METHOD OF CONTROLLING WEEDS IN TRANSGENIC CROPS

Abstract: The invention relates to a method for the control of weeds at a crop locus, said method comprising the application of an effective amount of: (a) a glyphosate herbicide which is glyphosate or a derivative thereof; and (b) at least one HPPD-inhibiting herbicide; wherein the crop is tolerant to glyphosate and optionally the HPPD-inhibiting herbicide.

Description: Method of controlling weeds in transgenic crops Background of the Invention This invention relates to compositions comprising of a 5- enol pyruvyl shikimate-3-phosphonate synthase-inhibiting herbicide (such as glyphosate) and ap-hydroxyphenylpyruvate dioxygenase-inhibiting herbicide, and to their use on transgenic crops, in particular com (Zea mays) and soybean. Discussion of Related Art Inhibitors of the enzyme p-hydroxyphenylpyruvate dioxygenase (HPPD) are discussed in a number of papers (Prisbykka et al, Proc. Brighton Crop Prot. Vol. 2, (1993), pp731 - 738; Schulz et al., FEBS Utters, No. 2 (1993), Vol. 2, 162-166; Pallett et al, Pestic. Sci., Vol. 50 (1997) pages 83-84; and Lee et al. Weed Science Vol.45 ( 1997) pages 601 - 609). HPPD-inhibiting herbicides are known in the literature, for example pyrazolate-type herbicides; 4-benzoylisoxazole herbicides (e.g. 5-cyclopropyl-4-(2-methylsulfonyl-4-trifluoromethylbenzoyl)isoxazole, known by the common name isoxaflutole), and 2-benzoylcyclohexane- 1,3-dione herbicides [e.g.2-(2-chloro-4-methylsulfonylbenzoyl)- cyclohexane-l,3-dione, known by the common name sulcotrione; and 2- (2'-nitro-4'-methylsulfonylbenzoyl)cyclohexane-l,3-dione]. These compounds possess good levels of weed control. However, under certain conditions, (e.g. where high levels of weed infestation exist and it is desirable to use higher dose rates of the compounds; or where the compounds are to be applied post-emergence) there can be a problem with the selectivity of these compounds in the presence of crops, for example soybeans or maize. Herbicides inhibiting 5-enol pynιvyishikimate-3-phosphonate synthase (EPSPS) are well known as highly effective foliar herbicides. The most well known herbicide of this class of herbicide is glyphosate [N-(phosp oπomethyI)glycine]. Glyphosate lacks selectivity in crop species and has therefore been used under conditions where there is no need for selectivity (e.g. as a total herbicide) or under conditions where there is no growing crop foliage present (e.g. burn-down/no-till). An alternative approach to the above limitations is to use the above compounds in the presence of crops which have been genetically modified to provide enhanced tolerance to the compounds. For example US Patent Nos.4,535,060; 4,769,061; 5,633,435; 5,627,061; 4,940,835; relate to the modification of crops to confer tolerance to EPS PS-inhibitin (e.g. glyphosate) herbicides. WO96/38567 describes transgenic crops having enhanced tolerance to HPPD-inhibiting compounds. inhibitors The increased use of EPSPS/tolerant plants, for example in the Round-up Ready™ com and soybean seeds now available has allowed farmers to apply glyphosate in areas where the crop is growing, without causing unacceptable levels of damage to the crop. The combination of isoxaflutole and glyphosate is known for the use in burn-down/no-till control. However, this is applied in an area where the crop has not emerged and thus selectivity is not a necessary requirement, and further treatments of the field may be needed by the farmer using selective herbicides after sowing the seed to remove weeds which emerge after the application of the herbicide. This requires additional time and expense on the part of the farmer. An object of the invention is to provide a single treatment to control weeds present at a crop locus. A further object of the invention is to provide a method which maximises crop yield. A still further object of the invention is to provide a method which allows the farmer to avoid applying unnecessary treatments of herbicide before the emergence of weeds, which allows the farmer maximum flexibility in deciding on a treatment programme. These and other objects will become apparent from the following description, which are achieved in whole or in part by the present invention. Summary of the Invention The present invention provides a method for the control of weeds at a crop locus, said method comprising the application of an effective amount of: (a) a glyphosate herbicide which is glyphosate or a derivative thereof; and (b) at least one HPPD-inhibiting herbicide; wherein the crop locus comprises a crop tolerant to said glyphosate herbicide. Description of Preferred Embodiments Preferably the transgenic crop is tolerant to glyphosate and said least one HPPD-inhibiting herbicide at the doses used. Generally the herbicides are applied post-emergence of the crop, preferably early-post emergence. By the term "early post emergence" is meant the first four weeks after emergence of the crop. The application of the combination of the invention is preferably made two weeks after emergence of the crop. This period is very important in influencing the final yield potential of the crop. Typically, during the early post- emergent period when the crop is maize, the crop height is less than about 15 cm (preferably less than about 10 cm) and the weed height is less than about 10 cm (preferably less than about 5 cm). The application of (a) and (b) is preferably made early post- emergence as this allows the control of late-germinating weeds to be accomplished without the need to apply a second application of the glyphosate herbicide which, while effective in controlling weeds which have emerged at the time of their application, generally do not control weeds which have protracted germinating periods (due to the lack of residual activity in these compounds) and thus need to be applied again late-post emergence. The HPPD-inhibiting herbicide provides a residual activity. Furthermore, the use of an HPPD-inhibiting herbicide in combination with glyphosate also lessens the risk of weed population shifts, due to increasing application of a single herbicide over successive seasons. Weeds that may be controlled by the method of the invention include grass weeds, broad-leaf weeds and sedges. The method of the invention is particularly useful in controlling certain weeds which glyphosate may not fully control, in particular waterhemp (Amaranthus spp ) . nightshades and velvetleaf (Abutiloπ theophrasti). Examples of grass weeds include Alopecurus mvosuroides. Avena fatua. Digitaria sanguinalis. Echinochloa crus-galli. Sorghum bicolor, Eleusine indica and Setaria spp. e.g. Setaria faberii or Setaria viridis. Examples of broad-leaf weeds include Abutilon theophrasti. Amaranthus retroflexus. Bidens pilosa. Chenopodium album. Galium aparine. Ipomoea spp. e.g. Ipomoea purpurea. Sesbania exaltata. Sinapis arvensis. Solanum nigrum and Xanthium strumarium. An example of a sedge includes Cvperus esculentus. The crop species which may be used in the method of the invention include maize, sugarcane, soybean, cotton, canola, clover, sugar beet, grain sorghum, peas, beans, potatoes, peanuts.wheat and barley. Preferred crops include maize, sugarcane, soybean, cotton, canola and clover. Particularly preferred crop species are maize and soybean, especially maize. Preferably the crop contains a gene which encodes class II EPSPS enzyme. Crops possessing enhanced tolerance to both glyphosate herbicides and HPPD-inhibiting herbicides are described in PCT application No. PCT/FR97/01256, which was filed before the present application but was unpublished at the date of filing. 86 - 5 - In general the application rate of the glyphosate herbicide is from about 400 to about 1200 g acid equivalent (a.e.)/ha, preferably from about 500g ha to about 800 g a.e. ha; and the application rate of the HPPD-inhibiting herbicide is generally from about 20g/ha to about 500g/ha, preferably from about 40g/ha to about 150g ha. It will be understood that the application rates used will depend on the growth stage of the weeds, the climatic conditions, the time of application, the type of weeds present, the crops and other parameters apparent to the skilled worker. The glyphosate herbicide may be applied in its acid form or as a derivative thereof, such as the mono isopropylammonium salt, the sodium salt, trimesium salt (sulfosate) or a mixture thereof. Preferably the mono isopropylammonium salt is used. Preferably the weight ratio of (a):(b) is from about 0.8:1 to about 60:1, more preferably from about 3.3:1 to about 20:1. In one prefe ed aspect of the present invention the HPPD-inhibiting herbicide is a 4-benzoylisoxazole herbicide, preferably having the general formula(I): (D wherein R is hydrogen or -CO2R^; R 1 is Cι_4 alkyl or C3.6 cycloalkyl optionally substituted by Cj_6 alkyl; R2 is selected from halogen, nitro, cyano, -S(O)pR6, -(CR R5) q S(O) p R 6 , -N(R 7 )SO 2 R 6 , C]. 6 alkoxy, -OSO 2 R 6 , C haloalkoxy, C]_4 alkyl and Cj^ haloalkyl; or two groups R-, on adjacent carbon atoms of the phenyl ring may, together with the carbon atoms to which they are attached, form a 5 - 6 - or 6 membered saturated or unsaturated heterocychc πng containing up to three πng heteroatoms selected from nitrogen, oxygen and sulfur, which πng may be optionally substituted by one or more groups selected from halogen, nitro, -S(O) p R 6 , C}_4 alkyl, Cι_4 alkoxy, Cj_4 haloalkyl and C \ _4 haloalkoxy , it being understood that a sulphur atom, where present in the ring, may be in the form of a group -SO- or -SO2-; n is an integer from one to five; p is zero, one or two; q is one or two; where q is two the groups (CR 4 R5) may be the same or different; R3 is C alkyl; R and R5 are independently hydrogen or Cj_4 alkyl; ^ IS CI_4 alkyl, or phenyl or benzyl, each of phenyl and benzyl optionally bearing from one to five substituents which may be the same or different selected from the group consisting of halogen, Cj .4 alkyl, Cj_4 alkoxy, C1.4 haloalkyl, Cι_4 haloalkoxy, nitro and -S(O)pCH3; and R 7 is hydrogen or Cj.ζ alkyl; or an agriculturally acceptable salt thereof. In this descπption the term "agriculturally acceptable salts" means salts the cations or anions of which are known and accepted in the art for the formation of salts for agπcultural or horticultural use. Preferably the salts are water-soluble. Suitable salts with bases include alkali metal (eg. sodium and potassium), alkaline earth metal (eg. calcium and magnesium), ammonium and amine (eg. diethanolamine, triethanolamine, octylamine, morpholine and dioctylmethylamine) salts. Suitable acid addition salts, formed by compounds of formula (I) containing an nitrogen atom with an available lone pair, include salts with inorganic acids, for example hydrochloπdes, sulphates, phosphates and nitrates and salts with organic acids, for example acetic acid. It will be understood that in certain cases the groups R' , R2, R3, R 4 , R$, R6 and R 7 may give rise to siereoisomers and geometric isomers All such forms are embraced by the present invention Throughout this description the terms "alkyl" and "alkoxy" refer to 6 - 7 - straight or branched chains. The terms "haloalkyl" and "haloalkoxy" refer to alkyl and alkoxy respectively, each substituted by at least one halogen. The term "halogen" refers to fluorine, chlorine, bromine and iodine. In formula (I) above, preferably R is hydrogen or -CO2CH2CH3. In formula (I) above, preferably n is two or three. R* is preferably cyclopropyl. Compounds of formula (I) in which either n is three and the groups (R2) n occupy the 2,3 and 4-positions of the benzoyl ring; or in which n is two and the groups (R 2 ) n occupy the 2 and 4- positions of the benzoyl ring; are preferred. In formula (I) above, R 2 is preferably selected from halogen (preferably chlorine or bromine), -S(O)pMe, trifluoromethyl, C j .4 haloalkoxy, Cj^ alkoxy and -CH2S(O)pMe. In formula (I) above, preferably one of the groups R^ is -S(O)pMe. Compounds of formula (I) of particular interest include 5-cyclopropyl-4-(2-methylsulphonyl-4- trifluoromethyl)benzoylisoxazole; 4-(2-chloro-4- methylsulphonyl)benzoyl-5-cyclopropylisoxazole; 4-(4-chloro-2- methylsulphonyl)benzoyl-5-cyclopropylisoxazole; 4-(4-bromo-2- methylsulphonyl)benzoyl-5-cyclopropylisoxazole; ethyl 5-cyclopropyl- 4-(2-methylsulphonyl-4-trifluoromethyl)benzoylisoxazole-3- carboxylate; 4-[4-bromo-2-(methylsulphonylmethyl)benzoyl]-5- cyclopropylisoxazole; 4-[4-bromo-3-(2,2-difluoroethoxy)-2- methylsulphonylbenzoyl]-5-cyclopropylisoxazole; 5-cyclopropyl-4-[2,2- difluoro-4-(methanesulphonylmethyl)- 1 ,3-benzodioxoI-5-oyl]isoxazole and 5-cyclopropyl-4-(4-fluoro-3-methoxy-2- methylsulphonylbenzoy isoxazole. Most preferably the compound of formula (I) is 5-cyclopropyl-4-(2-methylsulphonyl-4- trifluoromethyl)benzoylisoxazole or 5-cyclopropyl-4-(4-fluoro-3- methoxy-2-methylsulphoπylbenzoyl)isoxazole. 6 - 8 - Herbicidal 4-benzoylisoxazoies are known from EP418175, EP487357, EP527036, EP560482, WO94/14782, and United States Patent Nos. 5,371,064; 5,371,063; 5,489,570 and 5,656,573. Where the HPPD -inhibiting herbicide is a 4-benzoylisoxazole, it is generally applied at an application rate from about 20g ha to about 500g/ha, preferably from about 40g/ha to about 150g/ha, more preferably from about 60g ha to about 80g ha. It has unexpectedly been found that in certain cases where the HPPD-inhibiting herbicide is a 4-benzoyIisoxazole the combinations of the present invention provide a synergistic level of control of one or more weed species and in a further preferred feature of the present invention there is provided a synergistic herbicidal composition comprising a compound of formula (I) above and a glyphosate herbicide which is glyphosate or a derivative thereof, in association with a agriculturally acceptable diluent or carrier. Preferably the compound of formula (I) is 5-cyclopropyl-4-(4-fluoro-3-methoxy-2- methylsulphonylbenzoyl)isoxazole. In another preferred aspect of the present invention me HPPD-inhibiting herbicide is a 2-benzoyl-cyclohexane-l,3-dione derivative, preferably having the general formula (IT): (H) wherein R^ is hydrogen, C\. alkyl, or phenyl; X is oxygen or -S(O) z where z is zero, one or two; R 12 , R 13 , R 14 , R 15 , R 16 and R 17 independently represent hydrogen or C\. alkyl: or Rl2 and R^ 4 , together with the carbon atoms to which they are attached, form a three to five membered saturated carbocyclic ring; or R 1 and R 1 together form an ethylene radical; R 8 is nitro, halogen, cyano. Cj_4 alkyl, C j _4 haloalkyl, C j _ alkoxy, Cj^ haloalkoxy or -S(O) z R 20 ; Rl9 js halogen, nitro, cyano, C j ^ alkyl, C j _4 alkoxy, Cι _4 haloalkyl, Cμ haloalkoxy, -NR 21 R 22 , -S(O) 2 R 2 3, -OSO 2 R 23 , -(CR2 R25 )a s(0) z R 3 or -NR 2 6S0 2 R 23 , e is an integer from one to four; R20 represents C 1.4 alky 1 ; R21 ( 22 t R24 ( R25 ^^ R26 independently represent hydrogen or C ι_4 alkyl; R 23 is C1. alkyl, phenyl or benzyl, each of phenyl and benzyl optionally bearing from one to five substituents which may be the same or different selected from the group consisting of halogen, C \ , alkyl, C j _4 alkoxy, C 1.4 haloalkyl, Cj _4 haloalkoxy, nitro and -S(O) z CH3; a is one or two. where a is two the groups (CR 4 R 2 ^) may be the same or different: an enoiic tautomeric form thereof, or an agriculturally acceptable salt or metal complex thereof. It will be understood that the compounds of formula (II) may exist in eπolic tautomeric forms that may give rise to geometric isomers. Furthermore, in certain cases the groups R to R* may give rise to stereoisomers and geometric isomers. All such forms are embraced by the present invention. In this description by the term "metal complexes" is meant compounds in which one or both of the oxygen atoms forming part of a 1 ,3-dione [in formula (II) and (III)] act as chelating agents to a metal cation. Examples of such cations include zinc, manganese, cupric, cuprous, ferric, ferrous, titanium and aluminium. It will be understood that in the description that follows, reference to compounds of formula (II) or (IH) includes agriculturally acceptable salts, metal complexes or enoiic tautomeric forms thereof. Preferably the compounds of formula (LI) may be provided in the form of a metal complex, in particular a transition metal complex, for example as described in International Patent Application No. WO97/277848. Preferably R 1 is hydrogen and X is oxygen. Preferably R 2 , R 13 , R J 6 and R 17 each represent hydrogen, and R 14 and R 15 independendy represent hydrogen or methyl. Preferably R^ is halogen or nitro. Preferably R 19 is Cμ alkoxy or -S(O) z R 23 or -OSO2R 23 , where R 23 is C j _4 alkyl. More preferably R 9 is ethoxy or -S(O) z R 23 , where R 23 is methyl or ethyl. Most preferably a group R 19 is -SO2CH3 and occupies the 4-position of the benzoyl ring. e is preferably one or two. When e is one preferably R ' 9 occupies the 4-position of the benzoyl ring; when e is two preferably the two groups RI 9 occupy the 3- and 4- positions of the benzoyl ring. Preferably the compound of formula (II) is 2-(2-chloro-4- methylsulfonylbenzoyDcyclohexane- ! .3-dione (sulcotrione): 2-(2'-nitro- 4'-methylsulfonylbenzoyl)cyclohexane-l,3-dioπe: 2-(2'-πitro-4'- 6 methylsulfonyioxybenzoyl)cyclohexane-l,3-dione; or 2-(2'-chloro- 3-ethoxy-4'-ethylsulfonylbenzoyl)-4-methylcyclohexane-l,3-dione, or an agriculturally acceptable salt or metal complex thereof. Compounds of formula (II) are known from US5006158; US4780127, US4806146, US4946981, WO9408988 and WO9404524, the contents of which are incorporated herein by reference and relied upon. 86 - 12 - In yet another preferred aspect of the invention the HPPD- inhibiting herbicide is 2-cyano-1.3-dione herbicide, preferably having the general formula (HI): (DD wherein R 3 ^ is Cj_4 alkyl or C3.6 cycloalkyl optionally substituted by C\. alkyl; R 31 is selected from halogen, nitro, cyano, -S(O) r R 32 , -(CR 3 R 3 4) v S(O) r R 32 , -N(R 3 5)SO 2 R 32 , C . 6 alkoxy, -OSO 2 R 32 , Cι_4 haloalkoxy, C\^ alkyl and Cj^ haloalkyl; or two groups R 3 on adjacent carbon atoms of the phenyl ring may, together with the carbon atoms to which they are attached, form a 5 or 6 membered saturated or unsaturated heterocyclic ring containing up to three ring heteroatoms selected from nitrogen, oxygen and sulfur, which ring may be optionally substituted by one or more groups selected from halogen, nitro, -S(O) r R 32 , Cj_4 alkyl, C 1.4 alkoxy, Cι_4 haloalkyl and C ι_4 haloalkoxy, it being understood that a sulphur atom, where present in the ring, may be in the form of a group -SO- or -SO2-; t is an integer from one to five (preferably one, two or three); r is zero, one or two; R 32 is Cj_4 alkyl, or phenyl or benzyl, each of phenyl and benzyl optionally bearing from one to five substituents which may be the same or different selected from the group consisting of halogen, Cj_4 alkyl, Cι_4 alkoxy, Cj .4 haloalkyl, C]_4 haloalkoxy, nitro and -S(O) r CH3; R 33 , R 34 and R 35 are independently hydrogen or C 1.4 alkyl; v is one or two: where v is two the groups (CR 33 R 34 ) may be the same or different; an enoiic tautomeric form thereof, or an agriculturally acceptable salt or metal complex thereof. 6 - 13 - It will be understood that the compounds of formula (HI) may exist in enoiic tautomeric forms that may give rise to geometric isomers around the enoiic double bond. Furthermore, in certain cases the groups R ^ to R 32 may give rise to stereoisomers and geometric isomers. All such forms are embraced by the present invention. R 3 ^ is preferably 1-methylcycloproρyl or, most preferably cyclopropyl. In formula (IH) above, R 3 1 is preferably selected from halogen (preferably chlorine or bromine), -S(O) r Me, trifluoromethyl, Cι_4 haloalkoxy, Cj^.alkoxy and -CH2S(O) r Me. In formula (ID) above, preferably one of the groups R 3 1 is -S(O) r Me. Compounds of formula (III) of particular interest include 3-cyclopropyl-2-cyano-l-(2-methylsulphonyl-4- trifluoromethylphenyl)propan-l,3-dione; l-(2-chloro-4- methylsulphonylphenyl)-2-cyano-3-cyclopropylpropan- 1 ,3-dione; 2-cyano-3 -cyclopropyl- l-(4-fluoro-3-methoxy- 2-methylsulphonylphenyl)propan- 1 ,3-dione; 2-cyano- 1 - (4-methylsulphonyl-2-trifluoromethylpheπyl)-3- ( 1 -methylcyclopropyl)propan- 1 ,3-dione; and 1 -(4-chloro-2- methylsulphonylphenyl)-2-cyano-3-cyclopropylpropan- 1 ,3-dione. Compounds of formulamin which either t is three and the groups 31 ) t occupy the 2,3 and 4-positions of the benzoyl ring; or in which t is two and the groups (R t occupy the 2 and 4- positions of the benzoyl ring; are preferred. Compounds of formula (HI) are known from EP469630, EP469631 and EP560482, the contents of which are incorporated herein by reference and relied upon. The following non-limiting example illustrates the invention. Example 1 The following non-limiting example illustrates the invention. Example 1 The following experiment were conducted in Iowa and South Dakota with applications of 5-cyclopropyl-4-(4-fluoro-3-methoxy-2- methylsulphonylbenzoyl)isoxazole (hereafter referred to as the "isoxazole"; technical material formulated as a suspension concentrate containing 200g/l active ingredient) and the isoproylamine salt of glyphosate (using the commercial formulation "Roundup Bioforce", registered trade mark, a soluble concentrate containing 360g/l active ingredient plus adjuvants) alone or in tank mix combination. Roundup- Ready ' soybeans were used in the trials, which is a glyphosate tolerant crop; the varieties used in Iowa were Pioneer 921 1RR (P9211RR), Pioneer 9294RR (P9294RR); and the varieties used in S Dakota were DeKalb 266 (DEK266), DeKalb 296 (DEK296), Pioneer 9294 (P9294RR), Pioneer 9333 (P9333RR), Pioneer 9344 (P9344RR), 2626RR, and Pioneer 9363 (P9363RR). In Iowa the soil type was a silt loam; in South Dakota the soil was a loam. The plots were drill-sown with weeds and the crop prior to application of the herbicides. The herbicides were applied alone or in combination 18 and 20 days after sowing in South Dakota and Iowa respectively. At the time of application the weeds were between about 1.5 and about 6 inches tall (3.8 and 15.3 cm respectively) and the soybean was at the 2 leaf growth stage (about 4 to 6 inches tall, i.e. about 10 to 15 cms). In addition, weeds were also drilled just prior to planting (The same day as the application in S.Dakota and the previous day in Iowa) in order to determine whether the isoxazole was effective in controlling these weeds which emerged after the application of glyphosate. 2 Replicates were performed. Percentage phytotoxicity was assessed visually 26- 28 days after treatment (DAT). 6 - 15 - The following results were obtained. In the tables that follow the weeds are identified by their Bayer codes and the crops by the codes used elo The dose rates are given in grammes of active ingredient per hectare (g/ha) of the salt and the figures in parenthesis indicate the expected figure of control according to the Colby formula (Colby S.R., 1967, Weeds 15, 20-22). "First planting" refers to the weeds which had emerged at the time of application of the isoxazole and glyphosate. "Second planting" refers to the weeds which were sown just before the herbicides were applied. O 99/23886 - 16 - Tahle 1 - Iowa 28 DAT - First planting Table 2 - Iowa 28 DAT - Second planting Table 5 - Effect on soybean (27 DAT) SOYBEAN VARIETY Note: ABUTH = Abutilon theophrasti AMATA = Amaranthus rtidis CHEAL = Chenopodium album HELAN = Helianthus annus IPOSS = Ipomoea purpurea SETFA = Setaria faberii SETGL = Setaria glauca SETVI = Setaria viridi AMARA = Amaranthus retroflexus IPOHE = Ipomoea hederacea While the invention has been described in terms of various preferred embodiments, the skilled artisan will appreciate that various modifications, substitutions, omissions, and changes may be made without departing from the spirit thereof. Accordingly, it is intended that the scope of the present invention be limited solely by the scope of the following claims, including equivalents thereof.

Claims: WE CLAIM 1. A method for the control of weeds at a crop locus, said method comprising the application of an effective amount of: (a) a glyphosate herbicide which is glyphosate or a derivative thereof; and (b) at least one HPPD-inhibiting herbicide; wherein the crop locus comprises a crop tolerant to said glyphosate herbicide. 2. A method according to claim 1 wherein the crop is tolerant to glyphosate and said HPPD-inhibiting herbicide. 3. A method according to claim 1 wherein the application is post emergence of the crop. 4. A method according to claim 3 in which the crop is selected from maize, sugarcane, soybean, cotton, canola and clover. 5. A method according to claim 4 in which the crop is maize or soybean. 6. A method according to claim 5 in which the crop height is less than about 15 cm and the weed height is less than about 10 cm. 7. A method according to claim 1 in which the application rate of the glyphosate herbicide is from about 400 to about 1200g acid equivalent (a.e)/ha. 8. A method according to claim 7 in which the application rate of the HPPD-inhibiting herbicide is from about 20g/ha to about 500g ha. 6 21 9. A method according to claim 1 in which the weight ratio of (a):(b) is from about 0.8: 1 to about 60: 1. 10. A method according to claim 1 in which the glyphosate derivative is a salt selected from the mono isopropylammonium salt, the sodium salt and the trimesium salt. 11. A method according claim 1 in which the HPPD-inhibiting herbicide is a 4-benzoylisoxazole herbicide. 12. A method according to claim 11 in which the 4-benzoylisoxazole herbicide has the formula (I): (I) wherein R is hydrogen or -CO R 3 ; Rl is Cι_4 alkyl or C3. cycloalkyl optionally substituted by C\. alkyl; R 2 is selected from halogen, nitro, cyano, -S(O)pR^, -(CR 4 R5) q S(O) p R6, -N(R 7 )SO 2 R 6 , C\. 6 alkoxy, -OSO 2 R 6 , C haloalkoxy, Cι_4 alkyl and Cι_4 haloalkyl; or two groups R 2 , on adjacent carbon atoms of the phenyl ring may, together with the carbon atoms to which they are attached, form a 5 or 6 membered saturated or unsaturated heterocyclic ring containing up to three ring heteroatoms selected from nitrogen, oxygen and sulfur, which ring may be optionally substituted by one or more groups selected from halogen, nitro, -S(O)pR^, Cι_4 alkyl, C1.4 alkoxy, Cι_4 haloalkyl and C1. haloalkoxy; it being understood that a sulphur atom, where present in the ring, may be in the form of a group -SO- or -SO2-; n is an integer from one to five: p is zero, one or two: q is one or two: where q is two the groups (CR 4 R^) may be the same or different 6 - 22 - R 3 is Cι_4 alkyl: R 4 and R^ are independently hydrogen or C \^ alkyl; R^ is Cι_4 alkyl, or phenyl or benzyl, each of phenyl and benzyl optionally bearing from one to five substituents which may be the same or different selected from the group consisting of halogen, C \ .4 alkyl, Cj_4 alkoxy, C\^ haloalkyl, Cj_4 haloalkoxy, nitro and -S(O)pCH3; and R 7 is hydrogen or C1.g alkyl; or an agriculturally acceptable salt thereof. 13. A method according to claim 12 having one or more of the following features: R is hydrogen or -CO2CH2CH3; R! is cyclopropyl: R 2 is halogen, -S(O) p Me, trifluoromethyl, Cj_4 haloalkoxy, Cj_4 alkoxy or -CH 2 S(O) p Me; n is two or three. 14. A method according to claim 13 in which either n is three and the groups (R 2 ) n occupy the 2,3 and 4-positions of the benzoyl ring; or n is two and the groups (R-) n occupy the 2 and 4- positions of the benzoyl ring. 15. A method according to claim 12 in which the compound of formula (I) is 5-cyclopropyl-4-(2-methylsulphonyI-4- trifluoromethyl)benzoyIisoxazole; 4-(2-chloro-4- methylsulphoπyl)benzoyl-5-cyclopropylisoxazole; 4-(4-chloro-2- methylsulphonyl)benzoyl-5-cyclopropylisoxazole; 4-(4-bromo-2- methylsulphonyl)benzoyl-5-cyclopropylisoxazole; ethyl 5-cyclopropyl- 4-(2-methylsulphonyl-4-trifluoromethyl)benzoylisoxazole-3- carboxylate: 4-[4-bromo-2-(methylsulphonylmethyl)benzoyl]-5- cyclopropylisoxazole; 4-(4-bromo-3-(2,2-difIuoroethoxy)-2- methylsulphonylbenzoy!]-5-cyclopropylisoxazole: 5-cyclopropyl-4-[2,2- 6 - 23 - difluoro-4-(methanesulphonylmethyl)-l,3-benzodioxol-5-oyl]isoxazole and 5-cyclopropyl-4-(4-fluoro-3-methoxy-2- methy Isu Iphony 1 benzoyl )isoxazole. 16. A method according to claim 15 in which the compound of formula (I) is 5-cyclopropyl-4-(2-methylsulphonyl-4- trifluoromethy benzoylisoxazole or 5-cyclopropyl-4-(4-fluoro-3- methoxy-2-methylsulphonylbenzoyl)isoxazole. 17. A method according to claim 1 in which the HPPD-inhibiting herbicide is a 2-benzoylcyclohexane-l,3-dione derivative. 18. A method according to claim 17 in which the 2-benzoyl- cyclohexane- 1 ,3-dione derivative has the general formula (II): (ID wherein R 11 is hydrogen, Cj_6 alkyl, or phenyl; X is oxygen or -S(O) z where z is zero, one or two; R 12 , R 13 , R 14 , R 15 , R 16 and R 17 independently represent hydrogen or Ci _6 alkyl; or Rl2 and R* 4 , together with the carbon atoms to which diey are attached, form a three to five membered saturated carbocyclic ring; or R! 2 and R^ together form an ethylene radical; R! 8 is nitro, halogen, cyano, Cj_ alkyl, Cj_4 haloalkyl. Cj^ alkoxy, C j .4 haloalkoxy or -S(O) 2 R 20 : R ' is halogen, nitro. cyano, C j .4 alkyl, C i _4 alkoxy, C i _4 haloalkyl. C[_4 haloalkoxy. -NR 2 1 R 22 , -S(O) z R 23 , -OSO2R 23 , -(CR R 2 5) a S(O) z R 23 or -NR 2 6sO 2 R 23 , e is an integer from one to four; R 2 ^ represents C \ .4 alkyl ; R 21 , R 22 , R 24 , R 25 and R 26 independently represent hydrogen or C\ .4 alkyl: R 23 is C 1.4 alkyl, phenyl or benzyl, each of phenyl and benzyl optionally bearing from one to five substituents which may be the same or different selected from the group consisting of halogen, C \ .4 alkyl, Cι_4 alkoxy, C 1.4 haloalkyl, Cj_ haloalkoxy, nitro and -S(O) z CH3; a is one or two, where a is two the groups (CR 2 R 2 ^) may be the same or different; an enoiic tautomeric form thereof, or an agriculturally acceptable salt or metal complex thereof. 19. A method according to claim 18 in which the compound of formula (II) has one or more of the following features: R 1 1 is hydrogen and X is oxygen; Rl 2 , Rl 3 , Rl 6 and Rl 7 each represent hydrogen, and R 1 4 and Rl 5 independently represent hydrogen or methyl; Rl8 is halogen or nitro; Rl 9 is Cj.4 alkoxy or -S(O) z R 23 or -OSO2R 23 , where R 23 is Ci .4 alkyl; e is one or two. 20. A method according to claim 19 in which either e is one and R 1 occupies the 4-position of the benzoyl ring; or e is two and the two groups R ' 9 occupy the 3- and 4-positions of the benzoyl ring. 21. A method according to claim 20 in which the compound of formula (II) is 2-(2-chloro-4-methylsulfonylbenzoyl)cycIohexane-l,3- 6 - 25 - dione; 2-(2'-nitro-4'-methylsulfonylbenzoyl )cyclohexane- 1.3-dione; 2- (2'-nitro-4'-methylsulfonyloxybenzoyl)cyclohexane- 1 ,3-dione; or 2-(2'-chloro-3-ethoxy-4'- ethylsulfonyIbenzoyl)-4-methylcyclohexane- 1.3-dione. 22. A method according to claim 2 in which the HPPD-inhibiting herbicide is a 2-cyano-l,3-dione herbicide having the general formula (1TJ): W) wherein R 3 ^ is C 1.4 alkyl or C3.6 cycloalkyl optionally substituted by C\. alkyl; R 3 is selected from halogen, nitro, cyano, -S(O) r R 32 , -(CR 3 R 3 ) v S(O) r R 32 , -N(R 35 )SO 2 R 32 , C { . 6 alkoxy, -OSO 2 R 32 , C j .4 haloalkoxy, Cj^ alkyl and C 1.4 haloalkyl: or two groups R 3 1, on adjacent carbon atoms of the phenyl ring may, together with the carbon atoms to which they are attached, form a 5 or 6 membered saturated or unsaturated heterocyclic ring containing up to three ring heteroatoms selected from nitrogen, oxygen and sulfur, which ring may be optionally substituted by one or more groups selected from halogen, nitro, -S(O) r R 32 , Cj_4 alkyl, alkoxy, Cj_4 haloalkyl and C ] haloalkoxy, it being understood that a sulphur atom, where present in the ring, may be in the form of a group -SO- or -SO 2 - t is an integer from one to five: r is zero, one or two; R 32 is Ci .4 alkyl, or phenyl or benzyl, each of phenyl and benzyl optionally bearing from one to five subsiituents which may be the same 6 - 26 - or different selected from the group consisting of halogen. Cj4 alkyl, C] 4 alkoxy, Cj haloalkyl, Cj haloalkoxy, nitro and -S(O) r CH3; R 33 , R 34 and R 35 are independently hydrogen or C14 alkyl; v is one or two; where v is two the groups (CR 33 R 34 ) may be the same or different an enoiic tautomeric form thereof, or an agriculturally acceptable salt or metal complex thereof. 23. A method according to claim 22 having one or more of the following features: R 3 0 is 1-methylcyclopropyl or cyclopropyl; R 3 1 is selected from halogen, -S(O) r Me, trifluoromethyl, C1 haloalkoxy, C1 alkoxy and -CH 2 S(O) r Me; t is one, two or three; and one of the groups R 3 1 is -S(O) r Me. 24. A method according to claim 23 in which the compound of formula (HI) is 3-cyclopropyl-2 -cyano- l-(2-methylsulphonyl-4- trifluoromethylphenyl)propan-l,3-dione; l-(2-chloro-4- methylsulphonylphenyI)-2-cyano-3-cyclopropylpropan- 1 ,3-dione; 2-cyano-3-cyclopropyl- 1 -(4-fluoro-3-methoxy- 2-methylsulphonylphenyl)propan-l,3-dione; or l-(4-chloro-2- methylsulphonylphenyl)-2-cyano-3-cyclopropylpropan- 1 ,3-dione> 2-cyano-l- (4- πethylsulphonyl-2--trif luorαnethylpnerryl) -3- (l-methylcyclopropyl) prqpan-l,3-dione. 25. A method for the control of weeds at a soybean or com crop locus, said method comprising the post-emergent application to said crop of an effective amount of: (a) the mono isopropylammonium salt of glyphosate; and (b) a 4-benzoylisoxazole selected from 5-cyclopropyl-4-(2- methylsuIphonyl-4-trifluoromethyl)benzoyIisoxazole and 5-cyciopropyi- 4-(4-fIuoro-3-methoxy-2-methylsulphonylbenzoyl)isoxazole: wherein the crop is tolerant to glyphosate and said 4-benzoylisoxazole. 26. A composition comprising a synergistic herbicidally effective amount of: (a) a glyphosate herbicide which is glyphosate or a derivative thereof; and (b) a 4-benzoylisoxazole derivative as defined in claim 12; in association with an agriculturally acceptable diluent or carrier. 27. A composition according to claim 26 in which (b) is 5- cyclopropyl-4-(4-fIuoro-3-methoxy-2- methylsulphonylbenzoyl)isoxazole. The invention relates to a method for the control of weeds at a crop locus, said method comprising the application of an effective amount of: (a) a glyphosate herbicide which is glyphosate or a derivative thereof; and (b) at least one HPPD-inhibiting herbicide; wherein the crop is tolerant to glyphosate and optionally the HPPD-inhibiting herbicide.

Inventors: DE ROSE RICHARD, PALLETT KEN, PELISSIER BERNARD, SAILLAND ALAIN, VRABEL THOMAS EDWARD, DE ROSE, RICHARD, PALLETT, KEN, PELISSIER, BERNARD, SAILLAND, ALAIN, VRABEL, THOMAS, EDWARD
Applicants: PALLETT KEN, PELISSIER BERNARD, RHONE POULENC AGROCHIMIE, ROSE RICHARD DE, SAILLAND ALAIN, VRABEL THOMAS EDWARD, DE ROSE, RICHARD, PALLETT, KEN, PELISSIER, BERNARD, RHONE-POULENC AGRO, SAILLAND, ALAIN, VRABEL, THOMAS, EDWARD
Application year: 1998
Main classification: A01N57
IPC codes: A01N57