Abstract:
There is provided a method for enhancing the control of monocotyledenous and dicotyledenous plant species comprising applying to said plant species a combination of optically active R-imidazolinone compounds. Also provided is a herbicidal composition comprising a combination of R-imidazolinone compounds.

Description:
This application claims the benefit of Provisional Application No. 60/063,915 filed Oct. 31, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     Imidazolinone compounds and their herbicidal use are described in U.S. Pat. No. 4,798,619. Combinations of racemic imidazolinone compounds and their synergistic herbicidal effect are described in U.S. Pat. No. 5,030,271. The R and S optical isomers of imidazolinone compounds and their relative individual herbicidal effect are described in The Imidazolinone Herbicides, CRC Press, Inc. (1991). 
     In view of the imidazolinone art, in general, one would expect the R isomer of an imidazolinone compound to have a herbicidal effect of approximately 1.5-1.8 times greater than that of the corresponding racemic imidazolinone compound. Therefore, to the extent the combination of R-imidazolinone compounds behave as the combination of racemic imidazolinone compounds, one would expect a combination of R-imidazolinone compounds to demonstrate about a 1.5-1.8 times greater herbicidal effect than the corresponding combination of racemic imidazolinone compounds. 
     SUMMARY OF THE INVENTION 
     It has now been found, that combinations of the optically active R isomers of imidazolinone compounds such as R-imazethapyr and R-imazapyr demonstrate a surprisingly enhanced herbicidal effect when compared to the herbicidal effect of the corresponding combination of racemic compounds, as well as when compared to the herbicidal effect of the individual optically active R-imidazolinone components. 
     The present invention provides a method for enhancing the control of undesirable monocotyledenous and dicoty-ledenous plant species which comprises applying to the foliage of said plants or to the soil or water in which the seeds, tubers or other propagating organs thereof are growing or to he grown an effective amount of a combination of the R isomer of an imidazolinone compound plus the R isomer of a second different imidazolinone compound such as a combination of R-imazethapyr plus R-imazapyr. 
     The present invention also provides a herbicidal composition which comprises an inert liquid or solid carrier and an effective amount of a combination of R-imidazolinone compounds, such as a combination of R-imazethapyr plus, R-imazapyr. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A constant concern in crop production is how to efficiently control weed competition with responsible ecological practices. One effective tool currently available to agriculturalists is the imidazolinone family herbicides. These compounds offer a mode of action which targets an enzyme which is only present in plants. Therefore, they are non-harmful to all non-plant life such as humans, animals, birds, fish and the like. Further, imidazolinone herbicides are effective at relatively low application rates. However, since they have a broad spectrum of weed control, and therefore, a variety of application uses, a new means of lowering the use rates needed to control weeds and diminishing the environmental load of active ingredient is desirable. 
     Surprisingly, it has now been found that the application of a combination of the R-isomer of one imidazolinone, or the salt thereof, with the R-isomer of another different imidazolinone, or the salt thereof, provides enhanced control of undesirable monocotyledenous and dicotyledenous plant species. The combination of R-imidazolinone compounds, or their salts, may be applied to the foliage or the soil or water in which the seeds, tubers or other propagating organs of said plant species are growing or are to be grown, preferably to the foliage. Advantageously, combinations of R-imidazolinones such as R-imazethapyr plus R-imazapyr, or the salts thereof demonstrate increased maize selectivity, particularly imidazolinone resistant or imidazolinone tolerant maize selectivity. 
     As used in the specification and claims, the term R-imidazolinone designates the optical isomer of an imidazolinone Compound having the R configuration assigned to the asymmetric carbon in the imidazolinone ring which is substituted by a methyl and an isopropyl group, for example an imidazolinone compound having the structure of formula I ##STR1## wherein R is H, or a cation; and 
     Y and Z are each independently H, C 1  -C 4  alkyl optionally substituted with C 1  -C 4  alkoxy or Y and Z may be taken together to represent --CH═CH--CH═CH--. 
     Examples of R-imidazolinone compounds of formula I useful in the method and composition of the invention include R-imazapyr, R-imazethapyr, R-imazaquin, R-imazamox, R-imazapic, and the like or a salt thereof, preferably R-imazethapyr and R-imazapyr or a salt thereof. 
     A cation, as used in the specification and claims, designates a positively charged moiety such as an alkali metal, an alkaline earth metal, ammonium, organic ammonium, manganese, copper, iron, zinc, cobalt, lead, silver, nickel and the like. Preferable cations are alkali metals, alkaline earth metals, ammonium or organic ammonium. Organic ammonium designates a positively charged nitrogen atom having one to four organic groups attached, such as alkyl, aryl or heteroaryl. The organic group may be cyclic or acyclic and may incorporate the positively charged nitrogen atom within the ring or without the ring. Preferable organic groups are alkyl groups such as isopropyl. 
     It is especially surprising that combinations comprising R-imatzethapyr plus R-imazapyr (or their salts) in a ratio of about 3 parts R-imazethapyr to one part R-imazapyr demonstrate a 2×-3× increase in weed control when compared to the corresponding combination of racemic imazethapyr plus racemic imazapyr (or their salts). 
     Advantageously, the method of invention may be used to enhance weed control at varied sites such as industrial, agricultural, recreational, ornamental and the like. In the instance of agricultural weed control, the method of invention is suitable for use in the presence of crop plant species and particularly in the presence of imidazolinone resistant or tolerant crop species such as legumes (e.g. peanuts or soybeans), IMI-CORN™, IMI™ canola, IMI™ wheat, IMI™ cotton, IMI™ rice and the like, especially IMI-CORN™. 
     The effective amount of the combination of R-imidazolinone compounds will vary according to the prevailing conditions such as weather, plant species, weed pressure, growth stage, mode of application, cultivation practice and the like. Generally effective amounts of a combination of R-imidazolinone compounds such as R-imazethapyr plus R-imazapyr may be about 0.003 kg/ha-0.250 kg/ha of R-imazethapyr plus about 0.001 kg/ha-0.083 kg/ha of R-imazapyr, preferably about 0.025-0.100 kg/ha of R-imazethapyr plus about 0.008-0.035 kg/ha of R-imazapyr. 
     In actual agricultural practice, the combination of R-imidazolinone compounds such as R-imazethapyr plus R-imazapyr may be applied simultaneously as a tank-mix partner or a co-formulant or sequentially as a separate application, preferably as a tank-mix partner or co-formulant. Therefore, the present invention also provides a herbicidal composition comprising an inert liquid or solid carrier and an effective amount of a combination of an R-imidazolinone compound plus a second different R-imidazolinone compound such as R-imazethapyr plus R-imazapyr or the salts thereof. Preferably, the R-imazethapyr and R-imazapyr, or their salts, are present in a ratio of about three parts of R-imazethapyr to one part R-imazapyr. Compositions of the invention include soluble granules, aqueous concentrates, dispersible granules, wettable powders, and the like, preferably soluble granules, aqueous concentrates or dispersible granules. 
     The agriculturally acceptable carrier may be a solid or liquid. Suitable solid carriers may be any inert carrier commonly used such as natural and synthetic clays and silicates, natural and synthetic resins, solid fertilizers and the like. Typical examples of a solid carrier include diatomaceous earth, talc, attapulgite, vermiculite, kaolinite, mica, calcium sulphate, silicon oxide, coumarone resin, polyvinyl chloride, styrene and the like. Similarly, suitable liquid carriers include water, glycols, alcohols, ketones, ethers, aromatic or araliphatic hydrocarbons, petroleum fractions, and the like, or mixtures thereof. Preferred carriers are water soluble carriers. 
    
    
     For a more clear understanding of the invention, specific examples thereof are set forth below. These examples are merely illustrative and are not to be understood as limiting the scope and underlying principles of the invention in any way. Indeed, various modifications of the invention, in addition to those shown and described herein, will become apparent to those skilled in the art from the following examples and foregoing description. Such modifications are also intended to fall within the scope of the appended claims. 
     EXAMPLE 1 
     Evaluation of the Enhanced Herbicidal Effect of the Combination of ohe R-Isomers of Imazethapyr and Imazapyr as Measured by Weed Control 
     In this evaluation, plants are grown in standard greenhouse soil for 10-14 days until they are at the 2- to 4-leaf stage. Said plants are then sprayed with an aqueous solution of the test compounds which contains 0.25% of a non-ionic surfactant and 1% of a 28-0-0 liquid fertilizer. Each treatment is replicated 3 to 4 times. Approximately 3 weeks after treatment visual ratings are made using the rating scale shown below. The data are averaged and shown on Table I. 
     
         ______________________________________Test Compound       Source______________________________________Imazethapyr         PURSUIT ®AS.sup.1Imazapyr            ARSENAL ®AS.sup.1Imazethapyr &amp; Imazapyr               LIGHTNING ® AS.sup.1R-imazethapyr       technical material.sup.2R-imazapyr          technical material.sup.2______________________________________ .sup.1 Manufactured by American Cyanamid Co. .sup.2 Formulated as an aqueous concentrate as described in U.S. 4,816,060. 
    
     
         ______________________________________Rating Scale      % ControlRating     (As Compared To Check)______________________________________9          1008          91-997          80-906          65-795          45-644          30-443          16-292           6-151          1-50          No Effect______________________________________ 
    
     
         ______________________________________PLANT SPECIESBayerCode       Scientific Name  Common Name______________________________________CHEAL      Chenopodium album, L.                       LambsquartersAMBEL      Ambrosia artemisiifolia, L.                       RagweedSETVI      Setaria viridis, (L) Beauv                       Green FoxtailABUTH      Abutilon theophrasti, Medic.                       Velvetleaf______________________________________ 
    
     
                       TABLE I______________________________________Rate           WEED CONTROLCompound   g/ha       CHEAL   AMBEL  SETVI ABUTH______________________________________Imazethapyr   4.00       2.5     2.5    3.5   2.5   8.00       2.3     2.8    4.5   3.0   16.00      3.5     4.0    4.3   4.0   32.00      7.0     6.0    6.0   6.3   64.00      8.0     6.5    7.5   6.3   96.00      9.0     7.5    9.0   9.0   128.00     9.0     8.8    9.0   9.0R-Imazetha-   2.68       2.3     3.8    4.8   4.8pyr     5.36       3.8     3.5    4.5   4.8   10.72      4.0     3.0    5.5   4.8   21.44      6.8     4.8    6.5   6.8   42.88      7.0     6.5    7.5   7.0   64.30      9.0     8.8    9.0   9.0   85.76      9.0     9.0    9.0   9.0Imazapyr   2.016      6.3     2.5    5.3   4.8   4.00       8.0     4.0    6.8   6.3   8.00       8.8     5.0    9.0   7.5   16.00      9.0     7.0    9.0   8.5   32.00      9.0     7.8    9.0   9.0   48.00      9.0     8.8    9.0   9.0   64.00      9.0     8.8    9.0   9.0R-Imazapyr   1.34       7.3     1.5    6.0   4.3   2.68       7.8     4.5    7.5   5.8   5.36       8.3     5.0    8.0   7.3   10.72      9.0     6.3    9.0   8.0   21.44      9.0     7.5    9.0   9.0   32.16      9.0     9.0    9.0   9.0   42.88      9.0     8.5    9.0   9.0Imazethapyr   3.02 + 1.0 4.3     2.5    3.0   4.5plus    6.0 + 2.0  6.5     3.3    6.0   4.8Imazapyr   12.0 + 4.0 7.5     5.5    7.3   6.8   24.0 + 8.0 8.5     6.8    8.8   7.5   48 + 16    8.8     7.5    9.0   8.8   72 + 24    9.0     8.3    9.0   9.0   96 + 32    9.0     9.0    9.0   9.0R-Imazetha-   2.01 + 0.67              5.3     4.3    5.5   5.5pyr plus   4.02 + 1.34              9.0     5.5    7.3   7.3R-Imazapyr   8.04 + 2.68              8.8     6.3    8.8   7.5   16.08 + 5.36              9.0     7.3    9.0   9.0   32.16 + 10.72              9.0     8.0    9.0   9.0   48.24 + 16.08              9.0     8.8    9.0   9.0   64.32 + 21.44              9.0     9.0    9.0   9.0______________________________________ 
    
     EXAMPLE 2 
     Evaluation of the Enhanced Herbicidal Effect of the Combination of the R-Isomers of Imazethapyr and Imazapyr as Measured by Fresh Weight 
     In this evaluation, plants are grown in standard greenhouse soil for 10-14 days until they are at the 2- to 4-leaf stage. Said plants are then sprayed with an aqueous solution of the test compounds which contains 0.25% of a non-ionic surfactant and 1% of a 28-0-0 liquid fertilizer. Test compounds used and the source thereof are the same as that described in Example 1. Each treatment is replicated 3 to 4 times. Approximately 3 weeks after treatment the plants are cut at the surface of the soil and weighed. The weights are reported as % of untreated check. The data are used to determine the rate at which a 50% plant growth inhibition as compared to the untreated check is obtained in grams per hectare. This rate is reported as the I 50  value. The I 50  values are calculated using the method described by Seefeldt, Jensen and Fuerst, Weed Technology, Vol. 9, p. 218-227 (1995). The I 50  values for the racemic test compounds and their corresponding R-isomers are compared and the ratio of I 50  -racemic/I 50  -R-isomer is recorded. The test results are shown in Table I, wherein the % fresh weight data are averaged. 
     
         ______________________________________PLANT SPECIESBayerCode       Scientific Name  Common Name______________________________________IPOSS      Ipomoea spp.     MorninggloryAMBEL      Ambrosia artemisiifolia, L.                       Ragweed______________________________________ 
    
     
                                           TABLE II__________________________________________________________________________IMAZETHAPYR    R-IMAZETHAPYR  IMAZPAYRRate  % Fresh Wt.          Rate  % Fresh Wt.                         Rate  % Fresh Wt.g/ha  IPOSS     AMBEL          g/ha  IPOSS                    AMBEL                         g/ha  IPOSS                                   AMBEL__________________________________________________________________________ 4.00 76  92   2.68  82  51   2.02  69  95 8.00 76  79   5.36  82  81   4.00  60  61 16.00 69  60   10.72 67  65   8.00  33  44 32.00 59  37   21.44 69  49   16.00 20  16 64.00 47  29   42.88 51  33   32.00 16  4 96.00 27  5    64.30 20  3    48.00 13  1128.00 25  2    85.76 16  0    64.00 12  1I.sub.50 35.0     22.0       32.2                    17.9       3.21                                   6.16(g/ha)Ratio  Racemic/R      ##STR2##                     ##STR3##                                    ##STR4##__________________________________________________________________________          RACEMIC        R-ISOMERR-IMAZAPYR     COMBINATION.sup.1                         COMBINATION.sup.2Rate  % Fresh Wt.          Rate  % Fresh Wt.                         Rate  % Fresh Wt.g/ha  IPOSS     AMBEL          g/ha  IPOSS                    AMBEL                         g/ha  IPOSS                                   AMBEL__________________________________________________________________________          3.0            2.011.34  76  111  1.0   69  103  0.67  70  84          6.0            4.022.68  57  76   2.0   63  92   1.34  68  57          12.0           8.045.36  33  56   4.0   64  53   2.68  45  36          24.0           16.0810.72 27  30   8.0   53  36   5.36  29  12          48.0           32.1621.44 17  7    16.0  37  21   10.72 20  6          72.0           48.2432.16 11  2    24.0  20  2    16.08 18  2          96.0           64.3242.88 13  4    32.0  18  0    21.44 18  3Ig.sub.50 2.12     5.94       15.2                    20.5       5.60                                   6.60(g/ha)Ratio  Racemic/R      ##STR5##                 ##STR6##                                ##STR7##__________________________________________________________________________ .sup.1 Imazethapyr plus imazapyr .sup.2 Rimazethapyr plus Rimazapyr 
    
     EXAMPLE 3 
     Field Evaluation of the Enhanced Herbicidal Effect of the Combination of the R-Isomers of Imazethapyr and Imazapyr 
     In this evaluation, small field plots having an average size of 3M×25M are used. All treatments are applied using a backpack sprayer. Test applications are made 19 days after planting a variety of weed species and IMI™-tolerant maize crops. Commercially available formulations of the test compounds are used where available. All combination treatments are tank-mixed prior to application. All treatments contain 0.25% of a nonionic surfactant and 1.0% of a 28-0-0 liquid fertilizer. Approximately 8 weeks after treatment, the plants are evaluated visually and % weed control is recorded. The data obtained are shown in Table III. Three varieties of IMI™-tolerant maize were used in this evaluation. At 8 weeks after treatment, no injury, such as stunting or chlorosis, was observed for all 3 varieties of maize. 
     
         ______________________________________Test Compound      Source______________________________________Imazethapyr        PURSUIT ®240 AS.sup.1Imazapyr              ARSENAL ®240 AS.sup.1R-imazethapyr      technical material.sup.2R-imazapyr         technical material.sup.2______________________________________ .sup.1 Manufactured by American Cyanamid Co. .sup.2 Formulated as an aqueous concentrate as described in U.S. 4,816,060. 
    
     
         ______________________________________PLANT SPECIESBayerCode   Scientific Name     Common Name______________________________________BIDPI  Bidens pilosa L.    Beggartick, HairyCASOC  Cassia occidentalis Coffee sennaHELAV  Helianthus annuus, L.                      SunflowerDEDTO  Desmodium tortuosum, (SW)DC.                      Beggarweed, FloridaBOILF  Borreria latifolia, Schum.                      Buttonweed, broadleafIAQGR  Ipomoea grandifolia MorningglorySETGE  Setaria geniculata (Lam.)P. Beauv.                      Foxtail, knotrootBRAPL  Brachiaria plantaginea (Link)Hitche.                      AlexandergrassDIGHO  Digitaria horizontalis, Wiild.                      CrabgrassCCHEC  Cenchrus echinatus, L.                      Sandbur, SouthernPANMA  Panicum maximum, Jacq.                      Guineagrass______________________________________ 
    
     
                                           TABLE III__________________________________________________________________________       RATETREATMENT   g/ha  BIDPI                 CASOC                     HELAV                         DEDTO                             BOILF                                 IAQGR                                     SETGE                                         BRAPL                                             DIGHO                                                 CCHEC                                                     PANMA__________________________________________________________________________Imazethapyr + Imazapyr       12 + 4             10  20  10  0   20  10  10  5   30  10  10       24 + 8             20  40  30  10  25  25  30  20  50  20  20       48 + 16             70  60  70  40  50  50  60  40  75  70  70       96 + 32             100 90  100 60  90  85  95  90  97  95  90R-Imazethapyr +         8 + 2.7             20  40  25  10  40  30  20  10  30  10  20R-Imazapyr   16 + 5.3             40  60  70  30  60  50  35  20  80  25  30       24 + 8             90  75  80  50  70  70  90  90  90  90  70         32 + 10.7             100 80  90  70  80  90  90  95  97  95  90         64 + 21.3             100 95  100 90  95  100 100 100 100 100 100__________________________________________________________________________ 
    
     EXAMPLE 4 
     Field Evaluation of the Enhanced Herbicidal Effect of the Combination of the R-Isomers of Imazethapyr and Imazapyr 
     In this evaluation, small field plots (10M×2M) in which imidazolinone resistant (IR) corn plants have been sown are used. All treatments are applied, using a CO 2  sprayer, approximately 3 weeks after planting and are replicated 3 times. Commercially available formulations of test compounds are used where available. All treatments contain 0.25% of a nonionic surfactant and 1% of a 28-0-0 liquid fertilizer. At 27 and 62 days after treatment (DAT) visual observation of % weed control and % stunting are recorded. The data obtained are shown in Table IV. 
     
         ______________________________________Test Compound       Source______________________________________Imazethapyr + Imazapyr               PURSUIT ® 240 AS.sup.1 +               ARSENAL ® 240 AS.sup.1R-imazethapyr + R-imazapyr               technical material.sup.2______________________________________ .sup.1 Manufactured by American Cyanamid Co. .sup.2 Formulated as an aqueous concentrate as described in U.S. 4,816,060. 
    
     
         ______________________________________PLANT SPECIESBayerCode   Scientific Name     Common Name______________________________________ANVCR  Anoda cristada, (L) Schlecht.                      Spurred anodaDIGSA  Digitaria, Sanguinalis, (LL) Scop.                      CrabgrassELEIN  Eleusine indica, (L) Gaertn.                      GoosegrassPOROL  Portulaca oleracea, (L)                      PurslaneSORHAP Sorghum halepense (L) Pers.                      Johnsongrass, rhizome______________________________________ 
    
     
                                           TABLE IV__________________________________________________________________________              % WEED CONTROL              %              ANVCR DIGSA ELEIN                               POROL SORHAP                                          Stunting        RATE  (Days after Treatment)      IR CornTREATMENT    g/ha  27 62 27 62 27                            62 27 62 27 62                                          27__________________________________________________________________________Imazethapyr + Imazapyr        12 + 4              63 100                    30 50 0 0  30 100                                     57 50                                          0        24 + 8              92 100                    78 70 37                            0  65 100                                     83 60                                          0        48 + 16              100                 100                    97 88 82                            50 87 100                                     97 75                                          13        60 + 20              100                 100                    88 85 37                            70 100                                  100                                     93 90                                          2        96 + 32              99 100                    100                       98 93                            95 99 100                                     100                                        95                                          22R-Imazethapyr + R-Imazapyr          8 + 2.7              77 100                    53 60 0 0  68 100                                     57 50                                          7         16 + 5.3              85 100                    88 50 37                            0  88 100                                     88 80                                          15        24 + 8              98 100                    97 95 63                            50 99 100                                     99 95                                          8          32 + 10.7              100                 100                    99 100                          90                            90 99 100                                     98 95                                          13          64 + 21.3              100                 100                    100                       100                          91                            98 100                                  100                                     100                                        98                                          13__________________________________________________________________________ 
    
     EXAMPLE 5 
     Field Evaluation of the Enhanced Herbicidal Effect of the Combination of the R-Isomers of Imazethapyr and Imazapyr 
     Using essentially the same procedure described in Example 4 and varying the location of the trial, a field evaluation of the combination of R-imazethapyr plus R-imazapyr is performed. Visual weed control evaluations are recorded at 36 and 69 days after treatment. Visual evaluation of % stunting of the IR corn crop is recorded at 36 days after treatment. The data obtained are shown in Table V. 
     
         ______________________________________PLANT SPECIESBayerCode    Scientific Name   Common Name______________________________________DIGSA   Digitaria sanguinalis, (L.)Scop.                     CrabgrassSORHAP  Sorghum halepense (L.) Pers.                     Johnsongrass, rhizome______________________________________ 
    
     
                       TABLE V______________________________________         % Weed Control                       %         DIGSA   SORHAP    Stunting  Rate     (Days After Treatment)                           IR CornCompound g/ha       36     69   36   69   36______________________________________Imazethapyr    12 + 4     60     53   0    40   0plus     24 + 8     93     77   --   68   0Imazapyr 48 + 16    92     87   65   70   10    60 + 20    99     92   93   70   3    96 + 32    98     95   93   88   3R-Imazethapyr      8 + 2.7  68     47   83   83   0plus       16 + 5.35               92     77   80   83   0R-Imazapyr    24 + 8     68     91   90   78   7      32 + 10.7               99     99   95   95   7      64 + 21.3               100    100  100  100  2______________________________________ 
    
     EXAMPLE 6 
     Postemergence Evaluation of the Enhanced Herbicidal Effect of the Combination of the R-Isomers of Imidazolinone Compounds 
     In this evaluation, plants are grown in standard greenhouse soil for 10-14 days until they are at the 2- to 4-leaf stage. Said plants are then sprayed with aqueous test solutions prepared from formulated technical material containing 0.25% of a non-ionic surfactant. Each treatment is replicated 3 to 4 times. After spraying, the plants are placed on greenhouse benches and cared for in a manner commensurate with conventional greenhouse practice. Approximately 3 weeks after treatment the plants are visually evaluated for % weed control as compared to the untreated check. The data are averaged and shown in Table VI. 
     
         ______________________________________PLANT SPECIESBayerCode   Scientific Name     Common Name______________________________________AMBEL  Ambrosia artemisiifolia, L.                      Ragweed, commonPANMI  Panicum miliaceum, L.                      Millet, wild prosoCYPRO  Cyperus rotundus, L.                      Nutsedge, purpleIPOHE  Ipomoea hederacea, (L)Jacq.                      Morningglory, ivyleafABUTH  Autilon theophrasti, Medic.                      VelvetleafDIGSA  Digitaria sanguinalis, (L)Scop                      CrabgrassECHCG  Echinochloa Crus-Galli, (L) Beau                      BarnyardgrassCHEAL  Chenopodium album, L.                      LambsquartersCASOB  Senna obtusifolia, (L.)                      Sicklepod______________________________________ 
    
     
                                           TABLE VI__________________________________________________________________________Postemergence Herbicidal Evaluation__________________________________________________________________________        RATE   % WEED CONTROLTREATMENT    g/ha   AMBEL                    PANMI                        CYPRO                            IPOHE                                ABUTH                                     DIGSA                                         CASOB__________________________________________________________________________Imazaquin + Imazapyr        1.5 + 0.5               3    0   3   3   3    8   --        3 + 1  8    8   0   9   5    8   --        6 + 2  24   20  3   19  18   10  --        12 + 4 45   13  5   33  43   23  --         8 + 24               76   40  30  50  80   63  --        16 + 48               84   69  45  80  95   94  --        32 + 96               95   95  64  89  100  100 --R-Imazaquin + R-Imazapyr        1.5 + 0.5               13   6   0   0   6    5   --        3 + 1  15   30  3   4   10   15  --        6 + 2  38   13  10  36  29   18  --        12 + 4 69   33  34  53  53   48  --         8 + 24               85   78  48  79  96   88  --        16 + 48               90   95  50  88  100  100 --        32 + 96               99   100 65  93  100  100 --Imazamox + Imazapyr        0.75 + 0.25               5    0   5   0   0    0   --        1.5 + 0.5               14   6   0   3   16   0   --        3 + 1  31   46  24  21  29   11  --        6 + 2  58   28  20  29  54   31  --        12 + 4 68   66  23  50  85   68  --        24 + 8 78   83  45  71  100  93  --        48 + 16               96   97  74  84  96   99  --R-Imazamox + R-Imazapyr        0.75 + 0.25               11   23  3   6   5    5   --        1.5 + 0.5               16   31  5   10  14   6   --        3 + 1  28   14  14  16  35   15  --        6 + 2  53   54  10  45  59   19  --        12 + 4 78   65  30  60  91   73  --        24 + 8 90   93  50  81  100  94  --        48 + 16               97   98  73  91  100  100 --Imazapic + Imazapyr         0.25 + 0.125               0    0   0   0   --   --  0         0.5 + 0.25               0    1   1   0   --   --  0          1 + 0.5               0    5   3   5   --   --  3        2 + 1  11   48  5   20  --   --  6        4 + 2  21   91  8   79  --   --  15        8 + 4  73   100 20  81  --   --  49        16 + 8 88   100 64  95  --   --  74R-Imazapic + R-Imazapyr         0.25 + 0.125               0    0   0   0   --   --  0         0.5 + 0.25               0    0   0   0   --   --  0          1 + 0.5               5    46  3   33  --   --  3        2 + 1  21   71  21  68  --   --  8        4 + 2  48   100 5   73  --   --  54        8 + 4  88   100 25  90  --   --  74        16 + 8 86   100 61  94  --   --  83Imazethapyr + Imazapic        0.75 + 0.25               0    0   0   0   0    0   --        1.5 + 0.5               15   5   0   5   3    13  --        3 + 1  19   18  5   19  13   14  --        6 + 2  40   28  28  28  18   35  --        12 + 4 60   46  30  38  55   68  --        24 + 8 66   58  45  65  86   91  --        48 + 16               90   93  75  80  98   98  --R-Imazethapyr + R-Imazapic        0.75 + 0.25               10   0   10  0   3    5   --        1.5 + 0.5               10   20  5   3   5    5   --        3 + 1  20   8   5   13  18   16  --        6 + 2  50   38  21  25  64   43  --        12 + 4 53   80  28  53  73   65  --        24 + 8 86   80  45  75  88   93  --        48 + 16               91   98  89  96  89   99  --Imazaquin + Imazethapyr        4 + 2  10   1   1   16  --   --  0        8 + 4  34   20  14  15  --   --  1        16 + 8 71   73  15  71  --   --  1        32 + 16               81   90  53  75  --   --  29        64 + 32               86   93  50  80  --   --  65R-Imazaquin + R-Imazethapyr        4 + 2  24   26  6   8   --   --  3        8 + 4  51   55  38  53  --   --  8        16 + 8 69   58  16  70  --   --  8        32 + 16               88   88  65  76  --   --  43        64 + 32               95   96  71  83  --   --  75Imazaquin + Imazamox        6 + 2  11   0   4   6   10   0   --        12 + 4 24   3   8   10  21   6   --        24 + 8 35   15  9   18  30   38  --        48 + 16               71   45  23  39  71   84  --        96 + 32               78   66  29  60  89   98  --R-Imazaquin + R-Imazamox        6 + 2  13   3   9   8   14   6   --        12 + 4 26   5   9   9   18   20  --        24 + 8 64   19  18  24  33   50  --        48 + 16               76   54  29  48  76   89  --        96 + 32               85   79  65  65  80   94  --__________________________________________________________________________               % WEED CONTROL        RATE        AM- A-TREATMENT    g/ha   CHEAL                    BEL BUTH                            CASOB                                ECHCG                                     IPOHE__________________________________________________________________________Imazethapyr + Imazamox         0.5 + 0.25               5    3   14  0   19   5          1 + 0.5               28   9   19  0   58   36        2 + 1  23   41  50  0   64   43        4 + 2  39   63  63  3   71   63        8 + 4  58   75  80  4   85   76        16 + 8 65   76  80  30  99   73        32 + 16               77   83  98  53  99   79R-Imazethapyr + R-Imazamox         0.5 + 0.25               3    6   14  3   15   1          1 + 0.5               31   41  18  0   59   40        2 + 1  33   56  56  3   69   46        4 + 2  48   71  70  4   79   66        8 + 4  64   75  80  11  94   78        16 + 8 61   75  79  34  100  75        32 + 16               82   85  98  61  97   83__________________________________________________________________________ 
    
     EXAMPLE 7 
     Preemergence Evaluation of the Enhanced Herbicidal Effect of the Combination of the R-Isomers of Imidazolinone Compounds 
     In this evaluation, plant seeds are sown in pots containing a Sassafras sandy loam soil. Test solutions prepared as described in Example 6 are applied to the soil by spray application. After spraying, the plants are placed on greenhouse benches and cared for in a manner commensurate with convention al greenhouse practice. Each treatment was replicated 3-4, times. Approximately 3 weeks after treatment, visual evaluations of % weed control as compared to the untreated check are recorded. The data are averaged and shown in Table VII. 
     
         ______________________________________PLANT SPECIESBayerCode    Scientific Name   Common Name______________________________________CYPRO   Cyperus rotundus, L.                     Nutsedge, purplePANMI   Panicum miliaceum, L.                     Millet, wild prosoAMBEL   Ambrosia artemisiifolia, L.                     Ragweed, commonDIGSA   Digitaria sanguinalis, (L)Scop                     CrabgrassABUTH   Abutilon theophrasti, Medic.                     VelvetleafIPOHE   Ipomoea hederacea, (L)Jacq.                     Morningglory, ivyleafCASOB   Senna obtusifolia, L. Irwin and                     Sicklepod   Barneby______________________________________ 
    
     
                                           TABLE VII__________________________________________________________________________Preemergence Herbicidal Evaluation        RATE  % WEED CONTROLTREATMENT    g/ha  CYPRO                  PANMI                      AMBEL                           DIGSA                               ABUTH                                    IPOHE                                        CASOB__________________________________________________________________________Imazamox + Imazapyr        0.75 + 0.25              1   3   1    5   21   1   --        1.5 + 0.5              3   4   4    4   61   28  --        3 + 1 6   9   5    23  83   46  --        6 + 2 40  38  33   31  63   56  --        12 + 4              44  59  60   45  99   75  --        24 + 8              81  75  71   69  95   79  --        48 + 16              94  89  79   93  95   84  --R-Imazamox + R-Imazapyr        0.75 + 0.25              3   5   4    3   19   3   --        1.5 + 0.5              5   1   6    6   23   8   --        3 + 1 5   4   3    10  48   20  --        6 + 2 21  39  18   45  85   64  --        12 + 4              61  73  59   55  98   79  --        24 + 8              81  76  68   79  100  81  --        48 + 16              84  86  75   91  96   84  --Imazapic + Imazapyr          1 + 0.5              0   26  3    --  --   50  0        2 + 1 3   61  41   --  --   77  28        4 + 2 54  73  45   --  --   81  35        8 + 4 70  79  74   --  --   84  73        16 + 8              83  81  82   --  --   91  93        32 + 16              97  90  91   --  --   90  93R-Imazapic + R-Imazapyr          1 + 0.5              0   31  11   --  --   52  0        2 + 1 31  69  63   --  --   75  38        4 + 2 66  78  68   --  --   84  65        8 + 4 75  87  75   --  --   88  51        16 + 8              96  92  93   --  --   90  98        32 + 16              100 95  94   --  --   92  94Imazaquin + Imazapyr        1.5 + 0.5              0   1   4    1   16   3   --        3 + 1 5   9   9    15  38   18  --        6 + 2 29  15  11   16  49   41  --        12 + 4              40  21  46   48  73   54  --        24 + 8              78  36  68   48  88   73  --        48 + 16              74  63  75   71  99   81  --        96 + 32              100 76  84   84  99   83  --R-Imazaquin + R-Imazapyr        1.5 + 0.5              4   3   9    4   21   4   --        3 + 1 10  0   11   11  35   1   --        6 + 2 13  6   25   9   59   40  --        12 + 4              29  30  65   43  78   69  --        24 + 8              64  50  76   66  89   74  --        48 + 16              84  69  75   71  89   80  --        96 + 32              90  74  81   94  99   81  --Imazaquin + Imazapic        2.25 + 0.5              3   3   6    --  --   8   10        4.5 + 1              4   16  9    --  --   44  3        9 + 2 34  58  59   --  --   76  14        18 + 4              65  80  78   --  --   76  14        36 + 8              71  96  91   --  --   94  80R-Imazaquin + R-Imazapic        2.25 + 0.5              1   13  28   --  --   38  13        4.5 + 1              11  45  48   --  --   70  25        9 + 2 48  66  79   --  --   85  33        18 + 4              83  87  89   --  --   91  70        36 + 8              99  97  96   --  --   93  91Imazaquin + Imazamox        3 + 1 0   3   0    3   0    3   --        6 + 2 0   3   16   5   48   16  --        12 + 4              0   6   46   45  59   50  --        24 + 8              5   29  84   63  81   73  --        48 + 16              28  61  91   71  94   85  --        96 + 32              68  90  97   90  98   97  --R-Imazaquin + R-Imazamox        3 + 1 0   3   14   4   40   10  --        6 + 2 1   3   58   33  53   24  --        12 + 4              6   53  65   53  73   71  --        24 + 8              11  63  75   73  84   78  --        48 + 16              59  78  92   84  95   94  --        96 + 32              80  99  98   98  98   93  --Imazaquin + Imazethapyr        4 + 2 0   6   9    16  33   0   --        8 + 4 8   13  25   30  64   45  --        16 + 8              46  59  74   60  80   78  --        32 + 16              68  68  86   71  83   80  --        64 + 32              84  81  93   86  93   91  --R-Imazaquin + R-Imazethapyr        4 + 2 4   20  31   20  59   0   --        8 + 4 28  51  71   60  68   0   --        16 + 8              75  64  83   73  83   78  --        32 + 16              86  84  95   80  93   91  --        64 + 32              97  89  95   97  97   94  --Imazethapyr + Imazamox        2 + 1 0   5   0    8   45   6   --        4 + 2 14  34  8    20  63   44  --        8 + 4 35  53  25   58  84   71  --        16 + 8              63  76  70   74  94   89  --        32 + 16              85  85  84   90  97   94  --R-Imazethapyr + R-Imazamox        2 + 1 4   14  3    14  58   11  --        4 + 2 18  25  23   40  71   35  --        8 + 4 43  49  55   51  84   69  --        16 + 8              80  76  79   76  93   88  --        32 + 16              91  90  88   92  97   94  --__________________________________________________________________________ 
    
     EXAMPLE 8 
     Evaluation of the Enhanced Herbicidal Effect of the Combination of the R-Isomers of Imidazolinone Compounds in Imidazolinone Tolerant (IT) Corn 
     Field trials are conducted at various locations across the United States. The experimental design of each trial is a modified randomized complete block with a minimum 3 replications per treatment. Plot size is 10 to 12 feet wide and 30 to 40 feet long. 
     Planting time of IT corn varies depending on weather conditions and geographic region but is generally in late April to mid-June. Site preparation is consistent with local cultural practices and generally consists of 1 to 2 passes with a disc or field cultivator. IT Corn is sown in 30 inch rows. 
     Herbicides are applied with a tractor mounted sprayer equipped with a 10 to 12 foot boom, 8002 or 8003 flat fan nozzle tips, and delivering 20 gallons per acre (gpa) diluent volume pressurized at 35 to 45 psi. Postemergence herbicide application timings are based on weed and crop growth, and are generally at 1 to 3 inch weeds, or 5 to 8 inch corn. 
     Weed control in IT Corn trials is visually evaluated approximately 28 DAT (Table VIII)and 56 DAT (Table IX) and expressed as percent weed control (0 to 100% basis). 
     The data is averaged and shown in Tables VIII and Table IX. 
     
                                           TABLE VIII__________________________________________________________________________ Rate   giant   pitted                    ivyleaf                        fall broadleaf                                  purple                                       Texas                                            vevlet lbs/A  ragweed            Eclipta                mgg mgg panicum                             signalgr                                  nutsedge                                       panicum                                            leaf__________________________________________________________________________imazapic/    0.021 + .0042        69  75   80  95  97   90   67  72    99imazapyrR-imazapic/ .014 + .003            776 92  98  99   90   65   70   99R-imazapyrimazapic/    .032 + .0064        88  93  93  97  99   85   68   73   99imazapyrR-imazapic/  .021 + .0042        76  97  87  100 98   86   50   53   99R-imazapyrimazapic/    .047 + .0094        89  97  96  97  100  95   75   80   99imazapyrR-imazapic/  .032 + .0064        87  95  95  98  100  93   73   75   99R-imazapyrimazapic/   .094 + .019            966 97  97  100  96   80   80   99imazapyrR-imazapic/ .064 + .013            986 97  96  100  96   80   83   99R-imazapyrimazapic 0.047  82  89  91  96  100  89   73   77   99R-imazapic 0.032  84  90  89  96  99   80   60   62   99__________________________________________________________________________ Rate   woolly             sickle                Johnson                    redroot                        carpet                            cult.d                                 giant                                     common                                           common lbs/A  cupgrass             pod                grass                    pigweed                        weed                            sunflower                                 foxtail                                     waterhemp                                           cocklebur__________________________________________________________________________imazapic/      0.021 + .0042         96  55 93  53  53  100  95  85    90imazapyrR-imazapic/   .014 + .003            94             81 90  82  80   95  99  88    96R-imazapyrimazapic/      .032 + .0064           93             82 82  85  85  100  99  87    93imazapyrR-imazapic/    .021 + .0042           96             79 87  85  83   90  99  95    98R-imazapyrimazapic/      .047 + .0094           97             91 97  83  83  100  99  93    97imazapyrR-imazapic/    .032 + .0064           99             86 98  80  80  100  99  90    93R-imazapyrimazapic/     .094 + .019             9699                97  92  92  100  99  93    93imazapyrR-imazapic/   .064 + .013             9699                95  95  95  100  100 80    93R-imazapyrimazapic      0.047             81 93  80  82  1007 98  87    95R-imazapic    0.032             80 82  83  87  1007 99  83    90__________________________________________________________________________ 
    
     
                                           TABLE IX__________________________________________________________________________     Rate  water              fall green                       Palmer                           redroot                               cockle                                   comm                                       barnyard                                            hairy                                                giant                                                   shatter                                                       giant     lbs/A hemp              panicum                   foxtail                       amar                           pigweed                               bur lambs                                       grass                                            nightsh                                                foxt                                                   cane                                                       rag__________________________________________________________________________imazethapyr/imazapyr     .021 + .007           39 50   72  86  93  79  96  93   98  49 55  82R-imazethapyr/     .014 + .005           55 82   93  93  97  79  93  92   98  55 95  78R-imazapyrimazethapyr/imazapyr     .042 + .014           43 78   96  95  98  85  96  94   98  74 100 40R-imazethapyr/     .028 + .009           58 99   99  95  98  91  95  97   97  76 100 37R-imazapyrimazethapyr/imazapyr     .084 + .028           47 99   100 95  97  83  98  97   100 88 100 77R-imazethapyr/     .056 + .018           69 100  100 93  97  93  98  98   100 91 100 74R-imazapyr__________________________________________________________________________