CA1104843A

CA1104843A - Herbicidal composition

Info

Publication number: CA1104843A
Application number: CA235,478A
Authority: CA
Inventors: Gerald B. Lush; Anthony J. Mayes
Original assignee: Boots Co PLC
Current assignee: Boots Co PLC
Priority date: 1974-09-17
Filing date: 1975-09-15
Publication date: 1981-07-14
Also published as: NL7510866A; BE833218A; SE7510351L; SU736855A3; DK139801C; DD120346A5; HU177800B; ES440973A1; FR2285071A1; DE2540364A1; CS191279B2; JPS5157825A; GB1518672A; ATA707775A; FR2285071B1; BR7505905A; DK412675A; DE2540364C2; IT1047110B; AT343403B

Abstract

ABSTRACT OF THE DISCLOSURE
A novel herbicidal composition, and methods of using it, are disclosed. The composition comprises 4-chloro 2-oxobenzothiazoiin-3-ylacetic acid or a salt or ester thereof and 3 9 6-dichloro-2-picolinic acid or a salt or ester thereof. It has unexpected and advantageous properties in the selective control of weeds in crops, the control of mayweeds and polygonaceous weeds being synergistic, and it exerts good control over a wide variety of other broad-leaf weeds.

Description

This inven-tion relates to a her~icldal composition and a me-thod for controlling weeds by its use.
The compound, 4 chloro-2-oxobenzothiazolin-3-ylacetic acid is a kno~n her~icide described, for example in our British Patent Specification No. 862,226. Also 3,6-dichloro-2-picolinlc acid is a herbicide and is the sub~ect of British Patent Specification No. 1,003,937. It ~s well known from the art that both of these herbic~des can be used as the free acid or in the form of a salt or ester.
The herbicidal composition of the invention comprises 4-chloro-2-oxo~enzothiazolin-3-ylacetic acid or a salt or ester thereof and 3,6-dichloro-2-picolinic acid or a salt or ester : thereof.
We have found that this composition has unexpected and advantageous properties in t~e selective control of weeds in crops, the control of mayweeds and polygonaceous weeds being synergistic. Moreover the composition exerts good control over a wi:de variety of other broad-leaf weeds. The ratio by weight of the active ingredients expressed in terms of the free acids and as the .ratio by weight of 4-chloro-2-oxobenzothiazoline-3-ylacetic acid to 3,6-dichloro-2-picolinic acid can vary widely, for example, within the range of from 100:1 to 1.:3. Preferably the ratio is from 50:1 to 1:2, especially 25:1 to 1:1~ and the most versatile composition contains the active ingredients in a ratio of from la: 1 to 3:1~
Typical salts of these herbicidal acids include alkali

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. . ' ~ ' metla sal-ts such as ~or instance potassium and sodium salts, ammonium salts and salts formed with organic amines~ Oxgan.ic amines which are preferably used to ~orm these salts include those wlth.up to 10 carfion atoms, for example mono-, di and tri-alkylamines such.as eth~lamine, dimethylamine, dieth.~lamine, triethylamine, octyla~ine and 2-et~ylhexylamine; mono-, di and tri-alkanolamines for e.xample ethanolamine, diethanolamine and triethanolamine; and cyclic amines such as morpholine.
Esters of the herb;~cidal acids include those formed with alcohols having up to 10 car~on atoms, espeaially alkanols containing 1 to 4 carhon atoms, such as methanol, ethanol, - propanol and n-butanol; 2-ethylhexanol; 3,5,5-trimethylhexanol;
l-decanol; phen~lalkanols such as ~enzyl al~ohol; alkoxy-substituted alkanols s~uch as 2-but~xyethanol, 2,2'-butoxye-thoxyethanol and propylene glycol butyl ether.
: The composition of the invention preferably contains the active ingredients in the form of the free acids or salts, especiall~ water-soluble salts, f.or example alkalki metal salts or water-solu~le amine salts, or in the form of an ester derived from an alkanol containing 1 to 4 carbon atoms, especially ethanol.
As mentioned above the compos;tion of the invention exerts an unexpectedly high degree of control of mayweeds such as the ; ~atricaria species, ~atricaria :rec~t'ita ~.~ild chamomile), ~atri-caria matricarioides (rayless mayweed~, Tripleurospermum marit~mum ~ inodorum ~centless mayweed), and Anth;emis

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cotula (s-tinking mayweed~ The co~trol of polygonaceous weeds is also unexpectedly high and examples include ~
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aviculare (knotgrass~, ~ ~ (redshank) and Polygonum convolvulus (black ~nd~eed~ rn addition the compositl`on gives excellent control of a wide variety of o-ther broad-leaf weeds such as for example Cheho~od~um- al~um (fat hen), Galium- aparine (cleaversl, Stel~aria me'dia (chickweed), .
Si~apis ar~ensis (charlock~ and Caps~lla bursa-pastoris (shepherd's purse~. These weeds occur in a range of crops and the composition of the invention can ~e employed for instance in cereals, for example wheat, barlëy, oa~s and mai~e; brassicas, for example oilseed rape, cab~age, cauliflower, ~russels sprouts, : swede, turnip and kale; pasture; and flax. Crops for which the compositlon are especially suited are ~heat, barley, oats and oilseed rape.
In the case of ~rassica crops, and in particular oilseed rape, a preferred herbic~dal composltion comprises an alkyl ester of 4-chloro-2-oxobenzothiazolin-3-ylacetic acid and 3,6-dichloro-2-picolinic acid or a salt or ester thereof.
Usually the latter component is present as the acid or as a salt. We have found that the use of an alkyl ester of 4-chloro-2-oxo~enzothiazolin-3-ylacetic acid results in a safer mixture for brassica crops and avoids damage that can occur to the crop.
Preferably the alkyl ester group conta~ns 1 to 4 carbon atoms, for example a methyl, ethyl, propyl or butyl derivative and is ~ especially ethyl.

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~ ~f~ 3 In order to obtain a herbi`cidal composition mixture having a maximum activity against a broad range of weeks, includlng for example grassy ~eeds, one or more additional herbicides can be added to the composition of the i~venti`on. Additional her~icides include propyzamide; methazole; car~etamide; a suBstituted urea for example diuron; dalapon; nitrofen;
napropamide; a triazine ~or example simazine or desmetryne; a substituted acetanilide for example propachlor; a carbamate for example chlorpropham; a th.~olcarhamate ~or example EPTC or tri-allate; a halobenzoic acid for example dicamba; a hydroxybenzo-nitrile for example ioxyn~l or bromoxynil; bentazon; or bromo-fenoxim.
A preferred additional her~icide suitable for a composition intended for use in cereals, is a phenoxyalkanoic acid herbicide or a salt or ester thereof, for example 4-chloro-2-methy.L-phenoxyacetic acid, alpha-~4-chloro-2-methylphenoxy)propionic acid, 2,4-dichlorophenoxyacetic acid and especially alpha-(2,4-dichlorophenoxy~propionic acid, or a salt or ester of any of these acids. When a phenoxy~lkanoic acid is included in the composition an especially suitable ratio range expressed in terms of the free acids 4-chloro-2-oxobenzothiazolin-3-ylacetic acid, 3,6-dichloro-2-picolinic acid and total quantity of phenoxyalkanoic acid, is to to 1:1 to 2:5 to 150, more preferably - in the ran~e of 50 to 1:1 to 2:10 to 100.
The composition of the invention can comprise a dilutent or carrier ~h~ch. may ~e a solid or liquîd, optionally in

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association with a sur~ace-active agent, for example a dispersing agent, emulsifying agent or wetting ayen-t. It can take any form known in the art for the foxmulation of herbicidal compounds, for example, a solution, an aqueous concentrate, a dispersion, a dust, an aqueous emulsi~on, a dispersible powder, an emulsifiable concentrate or granules. Moreover it can be in a auitable form Eor direct application or as a concentrate or primary composition which requires dilution with water or other diluent before application.
An aqueous concentrate comprises the active ingredients in water-soluble salk form in concentrated aqueous solution which can be diluted with further quantities of water to give 2 solution of suitable concentration for dlrect use.
As a dispersion, the composition comprises the active ingredients dispersed in a liquid medium, preferably water. The primary compostion for a dispersion can ~e provided in a number of forms. For example ;it can be a dispersible solution which comprises the active ingredients dissolved in a water-miscible solvent with the addition of a dispersing agent or it can ~e a dispersible powder comprising the active ingredients and a dispersing agent. A further alternative comprises the active ingredients in the form of a finely ground powder in association wi~h a dispersing agent and intimately mixed with water to gi~e a paste or cream which can if desired be added to an emulsion of oil in water to give a dispersion of active ingredient i~ an aqueous oil emu~sion.
~n emulsioncomprises the active ingredients dissolved in

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' . ' ' . ' ' ' ' ' ' ' , a water-immiscible solvent whlch is formed into an emulsion with water in the presence o~ an e~ulsifying agent. An emulsion of the desired concentration can ~e formed ~rom a primary composition of the follow~ng types: a concentrated stock-emulsion comprising the active ingredients in combination with an emulsifying agent, water and water-immiscîble solvent, or an emulsifiable concentrate comprising a solution of the active ingredients in a water-~mmisciE)le solvent containing an emulsifying agent.
A granular solid comprises t~e active ingredients with or without a solid diluent and prefera~ly in the form of micro-granules.
- The total concentration of the active ingredients, expressed in terms of the free acids, in a composition of the invention intended for direct application to the crop is preferably within the range of 0.02 to 10 per cent by weight, especially 0.05 to 1 per cent by weight. In a primary composition the total amount of active ingredients can vary widely and can be, for example, from 5 to 95 percent by weight of the composition.
Also included in the invention is a method for controlling mayweeds and polygonaceous weeas which comprises applying to the weed~ or their habitat a herbicidal composition comprising ; 4-chloro-2-oxo~enzothiazolin-3~ylacetic acid or a salt or ester thereof and 3,6-dichloro-2-picoli~ic acid or a salt or ester thereo~, A ~articular em~odlment of the invention is a method

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for the selective post-emergence control of mayweeds and polygonaceous weeds in a crop areal which comprises applying to the crop area a herbicidal composition as defined above at an application rate sufficient to control the weeds but substan~
tially non-ph~totoxic to t~e crop.
As stated above the her~icidal composition of the invention can be used for treating a wide range of crops încluding cereals, ~rassicas, pasture and flax. When treating a brassica crop, for example oilseed rape, a preferred method comprises applying a herbicidal composition comprising an alkyl ester of 4-chloro-2-oxobenzothiazolin-3-ylacetia acid, the alkyl ester group conta;ning 1 to 4 carbon atoms and being preferably ethyl, and 3,6-dichloro-2-picolinic ac-~d or a salt or ester thereof.
The composition of the invent;on is applied after the emergence of the weeds and the rate of application of the active ingredients in the composition r expressed in terms of the combined quantit~ of the two a~tive ingredients (as free acid) can be in the range of from 0.1 to 2 kilograms per hectare, more especially from Q.2 to l kilogram per hectare. Preferably the rate of application is such that the quantity of the active ingredient, 3,6-dichloro-2-picolinic acid is between 20 and 125 gms. per hectare, for example between 40 and 120 gms. per hectare.
As is ~ell known the appl'cation rate will be influenced by factors such as the species of weeds present, the stata of growth of the weeds and en~iro~mental conditions. In the case .. - . - - . .
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of cereal crops the composition is best applied prior to jointing and with brassica crops treatment occurs before the appearance o~ flower buds~
The following examples il~ustrate the invention.

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field of spring wheat at a growth stage between the five leaf stage and the commencement of ~oint~ng and heavily infested with Polygonum ~ersicaria at the young plant stage was divided into rectangular replicate areas. The replicate areas were sprayed at various application rates, using a logarithmic sprayer, with aqueous solutions, the quantities of the actîve ingredients being expressed in terms of the free acid 4-chloro-2-oxobenzothiazolin-3-ylacetic acid (X) and the free acid 3,6-dichloro-2-picolinic acid ~Y~ and various mixtures of them.
Five weeks later the degree of control of the weeds was assessed on an arithmetic scale of 0 to 10 (0 represents no effect; 10 represents 100 per cent kill~ in comparison with control areas which had received no ahemical treatment. The control areas exhibited a heavy and flourishing growth of weeds.
The results given are the average o~ values obtained for each replicate. On the above arithmetic scale of 0-10, a value of 7 or above represents a commer~ially acceptable degree of control.

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,~3 Ac-tive ,~ctive Ingredie-nt Ingredie~t Mixture X Y(~xr~y ~
1. Rate (gm per hectare~ 420 25 420 -~ 25 Degree of control (~-lQ scale) 6.2 0 8.5 2. Rate 420 12.5 420 ~ 12.5 Degree of control ~.2 0 8 3. Rate 210 lQ0 210 ~ 100 Degree of control 3~2 5 9.5 4. Rate 21~ 25 210 + 25 Degree of control 3.2 0 8 5. Rate 140 1~0 140 ~ 100 Degree of control 1.8 5 8 The above results show that the active ingredients gave an enhanced her~icidal effect wh~n used together in a mixture and this effect was evidence of s~nergism.
EX~PLE 2 A ~ield of sprin~-so~n oileed rape at the 5 to 7 leaf stage infested ~ith Ma~tricaria recut~ta at the young plant stage was d;vided into rectangular areas and the areas sprayed at various application rates ~ith aqueous solutions, the quantities being expressed in terms of the free acid 4-chloro-2-oxobenzo-thiasolin-3-~lacetic acid ~ethy~ ester form) ~XJ and the free acid 3,6-dichloro-2-picolin~c acid (~1 and various mixtures of .

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. - -~ . . . . :: ~ - -them, as described in Example 1. ~n as~essment was made seven weeks later, with the ~ollow~ny results.

~ct~ve ~cti~e Ingredient Ingred~ent Mixture x ~r~x-~Y ) 1. Rate (:gm per hectare~560 25 560 ~ 25 Degree of control ~0-10 scale) 3~5 2.5 8.25 2. Rate 56~ 36 560 ~ 36 Degree o~ control 3.5 2.5 10 3. Rate 56~ 50 560 ~ 50 Degree of control 3.5 5 9.5 These results further illustrate the synergistic effect of compositions according to the invention.

A field of winter w~eat infested with mayweeds, Matricaria recutita and Tri~leuro-s~ maritum ssp. ino;dorum at the seedling to young plant stage ~as dividea into replicate plots which were sprayed at various application rates with a~ueous solutions of the active ingredients used separately and togéther as a mixture. The spray was applied at a rate of 344 litres per hectare and the quantities of the active ingredients are Pxpressed below in terms of the free acid 4-chloro-2-oxobenzothiazolin-3-~lacetic acid (potassium salt form) ~X) and in terms of the ~ree acid 3,6-dichloro-2-picolinic acid ' :

' ' , ~ ~ ' ' ' ' : ~ '' - ' ` - ', - - - , : : ... , : , . :, ~: ., . : -i~L~ 3 (monoethanolamine salt ~orm~ (Y~. ~pra~iny was carried out when the wheat was at the fully tillered staye of growth. Nine weeks later the deyree of weed control was assessed on a scale of O to la as descri~ed in Example 1. The results yiven are the averaye of values obtained for eac~ replicate.

Active Active Inyredient Ingredient Mixture X ~ ~X-~Y ) 1. Rate ~gm per hectare~ 100 30 100 ~ 30 Dègree of control ~0-1~ scale~ 4.3 2.7 8.8 2. Rate 70 3a 70 + 30 Degree of control- 2.3 2.7 8.0 The compositions of the invention ~X~Y) were also observed to give excellent conkrol of other hroad-lèaf weeks including Stellaria media.
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A further trial ~as carried out on a autumn-sown oilseed rape crop infested with mayweeds, ~atriaaria recutita and Trip_eurosper _ maritimum- ssp. inodorum at the cotyledon ko young plant stage. The field was divided into replicate plots which were sprayed at various appl;cation rates with aqueous solutions of the active ingredients used separately and together as a mixture. In this instance the oilseed rape was treated at the 3 to ~ leaf stage and an assessment of weed control was made 3-1/2 months later with the following results. X is the active ; - 12 -.~
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~f~ 3 ing:redient 4-chloro-2-oxo~enzothia~,olin-3-~lacetic acid (ethyl ester form) expressed in kerms of the ~ree ~cid and Y ~ the active ~ngredient 3,6-d~chloro~2-picol~n~c acid ~monoethanol-amine salt form) expressed in terms of the ~ree acid.
~ssessment was on a scale o~ 0 to la as descri~ed in Example 1 and the results quoted are an average of values obtained for each repl~cate.

.~ct~ve Active ~ngred~Qnt Ingredient Mixture y (X~Y) 1. Rate ~gm per hectare~3~a 25 300 ~ 25 Degree of control ; (0-10 scale) 1. a 1 . 3 7.7 2. Rate 3aO 50 300 ~ 50 Degree of control1.0 5.2 9.0 3. Rate 40a 25 400 + 25 : Degree of control1.0 1.3 8.8 :~ 4. Rate 4ao 50 400 ~ 50 Degree of control1. a 5.2 9.3 ; S. Rate 500 25 500 + 2S
Degree of control2.3 1.3 9.0 6. Rate 500 50 500 ~ 50 Degree of control2.3 5.2 9.8 ' 7. Rate 600 25 600 ~ 25 Degree of control3.0 1.3 9.6 ~', ~ ~ 13 - :

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8. Rate 600 50 600 ~ 50 Degree of control 3.0 5.2 10.0

9. Rate 7a~ 25 700 + 25 Degree of control 3.3 1.~ 9.8 lQ. Rate 7~0 50 700 ~ 50 Degree of control 3.3 5.2 10.0 The compositions of the invention (X~Y~ also gave excellent control of other broad-leaf weeds including St~l media and Capsella ~ursa-pastoris.
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A dispersible pow~er was prepared by grinding together a ; mixture of the ~ollowing ingredients in a hammer mill.
% w/w Active ingredient 4-chloro-2-o~obenzothiazolin-3-ylacetic acid (ethyl ester form~ e~pressed in terms of the free acid 23.0 Active ingredient as free acid 3,6-dichloro-2-picolinic acid 2.0 20 Dyapol PT* ~Trade Mark~ 10.0 Sodium dioct~lsulphosuccinate 0.5 : Diammonium phospha~e 1.4 Colloidal silicic acid 10.0 :~ Kaolin to 100.0 :25 * A sulphonated condensate of urea, cresol and ~ormaldehyde.
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1.1 lb. 4-chloro-2-oxobenzothiazolin-3-ylace-tic acid was mixed with Q.l lb. 3,6-dichloro-2-picolinic acid and neutralised to pH 7 with d~ethanolamine. Water was added to make an aqueous concentrat~ correspond;`ng to a 20 per cent /v solution of active ingredients ~ased on the free acids. A small amount of wetter, Ethylan PB ('rrade Markl, was added correspond-ing to 0.5 per cent W~v.
Similar a~ueous concentrates ~ere also prepared in which ~oth active ingredients were, respectively, in the potassium salt and in the monoet~anolamine salt form.

An emulsifiable concentrate was prepared by mixing the following ingredients % w~w Active ingr2dient 4-chloro-2-o~o~enzothlazolin-3-ylacetic acid ~ethyl ester forml expressed in terms of the free acid 15.0 Active ingredient as free acid 3,6-dichloro-2-picolinic acid 2.5 Wettol EMl* (Trade Mark~ 3.2 20 Wettol EM3~ ~Trade Mark~ 4.8 Cyclohe~anone 30 0 Xylene to 100.0 * A calcium alkylarylsulphonate emu~sifier.
+ An ethoxylated alkylated vegeta~le oil emulsifier.
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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A herbicidal composition comprising 4-chloro-2 oxobenzothiazolin-3-ylacetic acid or a salt or ester thereof and 3,6-dichloro-2-picolinic acid or a salt or ester thereof, the ratio by weight of the ingredients being from 25:1 to 1:1, expressed in terms of the free acids.

2. A herbicidal composition according to claim 1 which comprises an alkyl ester of 4-chloro-2-oxobenzothiazolin-3-ylacetic acid and 3,6-dichloro-2-picolinic acid or salt or ester thereof.

3. A herbicidal composition according to claim 2 in which the alkyl ester is the ethyl ester.

4. A method for controlling mayweeds or polygonaceous weeds which comprises applying to the weeds or their habitat a herbicidal composition according to claim 2 or claim 3 at an application rate sufficient to control said weeds.

5. A method for the selective post-emergence control of mayweeds or polygonaceous weeds in a crop area comprising applying to the crop area a herbicidal composition according to claim 2 or claim 3 at an application rate sufficient to control the weeds but substantially non-phytotoxic to the crop.

6. A method for the selective post-emergence control of mayweeds or polygonaceous weeds in an oilseed rape crop which comprises applying to the crop area a herbicidal composition according to claim 2 or claim 3 at an application rate sufficient to control the weeds but substantially non-phytotoxic to the crop.

7. A herbicidal composition which comprises a synergistic mixture of active ingredients (a) and (b); ingredient (a) being 3,5-dichloropicolinic acid or a salt or an ester thereof and ingredient (b) being 4-chloro-2-oxobenzothiazolin-3-ylacetic acid or a salt or an ester thereof, wherein the active ingredients (a) and (b) are present in a weight ratio, based on the acid equivalents t of from 1:2 to 1:10.

8. A composition as claimed in claim 1 which comprises the active ingredients in admixture with an next carrier and/or a surface active agent, wherein the active ingredients constitute from 0.02 to 95 percent by weight of the total composition.

9. A method of controlling mayweeds or polygonaceous weeds which comprises applying to the weeds or their habitat a herbicidal composition according to claim 1 r claim 7 or claim 8 at an application rate sufficient to control said weeds.

10. A method for the selective post-emergence control of mayweeds or polygonaceous weeds in a crop area comprising applying to the crop area a herbicidal composition according to either claim 1, claim 7 or claim 8 at an application rate sufficient to control the weeds but substantially non-phytotoxic to the crop.