WO2014147387A1

WO2014147387A1 - Compositions and methods for controlling herbicide resistant weeds

Info

Publication number: WO2014147387A1
Application number: PCT/GB2014/050852
Authority: WO
Inventors: Graham David Moores; Valentina MAESTRI
Original assignee: Rothamsted Research Limited
Priority date: 2013-03-21
Filing date: 2014-03-18
Publication date: 2014-09-25
Also published as: GB2512112B; EP2975933A1; GB201305166D0; GB2512112A

Abstract

Provided are compositions comprising (i) a herbicide; and (ii) a compound of formula I or II, preferably wherein the composition is a herbicide composition. Also provided is use of a compound of formula I or II as a herbicide synergist and use of a compound of formula I or II in combination with a herbicide. Further provided are methods for controlling weeds.

Description

COMPOSITIONS AND METHODS FOR CONTROLLING HERBICIDE RESISTANT

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 chemicals.

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, but it can also result in fungal contamination of crops. In this respect, black grass can often become infected with ergot which can then be 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 formulation 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 be 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 30 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-chlorophenoxy)propionic acid) or diclofop.

Preferably, the derivative thereof is an ester or a salt, for example an ethyl, methyl, butyl, isobutyl 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 vetch, 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.

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

Within this specification, reference to a compound of formula I means a compound having the following structure:

wherein,

R¹ is a C l to Cl2 alkyl; and

R is selected from H and a Cl to C5 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 be 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 term "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 PCT/GB03/01861, published as WO03/092378 on 13 November 2003.

For example, the rapid release formulation and the non-rapid (sustained) release formulation may be 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 come 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 be 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 1 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, but is determinable by those skilled in the art.

The weed(s) against which the composition of the invention is/are directed can be any which are known to offer at least some 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 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.

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.

Examples 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.

1 2

Compounds of formula I, in which R is a C l to C\2 alkyl, and R is selected from

H and a Cl to C5 alkyl,

(Formula I) can be prepared by known chemical reactions such as, for example:

A) Condensation (etherification) of the halogenomethyl derivative of formula III, in which Rl represents a C1-C12 alkyl, and Hal is CI or Br,

(Formula III) with the suitable alcohol of a compound of R≡C-CH20H (Formula IV), in which R2 represents H or a C 1 -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 Rl represents a C 1 -C12 alkyl, and Hal is CI or Br,

(Formula III) with the suitable alkaline alcoholate of a compound of R2≡C-CH20Me (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, Ν,Ν-dimethylacetamide, N-methyl pyrrolidone, tetrahydrofurane, 2-methyltetrahydrofurane 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 Rl represents a Cl-Cl 2 alkyl,

(Formula VI) with the suitable alkyne halogenide of a compound of R2≡C-CH2Hal (Formula VII) in which R2 represents H or a C1 -C5 alkyl and Hal is CI, 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- dimethylformamide, Ν,Ν-dimethylacetamide, N-methylpyrrolidone, tetrahydrofurane, 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 Rl represents a C l -Cl2 alkyl and Hal is CI or Br,

(Formula III) with the suitable alcohol of a compound of R2=C-CH20H (Formula IV) in which R2 represents H or a C1-C5 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 between 20°C and 90°C, as described in US 6,320,085. Temperatures between 20°C and 40°C are preferred.

E) Condensation (etherification) of the hydroxymethyl derivative of formula VI, in which Rl represents a Cl-C alkyl,

(Formula VI) with the suitable alcohol of a compound of R2≡C-CH20H (Formula IV) in which R2 represents H or a C1-C5 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 R2 is hydrogen by the known and shown condensation reactions with an alkylation reagent of a compound of R2-O-SO2-O-R2 (Formula VIII) or R2-Hal (Formula IX), in which R2 represents a C1-C5 alkyl and Hal is CI, 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 be 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 US 7,402,709.

The compounds of formula X can be obtained through the well known step of acylation of benzodioxole ring and subsequent reduction as described in US 6,342,613.

Synthesis of 5-(but-2-ynyloxymethyl)-6-propyl-benzori l 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 Ν,Ν-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-benzo[l,3]dioxole in 80 ml of Ν,Ν-dimethylformamide 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 1 -bromo-2-butyne are added slowly keeping the temperature at 0°C-5°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). The 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 1 18°C- 125°C /0.3 mbar obtaining 63.3 g of an oil product (GC 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 Whatman No. l, 90 mm. 75 susceptible or 75 resistant black grass seeds were placed into the dishes and 5.5 ml N0₃ 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 NO₃ (2g/L), PBO(2g/L) in NO₃, or 126(2g/L) in KN0₃

Dishes were placed in an incubator (17°C, 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 be apparent to those skilled in the art. Such changes and modifications can be 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.

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

Claims

1. A composition comprising (i) a herbicide; and (ii) a compound of formula I,

Formula I wherein,

Rl is a CI to C12 alkyl; and

R2 is selected from H and a CI to C5 alkyl.

2. A composition according to claim 1 , wherein the compound of formula I is a compound of formula II,

Formula II.

3. A composition according to claim 1 or 2, wherein the composition is a herbicide composition.

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. A composition according to any preceding claim, wherein the herbicide is a phenoxy herbicide or a derivative thereof.

6. A composition according to claim 5, wherein the herbicide is diclofop or a derivative thereof.

7. Use of a compound of formula I or II as a herbicide synergist.

8. Use of a compound of formula I or II in combination with a herbicide.

9. Use according to claim 7 or 8, wherein the herbicide is a phenoxy herbicide or a derivative thereof.

10. Use according to claim 9, wherein the herbicide is diclofop or a derivative thereof.

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. A method according to claim 1 1, wherein the weeds are contacted with a compound of formula I or II before being contacted with the herbicide.

13. A method according to claim 1 1 or 12, wherein the herbicide is a phenoxy herbicide or a derivative thereof.

14. A method according to claim 13, wherein the herbicide is diclofop or a derivative thereof.

15. A method for controlling weeds, the method comprising contacting the weeds with a composition according to any of claims 1 to 6.

16. A method according to any of claims 1 1 to 15, wherein the weeds are herbicide- resistant weeds or herbicide-susceptible weeds.

17. A method according to any of claims 1 1 to 16, wherein the weeds are broad-leaf plants.

18. A method according to any of claims 1 1 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.