GB2512112A - Compositions and methods for controlling herbicide resistant weeds - Google Patents

Abstract

A composition comprising (i) a herbicide; and (ii) a compound of formula I, wherein R1 is a C1 to C12 alkyl; and R2 is selected from H and a C1 to C5 alkyl. In one embodiment, and with reference to the compound of Formula I, R1 is a propyl group and R2 is a methyl group. Suitably, the herbicide is a phenoxy herbicide, such as diclofop, or a derivative thereof. The composition can comprise a rapid release formulation of the compound of formula I, and a non-rapid release formulation of the herbicide. The use of a compound of formula I as a herbicide synergist is also claimed. A method of controlling weeds is also claimed, the method comprises contacting the weeds with (i) a compound of formula I and (ii) a herbicide. In one embodiment, the weeds are contacted with a compound of formula I before being contacted with the herbicide. Formula I

Description

COMPOSTTIONS AND METHODS FOR CONTROLL[NGJ HERBTCTDE RESTSTANT

WEEDS

The present application relates to herbicide synergists, in particular to synergists which improve the effectiveness of herbicides against herbicide resistant weeds such as black grass.

Herbicide resistance is become progressively more widespread and has become a serious threat to the future success of weed control using cheniicals.

Of particular concern is the increasing problem of herbicide resistant black grass. Black grass is an annual grass weed that occurs throughout the UK and causes problems for farmers growing cereal crops. A large number of black grass populations have developed resistance to commonly used herbicides and the weed is becoming increasingly common.

the presence of black grass not only has an effect on crop yields, hut it can also result in fungal contamination of crops. In this respect, black grass can often become infected with ergot which can then he transmitted to the crop.

there is, therefore, a need for improved methods and compositions for improving the effectiveness of herbicides against herbicide-resistant weeds, in particular black grass.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a composition comprising (i) a herbicide; and (ii) a compound of formula I or II.

Preferably, the composition is a herbicide composition.

Preferably, the composition comprises a rapid release formulation of the compound of formula I or II, and a non-rapid release formulation of the herbicide.

Preferably, the composition comprises a fomrnlation in which a compound of formula I or II and a herbicide are released simultaneously.

According to another aspect of the present invention, there is provided use of a compound of formula I or II as a herbicide synergist.

In this respect, the term "herbicide synergist" means that the compound of formula I or II is capable of making the herbicide effective against herbicide-resistant weeds, or is capable of making the herbicide more effective against herbicide-resistant weeds and/or herbicide-susceptible weeds.

In this respect, the term "herbicide-susceptible weed" means a weed which is susceptible to action of the herbicide. For example, a herbicide-susceptible weed could he a weed whose growth can be slowed or prevented by a herbicide or which can be killed by a herbicide.

Advantageously, use of a compound of formula I or II as a herbicide synergist means that less herbicide is needed in order to achieve the same results as use of a herbicide alone in relation to herbicide-susceptible weeds.

According to another aspect of the present invention, there is provided use of a compound of formula I or II in combination with a herbicide.

According to another aspect of the present invention, there is provided a method for controlling weeds, the method comprising contacting the weeds with (i) a compound of formula I or II and (ii) a herbicide.

Preferably, the weeds are contacted with a compound of formula I or II before being contacted with the herbicide.

Preferably, the weeds are contacted with a compound of formula I or II at least about minutes before being contacted with the herbicide, preferably at least about 1 hour, preferably at least about 2 hours, preferably at least about 3 hours, for example about 4 hours before being contacted with the herbicide.

Preferably, the weeds are contacted with a compound of formula I or II and the herbicide simultaneously.

According to another aspect of the present invention, there is provided a method for controlling weeds, the method comprising contacting the weeds with a composition of the present invention.

Preferably, the herbicide is a phenoxy herbicide or a derivative thereof Preferably, the herbicide is selected from a phenoxyacetic herbicide. phenoxybutyric herbicide or phenoxypropionic herbicide, or a derivative thereof Preferably, the herbicide is an aryloxyphenoxypropionic herbicide, or a derivative thereof.

Pregerably, the herbicide is selected from 2,4-dichlorophenoxyacetic acid. 4-(2,4- dichlorophenoxy)butyric acid, dichlorprop. fenoprop. MCBA (2-methyl-4-chlorophenoxyacetic acid). MCPB (2.4-MCPB, 4-(4-chloro-o-tolyloxy)butyric acid), 2,4,5-trichlorophenoxyacetic acid, MCPP (2-(2-Methyl-4-chIorophenoxypropionic acid) or diclofop.

Preferably, the derivative thereof is an ester or a salt, for example an ethyl, methyl, hutyl, isohutyl ester thereof or an amine or sodium salt thereof Preferably, the herbicide is diclofop or diclofop-methyl.

Preferably, the weeds are herbicide resistant weeds or herbicide susceptible weeds.

Preferably, the weeds are broad-leaf plants.

Preferably, the weeds are selected from black grass, dandelion, buttercup, clover, daisy, wild radish, wild mustard, Paterson's curse, blue mustard, hairy nightshade, field pennycress, horseweed, knotweed. Japanese knotweed, pigweed, black medick, smartweed, common mallow, prickly lettuce, spreading atriplex, redroot pigweed, thistle, shepherd's purse, field violet, sunflower, hairy nightshade, flower of an hour. common ragweed. giant ragweed, field horsetail, wild buckwheat, tufted etch, wild vetch, velvet leaf. waterhemp, wild carrot, white cockle, charlock or chickweed.

Preferably, the weeds are black grass.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to compositions and methods for controlling weeds and herbicide-resistant weeds. In particular, the invention relates to novel compositions comprising a herbicide and a herbicide synergist.

Examples of the present invention will now be described with reference to the accompanying figures. in which Figure 1 shows a graph comparing the results obtained with PBO and EN-126 on diclofop susceptible and diclofop resistant black grass.

VyTithin this specification embodiments have been described in a way which enables a clear and concise specification to he written, hut it is intended and will he appreciated that embodiments may be variously combined or separated without parting from the invention.

VyTithin this specification. reference to a compound of formula I means a compound having the following structure: wherein, R1 is a Cl to C12 alkyl; and K2 is selected from H and a Cl to C alkyl.

Within this specification, reference to a compound of formula II means a compound having the following structure: Formula II Within this specification, the term "EN 126" or "126" means a compound of formula II.

Within this specification, the term "herbicide-resistant weed", means a weed which shows at least some resistance to a herbicide. The resistance may be partial or complete and it will be appreciated that all degrees of resistance are included the meaning of this term, whether they he very low resistance, low resistance, high resistance, very high resistance or total resistance.

Within this specification, the term "about" means plus or minus 20%. more preferably plus or minus 10%, even more preferably plus or minus 5%. most preferably plus or minus 2%.

Within this specification, it will be appreciated that reference to the term "controlling weeds" includes reference to killing or inhibiting the growth of weeds. Preferably, the term means killing or inhibiting the growth of all or a substantial proportion of a population of weeds contacted with a composition of the present invention.

The terni "substantial portion" may mean at least about 50%. at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 98%, or at least about 99%.

As described herein, the composition of the invention may comprise a rapid release formulation of the compound of formula I or II, and a non-rapid release formulation of the herbicide. Rapid release and non-rapid release formulations are described in detail in International patent application number PCI'/0B03/0l 861, published as W003/092378 on 13 November 2003.

For example, the rapid release formulation and the non-rapid (sustained) release formulation may he comprised in the composition in physical admixture. Alternatively, the rapid release formulation and the non-rapid release formulation may be administered separately, but be brought into contact with the weed at about the same time, avoiding the need to revisit the site of the weed in order to apply the second of the two formulations. Both formulations would thereby conic into contact with the weed within the order of seconds, preferably within 10 seconds and more preferably, within one or two seconds, of each other rather than in the order-of minutes or longer. Preferably, the formulations are administered simultaneously.

the rapid release formulation is suitably any standard herbicide formulation known to those skilled in the art or yet to he discovered and suitable for the purpose. Such formulations include, for example. wettable powders, granulates, emulsifiable concentrates and ultra-low volume formulations to which water can be added to form an emulsion, a suspension and the like. Preferably, the rapid release formulation, comprising a compound of formula I or II, is in the form of an emulsifiable concentrate.

The non-rapid release formulation is suitably any non-immediate release formulation known in the art or yet to be discovered, such as sustained, controlled or slow release formulations suitable for the purpose. Preferably, the non-rapid release formulation is one that prevents an effective dose of the herbicide from being released or coming into effective contact with the weed or its target in the weed until the compound of formula I or II has at least begun its effect on its target in the weed.

Suitably, the non-rapid release formulation prevents release of the herbicide or contact thereof with the weed for at least about 30 minutes. preferably at least about hour, preferably at least about 2 hours, preferably at least about 3 hours, for example about 4 hours after application of the composition. Such formulations include, for example, the herbicide encapsulated in a degradable capsule and preferably comprise micro-encapsulation technology.

The non-rapid release formulation preferably comprises an amount equivalent to a standard dosage of the herbicide.

The amount of the compound of formula I or II should be sufficient to prevent or reduce the resistance of the weed(s) to the herbicide and will depend on weed size, degree of resistance etc, hut is determinable by those skilled in the art.

Ihe weed(s) against which the composition of the invention is/are directed can he any which are known to offer at least sonic resistance to a herbicide and which it is considered necessary to disable and/or kill. Examples include those that reduce crop yields, damage crops or otherwise reduce the commercial or other value of crops.

In one example, the weeds(s) may include one or more of black grass, dandelion, buttercup, clover, daisy, wild radish, wild mustard, Paterson's curse, blue mustard, hairy nightshade, field pennycress, horseweed, knotweed, Japanese knotweed, pigweed, black niedick, smartweed, common mallow, prickly lettuce, spreading atriplex, redroot pigweed.

thistle, shepherd's purse, field vi&et, sunflower, hairy nightshade, flower of an hour, common ragweed, giant ragweed. field horsetail. wild buckwheat, tufted vetch, wild vetch,

S

velvet leaf, waterhemp. wild carrot, white cockle, charlock and chickweed.

For administration to the surface of the weed(s), any method known in the art for application of a herbicide or the like to a weed may be used.

Fxamples of such methods include spraying by ground or aerial application. For administration to crops, particularly over vast areas, it is preferred to spray a composition comprising a suspension or emulsion of one or both of the formulations in water, optionally also comprising a surfactant or other excipients, or an ultra-low volume (omitting the water) composition. supplied in a tank, such as one adapted to be transported by aircraft or by ground rig (such as tractor, tank or boom spray).

The rate of administration of the compositions according to the invention will accord with known or approved (registered) rates of the active ingredients of each of the formulations.

Compounds of the present invention may be synthesized according to the methods described below.

Compounds of formula I, in which R' is a Ci to C12 alkyl, and R2 is selected from Fl and a Ci to C alkyl.

(Formula I) can be prepared by known chemical reactions such as, for example: A) Condensation (etherification) of the halogenomethyl derivative of formula IlL in which RI represents a Cl-Cu alkyl, and Hal is C! or Br, Hal (Formula TIT) with the suitable alcohol of a compound of R=C-CH2OH (Formula IV), in which R2 represents H or a C1-C5 alkyl, in the presence of a suitable base such as sodium or potassium hydroxide, sodium or potassium carbonate in neat or in an inert aromatic solvent such as toluene or xylene at a temperature between 60°C and 140°C; neat or in toluene are preferred.

B) Condensation (etherification) of the halogenomethyl derivative of formula III in which Ri represents a C1-C12 alkyl, and Hal is Cl or Br, <H2 Hal (Formula II!) with the suitable alkaline alcoholate of a compound of R2=C-CH2OMe (Formula V) in which R2 represents H or a CI -C5 alkyl and Me is sodium or potassium, in a suitable solvent such as N,N-dimethylformamide, N,N-dimethylacetanude, N-methyl pyrrolidone, tetrahydrofurane, 2-methyltetrahydrofisrane or dioxane at a temperature between 50°C and 150°C. A temperature between 50°C and 80°C is preferred.

C) Condensation (etherification) of the hydroxymethyl derivative of formula VI, in which RI represents aCl-C12 alkyl, °:H2oH (Formula VI) with the suitable alkyne halogenide of a compound of R2C-CH2Hal (Formula VII) in which R2 represents H or a Cl-Cs alkyl and Hal is Cl. Br or I (preferably Br) in the presence of a suitable base such as sodium hydride and in a suitable solvent such as N,N- dirnethylforniarnide. N,N-dimethylacetarnide. N-methylpyrrolidone, tetrahydroftirane. 2-methyltetrahydrofurane or dioxane at a temperature between 50°C and 150°C. Temperatures between 50°C and 80°C are preferred.

D) Condensation (etherification) of the halogenomethyl derivative of formula III. in which Ri represents a Cl-C12 alkyl and Hal is Cl or Br, Ofl:H2 Hal (Formula Ill) with the suitable alcohol of a compound of R2=C-CH2OH (Formula IV) in which R2 represents H or a Cl -C alkyl, in the presence of a metal oxide such as zinc oxide and a suitable apolar aprotic solvent such as dichloromethane or dichloroethane and at temperatures Ii between 20°C and 90°C, as described in US 6,320,085. Temperatures between 20°C and 40°C are preferred.

E) Condensation (etherifleation) of the hydroxymethyl derivative of formula VI, in which RI represents a Cl-Cl 2 alkyl, Ofl:H2OH (Fornrnla VI) with the suitable alcohol of a compound of R2HCCH2OH (Formula IV) in which R2 represents H or a Cl -Cs alkyl, in the presence of an efficient amount of a heterogeneous catalyst such as a zeolite in acidic form alone or in combination with a mineral acid as described in US 6,608,232. The reaction is preferably carried out in neat at temperatures between 50°C and 100°C.

Another possible synthetic pathway is to get compounds of formula I where 1<2 is hydrogen by the known and shown condensation reactions with an alkylation reagent of a compound of R2-O-S02-O-R2 (Formula VIII) or R2-I-Ial (Formula IX). in which R2 represents a Cl-Cs alkyl and Hal is Cl. Br or I. in the presence of an anionisation agent such as amide base, a metallic alcoholate or an alkali metal as described in US 6,881,869.

the compounds of formula III can he obtained from compounds of formula X, (Formula X) by the well known reaction of halogenomethylation of a compound of formula X with formaldehyde or paraformaldehyde in the presence of aqueous concentrated hydrochloric acid or hydrobromic acid as described, for example, in US 2,878,265 and US 2,878,266.

The compounds of formula VI can be obtained from the compounds of formula III by reaction with the suitable alkaline acetate and subsequent hydrolysis as described, for example. in tJS 7,402,709.

the compounds of formula X can he obtained through the well known step of acylation of henzodioxole ring and subsequent reduction as described in ITS 6,342,613.

Synthesis of 5 -(but-2-ynvloxvmethyl)-6-propyl-benzo [1.31 dioxole (EN 126) In a flask equipped with a stirrer, 16 g (0.41 moles) of sodium hydride (60% w/w in mineral oil) and 400 ml of N,N-dimethylformamide are placed. the mixture is cooled to 0°C- 5°C under stirring and a nitrogen atmosphere. A solution of 75g (0.38 moles) of 5- (hydroxymethyl)-6-propyl-henzo[1,3jdioxole in 80 nil of N,N-dimethylformarnide is then added slowly and stirred for a further hour at room temperature.

The mixture is then cooled to 0°C.-5°C and 50.5 g (0.38 moles) of l-hromo-2-hutyne are added slowly keeping the temperature at 0°C-S°C. The reaction is then stirred for a further two hours at room temperature.

The mixture is then cooled to 5°C and 1000 ml of water is added and extracted with diisopropyl ether (3x 200 ml). Ihe organic phases are collected, dried on anhydrous sodium sulfate, filtered and evaporated u.v. (30°C/21 mbar). The oil residue is then distilled at 118°C.- 125°C /0.3 mbar obtaining 63.3 g of an oil product (OC title 98.8%) whose NMR and MS analyses correspond to those of the aforementioned compound.

According to one aspect of the present invention, there is provided a method for synthesizing a compound of formula I or II, for example as exemplified herein.

The present invention therefore further provides: (a) the use of a composition according to the invention in the treatment or prevention of herbicide resistance; (b) the use of a composition according to the invention in the treatment or prevention of damage to crops by a weed; (c) the use of a composition according to the invention in weed control; and (d) a method for preparing a composition according to the invention, which method comprises bringing a compound of formula I or II and a herbicide into physical admixture.

EXAMPLES

Methods Petri dishes were prepared each with 3 filter papers Whatnian No.1, 90 mm. 75 susceptible or 75 resistant black grass seeds were placed into the dishes and 5.5 ml KNO3 soln (2g/L) was applied to each dish using a syringe.

Dishes were placed in clear polythene bags and into incubator. Stacks of plates were moved around every 1-2 days to ensure uniform environment.

After 6 days of incubation, 25 germinated seeds (2-4 mm roots, no shoots) were placed into fresh petri dishes containing 7 ml. of either KN03 (2g/lj, PBO(2g/L) in KN03, or 126(2g/L) in KNO3 Dishes were placed in an incubator (1 TIC, 14:10 day:night for 24 hrs.

After 24 hrs seeds were applied to further petri dishes containing either 10 ppm herbicide in KNO3, PBO (0.2%) +10 ppm herbicide, or 126 (2%) +10 ppm herbicide.

Plates were placed in an incubator for 9 days, during which stacks were moved around to provide equivalent environment.

After 9 days the number of seeds with shoots longer than 2 cm was measured.

To provide replicates there were 4 dishes for each treatment.

The herbicide used was diclofop-methyl.

Results The results are shown in Figure 1 from which it will be seen that the use of 126 in combination with the herbicide resulted in surprisingly better results in relation to both herbicide resistant and herbicide susceptible weeds when compared with the results obtained with PBO.

It should be understood that various changes and modifications to the presently preferred embodiments described herein will he apparent to those skilled in the art. Such changes and modifications can he made without departing from the spirit and scope of the present invention and without diminishing its attendant advantages. It is therefore intended that such changes and modifications are covered by the appended claims.

Ihe content of all references cited herein are incorporated herein by reference in their entirety.

Claims (18)

1. CLAIMS1. A composition comprising (i) a herbicide; and (ii) a compound of formula I. Formula I wherein.Ri is a Cl to C12 aiRy!; and 1(2 is selected from H and a Cl to CS alkyl.
2. 2. A composition according to claim 1. wherein the compound of formula I is a compound of formula II, Formula II.
3. 3. A composition according to claim 1 or 2, wherein the composition is a herbicide composition.
4. 4. A composition according to any preceding claim comprising a rapid release formulation of the compound of formula I or II, and a non-rapid release formulation of the herbicide.
5. 5. A composition according to any preceding claim, wherein the herbicide is a phenoxy herbicide or a derivative thereof
6. 6. A composition according to claim 5, wherein the herbicide is diclofop or a derivative thereof
7. 7. Use of a compound of formula I or II as a herbicide synergist.
8. 8. Use of a compound of formula I or II in combination with a herbicide.
9. 9. Use according to claim 7 or 8, wherein the herbicide is a phenoxy herbicide or a derivative thereof
10. 10. Use according to claim 9, wherein the herbicide is diclofop or a derivative thereof
11. 11. A method for controlling weeds, the method comprising contacting the weeds with (i) a compound of formula I or II and (ii) a herbicide.
12. 12. A method according to claim 11, wherein the weeds are contacted with a compound of formula I or II before being contacted with the herbicide.
13. 13. A method according to claim 11 or 12. wherein the herbicide is a phenoxy herbicide or a derivative thereof
14. 14. A method according to claim 13, wherein the herbicide is diclofop or a derivative thereof.
15. 15. A method for controlling weeds, the method comprising contacting the weeds with a composition according to any of claims 1 to 6.
16. 16. A method according to any of claims 11 to 15, wherein the weeds are herbicide-resistant weeds or herbicide-susceptible weeds.
17. 17. A method according to any of claims 11 to 16. wherein the weeds are broad-leaf plants.
18. 18. A method according to any of claims 11 to 17, wherein the weeds are selected from one or more of black grass. dandelion. buttercup. clover, daisy, wild radish, wild mustard, Paterson's curse, blue mustard, hairy nightshade, field pennycress. horseweed. knotweed.Japanese knotweed. pigweed, black medick, smartweed, common mallow, prickly lettuce, spreading atriplex, redroot pigweed, thistle, shepherd's purse, field violet. sunflower, hairy nightshade, flower of an hour, common ragweed, giant ragweed, field horsetail, wild buckwheat, tufted vetch, wild vetch, velvet leaf waterhemp. wild carrot, white cockle, charlock and chickweed.