivalent metal ion may be used to form the metal chelate of the dione compound in accordance with this invention. Particularly suitable salts include: chlorides, sulfates, nitrates, carbonates, phosphates and acetates. 
     It also has been found that the stability and the activity of the herbicidal metal chelate compositions of the present invention is pH dependent. The pH of the metal chelate compositions should be between about 2 and about 10, preferably between about 3 and about 7. Generally, it is believed that for Cu +2  chelate compositions the pH should be between about 4 and 6; for Co +2  between about 3 and 5; and for Ni +2  and Zn +2  about 5. The optimum pH for a particular metal chelate composition can be determined using routine experimental techniques. 
     The metal chelate of the herbicidal 2-(substituted benzoyl)-1,3-cyclohexanedione compounds can be formulated in the same manner in which herbicides are generally formulated. The choice of formulation and mode of application for any given herbicidal compound may affect its activity, and selection must be made accordingly. Herbicidal compositions may thus be formulated as water dispersible granules, as wettable powders, as powders or dusts, as suspensions, or as controlled release forms such as microcapsules. The formulation of the metal chelate of the herbicidal 2-(substituted benzoyl)-1,3-cyclohexanedione compounds for use in this invention may be prepared by the methods described in the aforementioned patent application or by the application and adaptation of known methods used or described in the chemical literature. Processes for microencapsulating the herbicidal composition specifically have been described in U.S. Pat. Nos. 4,285,720 and 4,956,129 and U.S. application Ser. No. 08/354,409, and may also be prepared by the application and adaptation of known methods used or described in the chemical literature. The object of the formulation, however, is to apply the compositions to the locus where control is desired by a convenient method (i.e., postemergent application). The “locus” is intended to include soil, as well as established vegetation. 
     Formulations containing the metal chelates of the herbicidal dione compounds of formula (I) can be applied by conventional methods to the areas where control is desired. The formulations containing an herbicidal metal chelate according to the invention can also be produced as premixes with other herbicides, or can be tank-mixed with one or more additional herbicidal or other agricultural compositions. Specific examples of other herbicides which may be incorporated in an herbicidal formulation with the metal chelates according the invention include acetanilides, tralkoxydim, bromoxynil and its esters, thiafluamide, MCPA and its esters, 2,4-D and its esters, and fluroxypyr meptyl. 
     In the practice of the present invention, the metal chelate of the herbicidal 2-(substituted benzoyl)-1,3-cyclohexanedione compounds is applied postemergent to the locus of the undesirable vegetation to be controlled. Application rates will depend on the particular plant species and degree of control desired. In general, application rates of between about 5 and about 500 g/ha may be employed. 
    
    
     The following examples are for illustrative purposes only and are not intended as necessarily representative of the overall testing performed and are not intended to limit the invention in any way. 
     SPECIFIC EMBODIMENTS OF THE INVENTION 
     Example 1 
     All of the metal chelate compounds used in the 1,3-cyclohexanedione formulations of this example were prepared using a mix and mill process except for Formulation C which was formulated using a precipitation process. Both the mix and mill process and the precipitation process are described in more detail in PCT Application Ser. No. 97/27748, the disclosure of which has been incorporated herein by reference. 
     Twelve days after the seeds were sown in aluminum flats (containing soil comprising 2 parts sandy loam to 1 part peat), the 1,3-cyclohexanedione suspension formulations (at the rates listed in Table I below) were applied postemergence to the following plant species:  Galium aparine  (catchweed bedstraw) (“GALAP”);  Chenopodium album  (lambsquarters) (“CHEAL”);  Matricaria inodora  (scentless flase chamomile) (“MATIN”); and wheat. 
     The flats were placed in a greenhouse and evaluated 6 and 21 days after application (“DAA”). Injury was evaluated as percent control, with percent control being the total injury to the plants due to all factors including: Inhibited emergence, stunting, malformation, albinism, chlorisis, and other types of plant injury. The control rating range from 0 to 100 percent, where 0% represents no effect with growth equal to the untreated control and where 100% represents a complete kill. 
     The results observed (as a mean of 3 replications) are summarized in Table I below. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE I 
               
             
             
               
                   
               
               
                 Bioactivity of Various Metal Chelates of 1,3-Cyclohexanedione Formulations 
               
             
          
           
               
                   
                 Phytotoxicity 
                 Weed Control Activity, % 
               
             
          
           
               
                   
                 Molar Ratio 
                 Appl. Rate 
                 to Wheat, % 
                 GALAP 
                 CHEAL 
                 MATIN 
               
             
          
           
               
                 Formulation 
                 Dione/Metal 
                 g a.i./ha 
                 6 days 
                 21 days 
                 21 days 
                 21 days 
                 21 days 
               
               
                   
               
             
          
           
               
                 Control 1 (Unchelated) 
                   
                 12.5 
                 38 
                 10 
                 75 
                 100 
                 99 
               
               
                   
                   
                 25 
                 45 
                 14 
                 54 
                 100 
                 100 
               
               
                   
                   
                 50 
                 53 
                 22 
                 99 
                 100 
                 100 
               
               
                   
                   
                 100 
                 65 
                 58 
                 100 
                 100 
                 100 
               
               
                 Formulation A 
                 2/5 
                 12.5 
                 0 
                 0 
                 64 
                 100 
                 0 
               
               
                 (Cu Chelate) 
                   
                 25 
                 2 
                 0 
                 75 
                 100 
                 44 
               
               
                   
                   
                 50 
                 2 
                 0 
                 83 
                 100 
                 72 
               
               
                   
                   
                 100 
                 2 
                 4 
                 98 
                 100 
                 85 
               
               
                 Formulation B 
                 2/1 
                 12.5 
                 0 
                 0 
                 83 
                 100 
                 18 
               
               
                 (Cu Chelate) 
                   
                 25 
                 2 
                 0 
                 87 
                 100 
                 45 
               
               
                   
                   
                 50 
                 0 
                 0 
                 84 
                 100 
                 73 
               
               
                   
                   
                 100 
                 2 
                 6 
                 99 
                 100 
                 90 
               
               
                 Formulation C 
                 2/1 
                 12.5 
                 0 
                 0 
                 93 
                 100 
                 84 
               
               
                 (Cu Chelate) 
                   
                 25 
                 0 
                 0 
                 94 
                 100 
                 79 
               
               
                   
                   
                 50 
                 0 
                 0 
                 68 
                 100 
                 100 
               
               
                   
                   
                 100 
                 8 
                 7 
                 99 
                 100 
                 100 
               
               
                 Formulation D 
                 2/5 
                 12.5 
                 5 
                 0 
                 44 
                 100 
                 100 
               
               
                 (Co Chelate) 
                   
                 25 
                 8 
                 2 
                 61 
                 100 
                 88 
               
               
                   
                   
                 50 
                 25 
                 10 
                 84 
                 100 
                 55 
               
               
                   
                   
                 100 
                 33 
                 14 
                 100 
                 100 
                 99 
               
               
                 Formulation E 
                 2/1 
                 12.5 
                 23 
                 2 
                 63 
                 100 
                 99 
               
               
                 (Co Chelate) 
                   
                 25 
                 33 
                 2 
                 66 
                 100 
                 100 
               
               
                   
                   
                 50 
                 38 
                 20 
                 94 
                 100 
                 100 
               
               
                   
                   
                 100 
                 43 
                 38 
                 99 
                 100 
                 100 
               
               
                 Formulation F 
                 2/5 
                 12.5 
                 20 
                 2 
                 66 
                 100 
                 100 
               
               
                 (Zn Chelate) 
                   
                 25 
                 28 
                 8 
                 71 
                 100 
                 100 
               
               
                   
                   
                 50 
                 35 
                 17 
                 99 
                 100 
                 93 
               
               
                   
                   
                 100 
                 40 
                 18 
                 98 
                 100 
                 100 
               
               
                 Formulation G 
                 2/1 
                 12.5 
                 28 
                 3 
                 64 
                 100 
                 65 
               
               
                 (Zn Chelate) 
                   
                 25 
                 35 
                 10 
                 89 
                 100 
                 99 
               
               
                   
                   
                 50 
                 40 
                 19 
                 84 
                 100 
                 100 
               
               
                   
                   
                 100 
                 45 
                 35 
                 100 
                 100 
                 100 
               
               
                 Formulation H 
                 2/5 
                 12.5 
                 20 
                 3 
                 85 
                 100 
                 100 
               
               
                 (Ni Chelate) 
                   
                 25 
                 30 
                 3 
                 59 
                 100 
                 100 
               
               
                   
                   
                 50 
                 40 
                 9 
                 100 
                 100 
                 100 
               
               
                   
                   
                 100 
                 45 
                 31 
                 98 
                 100 
                 100 
               
               
                 Formulation I 
                 2/5 
                 12.5 
                 30 
                 6 
                 78 
                 100 
                 100 
               
               
                 (Ca Chelate) 
                   
                 25 
                 40 
                 9 
                 83 
                 100 
                 100 
               
               
                   
                   
                 50 
                 45 
                 25 
                 100 
                 100 
                 100 
               
               
                   
                   
                 100 
                 53 
                 48 
                 94 
                 100 
                 100 
               
               
                   
               
             
          
         
       
     
     From these results, it is clear that the phytotoxicity of the 1,3-cyclohexanedione formulations to wheat was reduced by chelation. In contrast, however, the herbicidal activity of the 1,3-cyclohexanedione formulations on the weeds and other undesirable vegetation was only slightly affected by chelation. In addition, it is also apparent from these results that the activity of the 1,3-cyclohexanedione formulation varied depending on the metal ion used to form the metal chelate compound. 
     Example 2 
     The metal chelate compounds used in the 1,3-cyclohexanedione suspension formulations of this example were prepared using the mix and mill process as described in Example 1. Moreover, a procedure essentially identical to that described in Example 1 was employed for the postemergent application of the 1,3-cyclohexanedione suspension formulations (at the rates listed in Table II below) to aluminum flats containing the following plant species: CHEAL;  Amaranthus retroflexus  (redroot pigweed)(“AMARE”);  Polygonum convolvulus  (wild buckwheat)(“POLCO”);  Brassica kaber  (wild mustard)(“SINAR”);  Thlaspi arventse  (field pennycress)(“THLAR”);  Brassica canpestris  (oilseed rape)(“BRSNN”); wheat (“TRZAS”); and barley (“HORVS”). Injury was evaluated at 8 and 32 DAA. 
     The results observed (as a mean of 4 replications) are summarized in Table II below. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE II 
               
             
             
               
                   
               
               
                 Comparison of Activity and Phytotoxicity of Chelated and Unchelated 1,3-Cyclohexanedione (a.i.) Formulations 
               
             
          
           
               
                   
                 Phytotoxicity to 
                   
               
               
                   
                 Wheat (TRZAS) and 
               
               
                   
                 Barley (HORVS), % 
                 Weed Control Activity, % (32 days) 
               
             
          
           
               
                   
                 Rate 
                 TRZAS 
                 HORVS 
                 AMARE 
                 BRSNN 
                 CHEAL 
                 POLCO 
                 SINAR 
                 THLAR 
               
             
          
           
               
                 Formulation 
                 g a.i./ha 
                 8 days 
                 32 days 
                 8 days 
                 32 days 
                 32 days 
                 32 days 
                 32 days 
                 32 days 
                 32 days 
                 32 days 
               
               
                   
               
             
          
           
               
                 Control 2 
                 3.125 
                 4 
                 1 
                 0 
                 0 
                 80 
                 69 
                 100 
                 4 
                 92 
                 85 
               
               
                 (Unchelated) 
                 6.25 
                 14 
                 5 
                 4 
                 0 
                 88 
                 86 
                 100 
                 53 
                 99 
                 91 
               
               
                   
                 12.5 
                 19 
                 1 
                 6 
                 0 
                 97 
                 89 
                 100 
                 81 
                 98 
                 99 
               
               
                   
                 25 
                 24 
                 12 
                 6 
                 0 
                 98 
                 97 
                 100 
                 94 
                 97 
                 100 
               
               
                   
                 50 
                 34 
                 15 
                 11 
                 4 
                 100 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                   
                 100 
                 44 
                 59 
                 18 
                 6 
                 100 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                 Formulation J 
                 6.25 
                 0 
                 0 
                 0 
                 1 
                 100 
                 90 
                 100 
                 100 
                 100 
                 99 
               
               
                 (Cu Chelate) 
                 12.5 
                 0 
                 0 
                 0 
                 1 
                 98 
                 82 
                 100 
                 98 
                 99 
                 94 
               
               
                   
                 25 
                 0 
                 0 
                 0 
                 0 
                 99 
                 89 
                 100 
                 66 
                 100 
                 99 
               
               
                   
                 50 
                 0 
                 0 
                 0 
                 1 
                 100 
                 89 
                 100 
                 88 
                 100 
                 100 
               
               
                   
                 100 
                 4 
                 34 
                 1 
                 3 
                 100 
                 95 
                 100 
                 100 
                 100 
                 100 
               
               
                   
                 200 
                 11 
                 64 
                 0 
                 4 
                 100 
                 100 
                 100 
                 100 
                 99 
                 100 
               
               
                   
               
             
          
         
       
     
     These data indicate that the copper chelate of 2-(substituted benzoyl)-1,3-cyclohexanedione, Formulation J, showed an 16X increase in wheat selectivity at early assessment compared to the unchelated formulation (Control 2). Weed control activity of the copper chelate formulation was approximately the same as that of the unchelated formulation. 
     Example 3 
     The metal chelate compounds used in the 1,3-cyclohexanedione formulations of this example were prepared using the mix and mill process as described in Example 1. Control 3 and Formulation K were formulated as suspension formulations and Formulation L was formulated as microcapsules. 
     Employing a procedure essentially identical to that described in Example 1, the 1,3-cyclohexanedione formulations were applied postemergence at the rates listed in Table III below to aluminum flats containing the following plant species: AMARE, BRSNS, POLCO, SINAR and TRZAS. Injury was evaluated at 6 and 22 DAA. 
     The results observed (as a mean of 4 replications) are summarized in Table III below. 
     
       
         
               
             
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE III 
               
             
             
               
                   
               
               
                 Comparison of Activity and Phytotoxicity of Unchelated, 
               
               
                 Chelated and Microencapsulated 1,3-Cyclohexandedione (a.i.) Formulations 
               
             
          
           
               
                   
                 Phytotoxicity to Wheat, % 
                 Weed Control Activity, % 
               
             
          
           
               
                   
                 Rate 
                 TRZAS(K) 
                 TRZAS(R) 
                 AMARE 
                 BRSNN 
                 POLCO 
                 SINAR 
               
             
          
           
               
                 Formulation 
                 g a.i./ha 
                 6 days 
                 22 days 
                 6 days 
                 22 days 
                 22 days 
                 22 days 
                 22 days 
                 22 days 
               
               
                   
               
             
          
           
               
                 Control 3 
                 2.5 
                 — 
                 — 
                 — 
                 — 
                 56 
                 38 
                 48 
                 87 
               
               
                 (Unchelated) 
                 5 
                 — 
                 — 
                 — 
                 — 
                 85 
                 48 
                 65 
                 85 
               
               
                   
                 10 
                 — 
                 — 
                 — 
                 — 
                 90 
                 81 
                 83 
                 97 
               
               
                   
                 20 
                 23 
                 10 
                 26 
                 8 
                 97 
                 88 
                 97 
                 100  
               
               
                   
                 40 
                 29 
                 9 
                 40 
                 18 
                 99 
                 96 
                 88 
                 100  
               
               
                   
                 80 
                 34 
                 18 
                 50 
                 25 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                 160 
                 60 
                 58 
                 58 
                 59 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                 320 
                 61 
                 80 
                 61 
                 80 
                 — 
                 — 
                 — 
                 — 
               
               
                 Formulation K 
                 2.5 
                 — 
                 — 
                 — 
                 — 
                 41 
                 65 
                 55 
                 97 
               
               
                 (Cu Chelate) 
                 5 
                 — 
                 — 
                 — 
                 — 
                 72 
                 56 
                 67 
                 92 
               
               
                   
                 10 
                 — 
                 — 
                 — 
                 — 
                 61 
                 65 
                 62 
                 93 
               
               
                   
                 20 
                 4 
                 3 
                 16 
                 14 
                 88 
                 73 
                 89 
                 95 
               
               
                   
                 40 
                 10 
                 17 
                 6 
                 31 
                 97 
                 90 
                 92 
                 96 
               
               
                   
                 80 
                 0 
                 8 
                 12 
                 21 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                 160 
                 6 
                 33 
                 7 
                 33 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                 320 
                 39 
                 74 
                 49 
                 69 
                 — 
                 — 
                 — 
                 — 
               
               
                 Formulation L 
                 2.5 
                 — 
                 — 
                 — 
                 — 
                 20 
                 39 
                 25 
                 88 
               
               
                 (Cu Chelate/ 
                 5 
                 — 
                 — 
                 — 
                 — 
                 26 
                 10 
                 28 
                 78 
               
               
                 Microcapsule) 
                 10 
                 — 
                 — 
                 — 
                 — 
                 45 
                 16 
                 45 
                 88 
               
               
                   
                 20 
                 1 
                 1 
                 6 
                 5 
                 75 
                 31 
                 66 
                 99 
               
               
                   
                 40 
                 0 
                 3 
                 1 
                 6 
                 95 
                 71 
                 84 
                 98 
               
               
                   
                 80 
                 1 
                 13 
                 0 
                 10 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                 160 
                 0 
                 38 
                 4 
                 33 
                 — 
                 — 
                 — 
                 — 
               
               
                   
                 320 
                 39 
                 66 
                 15 
                 58 
                 — 
                 — 
                 — 
                 — 
               
               
                   
               
             
          
         
       
     
     The above data indicates that the copper chelate of 2-(substituted benzoyl)-1,3-cyclohexanedione (Formulation K) showed improved selectivity over the unchelated formulation (Control 3). These data also indicate that the selectivity of the copper chelate of 2-(substituted benzoyl)-1,3-cyclohexanedione was further improved by microencapsulation (Formulation L). 
     The foregoing description and example are for the purpose of illustration only and does not limit the scope of protection which should be accorded this invention.