AU2021102098A4 - Method for preparation of glyphosate composition - Google Patents

Abstract

A method of preparing glyphosate solution in a spray tank, comprising adding ammonium sulfate to spray-water in the spray tank; adding glyphosate acid powder to spray-water in the spray tank; adding a wetter surfactant to spray-water in the spray tank.

Description

Method for Preparation of Glyphosate Composition Field

[001] This invention relates to a method of preparing aqueous glyphosate compositions in a spray tank from relatively water insoluble glyphosate acid powder and to a method of controlling weeds by application of the aqueous glyphosate composition.

Background

[002] Glyphosate in the form of its salts, as opposed to glyphosate in its acid form (N-phosphonomethylglycine), is the most common form of glyphosate that is used as an active agent in agriculture and industrial herbicidal liquid formulations (soluble liquids) or solid formulations (soluble powders or water dispersible granules). Glyphosate salts have been preferred because of glyphosate acid's relative lack of solubility in water. Thus, glyphosate salts have been chosen as the form to use in the vast majority of herbicidal applications because they can be readily dissolved in water by farmers in a spray tank shortly before spray application to plants to be controlled.

[003] The glyphosate salt compositions are generally sold in liquid formulations composed of glyphosate in a salt form and suitable adjuvants, such as surfactant, which may enhance the absorption of the active agent in the plants to be controlled. The content of the active salt is generally expressed in terms of the glyphosate acid equivalent, that is, the equivalent acid content. This allows the activity of different salt compositions to be compared based on the glyphosate component. Typical loadings of commercial salt solution concentrates contain from 20 to 600 g/L glyphosate acid equivalent. The salt forms commonly contain glyphosate with amines or other cations. The amines and cations include isopropylamine, monoethanolamine and potassium in in the case of liquid formulations (soluble liquids). Glyphosate is also sold in the form of water dispersible granule (WDG) formulations which contain the water-soluble glyphosate salt and adjuvants such as solid carriers and wetters which allow the granule and water-soluble salts to be rapidly dissolved in a spray tank by the farmer. The farmer will generally mix the aqueous concentrate or WDG with water in a tank shortly before spray application to the weeds or the area of land on which weeds are to be controlled.

[004] The formulation of glyphosate salt aqueous concentrates and WDGs is carried out by manufacturers in industrial plant facilities and requires sophisticated handling of strong bases such as amines and metal hydroxides many of which are have the potential to cause serious injury from skin or eye contact, inhalation or ignition. Formulation of spray tank compositions from glyphosate acid powder (in the absence of a proton acceptor) has not generally been contemplated. Inappropriate handling of the glyphosate acid and other chemicals not only risks injury but can lead to inaccurate dosing of the active if the glyphosate acid is not fully dissolved. Ineffective formulating can lead to precipitation or settling of glyphosate leading to underdosing or blockage of spray equipment.

[005] Glyphosate acid has poor water solubility which produces fine precipitates in water, particularly at low temperature or in hard water which can lead to blocking of spray nozzles with the risk of ineffective weed control from under dosing of weeds. While in pure water glyphosate has a solubility of about 12 g/L at 200 C the solubility is significantly reduced at lower temperature and/or in even moderately hard water commonly available in farming districts.

[006] Although glyphosate is normally formulated in the form of a water-soluble salt, the herbicide is converted to the acid form in the plant to provide herbicidal activity. Amine salts, on the other hand, are generally water-soluble but often have an unpleasant odour. Furthermore, some amines used in forming salts have a low flash point and present significant process hazards for storage of these amines and preparation of the salts.

[007] AU 2010330690 teaches the inclusion of glyphosate acid with an agriculturally acceptable glyphosate salt in a solid glyphosate formulation such as a granule. The glyphosate acid and the glyphosate salt are in admixture and the mole ratio of glyphosate acid to total glyphosate moieties is at least 10% and less than %.

[008] AU 2007260586 teaches a method of preparing a spray tank mix of glyphosate which involves forming a dilute mixture of a first pack containing a mixture of an alkaline composition together with a surfactant, particularly ethanolamine which is added first to the spray tank and a second pack of glyphosate acid, subsequently added to the spray tank to form a glyphosate salt in situ. The handling of alkaline materials is required. Also, the need to use a pack containing a mixture of the alkaline material and surfactant means farmers cannot benefit from reductions in the price of formulation ingredients and they cannot choose alternative ingredients to suit the conditions due to the need to use a package comprising the strongly alkaline material.

[009] There is a need for a method of preparing an aqueous glyphosate acid tank mix from glyphosate acid in powder form, which is typically the form in which glyphosate is manufactured, and which allows glyphosate acid to be delivered in the acid form without prior formulation of the glyphosate acid with surfactant adjuvants or alkaline materials. It is also desirable for end users such as farmers to have the flexibility to use different adjuvants in an on-farm method and use combinations of the glyphosate acid with different herbicides if desired. It is also desirable to provide tank mixes of (i) glyphosate acid from glyphosate acid in powder form and (ii) other pesticides such as one or more herbicides, insecticides and fungicides so that the tank mix provides a broader spectrum of pest control.

[0010] The discussion of documents, acts, materials, devices, articles and the like is included in this specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters formed part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

Summary of Invention

[0011] We have now found that glyphosate acid spray solution maybe prepared in the spray tank by combining glyphosate acid powder and ammonium sulfate in the spray-water.

[0012] There is provided a method of preparing a glyphosate solution in a spray tank, comprising: adding ammonium sulfate to spray-water in the spray tank; adding glyphosate acid powder to spray-water in the spray tank containing the ammonium sulfate; adding a wetter surfactant to spray-water in the spray tank.

[0013] The glyphosate powder is added to the spray tank following addition of at least a portion of the ammonium sulfate. Addition of the glyphosate powder following the ammonium sulfate addition provides significant advantages in enhancing the dissolution of glyphosate acid and reducing the occurrence of solid precipitates and crystallisation.

[0014] In one embodiment the method comprises a first step of partially filling the spray tank with spray-water, and a subsequent step of filling the partially filled spray tank with spray-water to make up the required spray-water volume following the addition of ammonium sulfate, glyphosate acid, wetter, and any further herbicide or adjuvant.

[0015] In one set of embodiments the method comprises:

adding an initial amount of water to the spray tank; adding ammonium sulfate to the spray tank, optionally in an aqueous mixture; adding an aqueous slurry of glyphosate powder to the spray tank following addition of at least a portion of the ammonium sulfate, preferably all the ammonium sulfate; adding a wetter to the spray tank; optionally adding further water to make up the desired spray volume following addition of the ammonium sulfate glyphosate acid slurry and wetter; and optionally adding a further pesticide during the method.

[0016] In one set of embodiments the wetter surfactant is added to the spray-water following addition of at least a portion of the glyphosate acid and preferably following addition of the glyphosate acid.

Detailed Description

[0017] The invention involves a method of formulating an aqueous composition of glyphosate acid in a spray tank using ammonium sulfate. The ammonium sulfate is typically added to water in the spray tank and may be added in finely divided form such as a powder, granules or as an aqueous mixture. The ammonium sulfate may be pre-dissolved in the water or may be in the form of a slurry in which the ammonium sulfate may be partly dissolved. It is typically convenient to use ammonium sulfate in the form of a powder or granules which are forms readily available for suppliers for a range of agrochemical uses. The ammonium sulfate may be formed into a solution or slurry prior to addition to the spray-water or if desired may be added to the spray water in the form of powder or granules to form the solution of ammonium sulfate. The ammonium sulfate in one embodiment is in crystalline form for example as a powder or granules containing crystalline ammonium sulfate.

[0018] There invention provides an efficient method for the on-farm formulation of aqueous glyphosate acid solution in spray-water. The method involves the addition to spray-water of powdered glyphosate acid technical material and low-cost, safe and commonly available agricultural adjuvants can be individually purchased by the farmer. In the method of the invention, these adjuvants include agricultural ammonium sulfate and agricultural non-ionic wetters. The addition of the ammonium sulfate to the spray-water prior to powdered glyphosate acid provides an unexpected level of stability under conditions of hard water and low temperatures which allowing farmers the flexibility to formulate aqueous glyphosate acid composition directly from powdered glyphosate available from manufacturers without the additional costs associated with pre-formulated proprietary glyphosate compositions.

[0019] We have also observed that the aqueous solution compositions prepared according to the invention show enhanced efficacy (per unit weight (wt) of glyphosate acid equivalent) against important weeds such as ryegrass, capeweed, melons and provide enhanced early brown-out.

[0020] The composition of the ammonium sulfate may comprise at least 70wt% ammonium sulfate, preferably at least 80 wt% ammonium sulfate, more preferably at least 90wt% ammonium sulfate, such as at least 95 wt% ammonium sulfate. Where present other materials may, for example be inert fillers, granulation agents or other materials used in granulation or preserving reducing caking of ammonium sulfate.

[0021] The ammonium sulfate acts as a week acid. It was surprising to find that the use of ammonium sulfate in place of an alkaline material would provide a spray solution containing a solutions of the ammonium sulfate and glyphosate having an acid pH of, for example 2 to 3.5 such as 2.5 to 3. The low pH of 2 to 3.5 such as 2.5 to 3 of the final glyphosate solution allows alkaline materials to be completely omitted and the glyphosate to remain in free acid form from addition to the spray water to the final glyphosate acid solution.

[0022] The glyphosate acid is generally in powder form and typically is of particle size of maximum dimensions of no more than 1 mm preferably no more than 0.5 mm such as 0.01 to 0.5 mm.

[0023] The glyphosate powder will typically contain glyphosate acid and optionally an inert carrier although powders of technical grade glyphosate acid are preferred due to their economical pricing.

[0024] The reference to glyphosate acid herein is the glyphosate free acid and will be understood to be clearly distinguished from glyphosate salts used in solutions or granules of prior art solid and liquid compositions of glyphosate.

[0025] The glyphosate acid powder is typically free of alkali and is relatively insoluble in typical spray-water. The glyphosate acid powder will typically contain at least 90

% by weight glyphosate acid on the dry weight of the powder such as at least 95% by weight. Technical grade glyphosate acid available from manufacturers is typically about 95 wt% to 97 wt% purity.

[0026] In a preferred embodiment the glyphosate acid powder is added to the spray tank as a slurry of the powder. The slurry of powder may be prepared by turbulent mixing in an induction hopper which may also be referred to in the art as an induction vessel for transfer of chemicals to the sprayer.

[0027] An induction hopper may be used which provides mixing of the glyphosate acid powder with water in a swirling flow such as a vortex action. It is particularly preferred that at least the glyphosate acid powder is added via formation of a slurry of the powder in an induction hopper. In a further embodiment the ammonium sulfate and glyphosate acid powder are each added via the chemical induction hopper either simultaneously or preferable the ammonium sulfate is added at least in part prior to addition of the glyphosate acid powder. Induction hoppers known in the art are a smaller tank than the spray tank providing a swirling flow such as a vortex of water within the induction hopper for mixing water with the concentrated material. In the present invention particularly the glyphosate acid and optionally one or both ammonium sulfate and wetter are added to the spray tank after mixing with water in an induction hopper. The induction hopper is adapted to deliver the aqueous mixtures formed in the hopper into the spray tank. It may be placed above the spray tank or may be adapted to transfer the contents of the hopper to the spray tank via a transfer conduit. Suitable induction hoppers for providing swirl (e.g. vortex) mixing are available from Hardi Industries under the trade mark "Granni Pot" or from Gold Acres of St Arnaud, Victoria, Australia.

[0028] In one embodiment the preparation and spraying of the glyphosate composition in accordance with the invention is conducted using spray apparatus comprising a chemical induction hopper adapted to deliver chemicals mixed with water to a spray tank and one or more boom spray arms comprising spray nozzles, the spray tank being adapted to deliver an aqueous composition in the spray tank to the spray nozzles.

[0029] In one embodiment the aqueous composition in the spray tank is continuously agitated in the time period during addition of the ammonium sulfate, glyphosate acid powder, wetter and any other materials and preferably through addition of the water used to make up the final volume of the spray mixture.

[0030] The final spray mixture volume in the spray tank may in one set of embodiments be from 1000 L to 15,000L, preferably about 5,000L.

[0031] In one embodiment the invention further comprises spray application of the glyphosate composition from the spray tank to an area of land in which growth of undesirable plants is to be controlled.

[0032] The rate at which the spray-water is applied to an area of land in which weeds are to be controlled will depend on the concentration of the glyphosate, the presence of any other herbicides and the chosen wetter surfactant. In some embodiments the spray-water may be applied to an area at a rate of at least 20 L/ha, preferably at least

L/ha, more preferably at least 40 L/ha such as at least 50 L/ha, at least 60 L/ha or at least 70 L/ha. The spray-water may be applied to an area at a rate of no more than 400L/ha, preferably no more than 300 L/ha such as no more than 200 L/ha or no more than 100 L/ha.

[0033] The rate of application of spray-water onto an area of land on which plants are to be controlled by the herbicidal composition is preferably 30 L/ha to 200 L/ha, more preferably 40 L/ha to 100 L/ha, preferably about 60 L/ha to 80 L/ha.

[0034] In one embodiment, the quantity of ammonium sulfate added to the spray tank is 0.3 kg/1OOL to 5 kg/1OOL, preferably 0.5 kg/1OOL to 5 kg/1OOL of spray-water, preferably 1 kg/1OOL to 3 kg/1OOL of spray-water, more preferably about 2kg/1OOL of spray-water. Preferably an amount of ammonium sulfate in this range is added to the spray water prior to addition of the glyphosate acid powder.

[0035] The quantity of glyphosate acid powder added to the spray-water is preferably from 1 g/L to 20 g/L spray-water, preferably about 5g/L spray-water (based on final spray-water volume).

[0036] The concentration of ammonium sulfate in the final spray-water composition is typically at least 0.3 wt% such as at least 0.5 wt%, at least 1 wt%, at least 1.5 wt% or at least 2 wt%. Typically, the amount of ammonium sulfate in the final spray-water composition is no more than 6 wt%, preferably no more than 5 wt%, such as no more than 4 wt%, no more than 3 wt% or no more than 2 wt% The concentration of glyphosate in the final spray-water volume is preferably 0.3 wt% to 3 wt% of the spray-water composition. Thus, typically addition to the spray water of ammonium sulfate prior to addition of glyphosate acid is at least 0.3 wt% such as at least 0.5 wt%, at least 1 wt%, at least 1.5 wt% or at least 2 wt%. Typically, the amount of ammonium sulfate added to the spray water spray-water prior to glyphosate acid is no more than 6 wt%, preferably no more than 5 wt%, such as no more than 4 wt%, no more than 3 wt% or no more than 2 wt% wherein the amounts are based on the final solution composition.

[0037] The concentration of glyphosate in the final spray-water volume is preferably 0.3 wt% to 3.

[0038] The quantity of glyphosate acid powder added to the spray tank is typically sufficient to provide an application rate of 0.1 kg/ha-2 kg/ha, preferably about 0.5kg/ha. The glyphosate may be introduced to the spray tank in the form of an aqueous slurry which can be prepared in an induction hopper such as those described herein. The induction hopper will typically provide mixing of the glyphosate acid powder and water in a swirling action.

[0039] The concentration of glyphosate and the application rate in g/ha will depend on whether the composition is used in crop-topping weed control or general control of weeds such as fallow or pre-seed treatment. In the case of general weed control the concentration and rate may be determined having regard to the type and age of weed and the rate required for effective control. In the case crop-topping the concentration of glyphosate is typically in the range of 1.8 g/L to 3.0 g/L such as about 2.4 g/L. In the case of weed control the concentration is typically 4.0 g/L to 10 g/L and preferably g/L to 8 g/L. In terms of grams/hectare the crop-topping rate is typically 80 g/ha to 180 g/ha. For general weed control in fallow or pre-seed weed control the rate is typically 300 g/ha to 1000 g/ha.

[0040] The glyphosate may be transferred to the spray tank from a bag containing, for example 10 kg or 15 kg of glyphosate, by pouring the glyphosate from the bag into an induction hopper, which may be fitted onto the spray tank opening, so as to form a slurry of the glyphosate powder prior to addition to the spray tank. The amount of glyphosate may be measured using a chute attachment fitted to a bulker bag to measure weighed amounts of glyphosate which may be delivered into a container, such as a suitable bag for containing for example 10 kg or 15 kg of glyphosate.

[0041] It is particularly preferred that the wetter is in the form of a liquid composition at 200 C. The liquid composition may, and preferably will, comprise a high concentration of the wetter surfactant such as at least 600g/L preferably 800 g/L of wetter surfactant, more preferably at least 900 g/L wetter surfactant and still more preferably at least 1000 g/L of wetter surfactant.

[0042] The wetter surfactant is itself preferably in the form of a liquid at 200C or a low melting point solid. Low melting point solids may, and preferably will, be presented as liquid formulations. It is particularly preferred that the wetter surfactant is a liquid at 0C. This allows convenient handling of the wetter surfactant by farmers who are more accustomed to dealing with liquid compositions of wetters and the high concentration of liquid wetter surfactant allows storage and handling of this component to be conveniently managed.

[0043] The wetter surfactant is present preferably present in the final spray-water composition in an amount of at least 0.05 wt% preferably at least 0.1 wt%. The wetter surfactant is typically present in the final spray-water composition in an amount of no more than 2 wt%, preferably no more than 1.5 wt%, more preferably no more than 1 wt% and still more preferably no more than 0.5 wt% of the final spray-water.

[0044] The wetter components may comprise a surfactant chosen from the group consisting of alkylaryl ethoxylates, alkyl ethoxylates, amidoaliphaticbetaines, alkylamine alkoxylates particularly fatty amine ethoxylates such as tallowamine ethoxylates, cocobetaine, alkoxylated aliphaticamines, alkylpolyglucosides, alkylglycosides, aliphatic amines, quaternary amines, aliphatic acetates, ethylene diamine ethoxylates, amphoteric surfactants such as polyoxyethylene aliphatic amine oxides and polyoxyethylene aliphatic ether salts, amine oxides and amphoacetates. The term aliphatic is used to include saturated as well as unsaturated hydrocarbon chains and includes linear and branched chains. Glyphosate-synergising surfactants typically contain at least one aliphatic group containing 8 to 22, more frequently 12 to 18 carbon atoms. Discussions of glyphosate-synergising surfactants are provided in US 6207617, WO 95/16351, US Pub 20030158042, US Pub 20050170965 and US Pub 20040224846 the contents of which are herein incorporated by reference. The preferred surfactants are selected from aliphatic, betaines amidoaliphaticbetaines and tallow amine ethoxylates.

[0045] Preferred surfactant include alcohol ethoxylates, alkylarylethoxylates, fatty amine ethoxylates, organosilicones and mixtures of alcohol ethoxylates and alkylarylethoxylates. Suitable agriculturally acceptable surfactants are available from these classes. In one embodiment the wetter added to the spray tank comprises a nonionic wetter, more preferably comprises at least one wetter chosen from alkylphenol ethoxylates, such as octyl phenyl ethoxylates and nonyl phenol ethoxylates, and alcohol ethoxylates, more preferably the wetter surfactant comprises both a nonylphenol ethoxylate and an alcohol ethoxylate. One specific example of a suitable wetter is "Wetter 1000" available from FMC Australia which contains 1000 g/L nonyl phenol and alcohol ethoxylates.

[0046] The method may be conducted at ambient temperature where the temperature. Preferably the method is conducted using water at a temperature of at least 50C preferably at least 100C, more preferably at least 150C and most preferably at least 20C. Unlike processes used in commercial manufacture of glyphosate for farm use the components generally are not heated. Accordingly, the temperature of the water is generally not more than 400C and may be not more than 350C such as not more than 300C or not more than 250C. Water may be heated by running it through black polymer (e.g. polyethylene) pipe or other means such as solar heating or direct conductive heating.

[0047] The glyphosate solution prepared according to the method may be used in method of the invention may be used in spay application to plants to control plant growth such as in the preparation of fallow land, pre-sowing preparation of land and crop-topping. "Crop-topping" is the application of a non-selective herbicide (in this case glyphosate) prior to crop harvest when the target weed is at flowering/early grain fill. The selectivity of the crop-topping process is dependent on a sufficient gap in physiological maturity between crop and weed. Crop-topping is particularly useful in control of weeds in pulse crops.

[0048] Accordingly, in embodiment there is provided a method as described herein further comprising spray application of the glyphosate solution onto an area of land in which the growth of undesirable plants is to be controlled.

[0049] In one set of embodiments the spray application is used in preparation of fallow land or pre-so land preparation. In a further set of embodiments, the spray application of the glyphosate solution is carried out over a plant crop to provide crop topping.

[0050] The method for preparation of the glyphosate acid solution may include addition of a co-pesticides, such as herbicide, fungicides and insecticides, such as one or more herbicides or insecticides registered for pest control in croplands and pastures. The co-pesticide may be added at any stage during the method such as after the mixing of the ammonium sulfate and glyphosate acid. The co-pesticide may, for example, be added in the form of a water-soluble salt, a solution of a water-soluble salt or emulsifiable concentrate of an ester. The co-pesticide component when used is added to the spray tank at some time before completing the addition of spray-water. The co-pesticide may be an acid, acid-salt or ester functional pesticide such as chosen from the aromatic acid herbicides and their salts and esters.

[0051] The relevant herbicides may include:

benzoic acid herbicides such as cambendichlor, chloramben, dicamba, 2,3,6-TBA and tricamba; pyrimidinyloxybenzoic acid herbicides such as bispyribac and pyriminobac; pyrimidinylthiobenzoic acid herbicides such as pyrithiobac; picolinic acid herbicides such as aminopyralid, clopyralid, florpyrauxifen halauxifen and picloram; quinolinecarboxylic acid herbicides such as quinclorac; phenoxyacetic herbicides such as clacyfos, 4-CPA, 2,4-D, 3,4-DA, MCPA and 2,4,5-T; phenoxybutyric herbicides such as 4-CPB2, 4-DB, 3,4-DB, MCPB and 2,4,5-TB; phenoxypropionic herbicides such as cloprop, 4-CPP, dichlorprop, dichlorprop-P, 3,4-DP, fenoprop, mecoprop and mecoprop-P; and quinmerac.

[0052] The additional herbicide may be in the form of an ester or salt.

[0053] The additional pesticide when present may be selected from the group consisting of dicamba, aminopyralid, clopyralid, picloram, quinclorac, 2,4-D ester, MCPA, dichlorprop, dichlorprop-P, mecoprop and mecoprop-P herbicides. Preferred herbicides and insecticides for inclusion as co-pesticides may be selected from the group consisting of cypermethrin pendimethalin, oxyfluorfen, trifluralin, diuron, metolachlor, chlorpyrifos, simazine and atrazine.

[0054] In some embodiments of the invention the aqueous glyphosate acid composition during preparation in accordance with the invention is tank mixed with c co-pesticide liquid composition. Examples of co-pesticides which may be tank mixed in liquid form include trifluralin, s-metolachlor, prosulfocarb, 2,4-D isobutylester, carfentrazone and oxyfluorfen. Some specific examples of these compositions are commercially available as Trifluralin 480, s-metolachlor 960, prosulfocarb 800, 2,4-D IBE 800 (isobutyl ester), carfentrazone 240 and oxyfluorfen 240. The number following the pesticide name generally refers to the concentration of the active in grams per litre of liquid composition. The co-pesticide is preferably in the form of a suspension concentrate, solution concentrate or emulsifiable concentrate.

[0055] The 2,4-D ester co-herbicide may be added in a formulation in an amount of at least 40% on a weight/volume (w/v) of the 2,4-D ester herbicide (based on acid equivalent), preferably more than 60% w/v, more preferably about 62.5% w/v.

[0056] The term "spray-water" refers to the water used in formulating aqueous pesticidal compositions for spray application in control of pests especially pesticidal formulations, which are in a diute form to provide a sprayable preparation, for example, a pressure pack ("aerosol") or commercial scale mobile boom sprayer, for domestic, horticultural or agricultural use. The concentration of materials in the spray water refers to the final spray water volume which may, in accordance with the described process be made up to the final volume following addition of the materials such as ammonium sulfate, glyphosate acid, wetter and optionally additional pesticide.

[0057] The terms "acid equivalent", "a.e." and "gly acid equiv." are used to compare the active glyphosate forms such as between different salts or between salts with glyphosate acid with reference to the equivalent amount of glyphosate acid.

[0058] The term "ha" is used as an abbreviation of hectare and g/ha and kg/ha refer to grams per hectare and kilograms per hectare respectively.

[0059] Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereof.

[0060] The invention will now be described with reference to examples which are provided for the purpose of further understanding embodiments of the invention but are not intended to limit the scope or applicability of the invention to the specific examples.

EXAMPLES

[0061] Example 1

[0062] Spray-water was run into a 5000L spray tank on a boom spray rig. The water was passed through a chemical induction hopper mounted on the spray rig, and the passage of water in the chemical induction hopper caused the water in the hopper to swirl.

[0063] As the spray tank was filling up, ammonium sulfate was added to the swirling water stream in the chemical hopper (at a rate of 2kg per 100L of final spray-water volume).

[0064] After addition of the ammonium sulfate, glyphosate acid technical material (95% to 97% purity) was added to the swirling water stream in the chemical hopper (at a rate of 0.5kg per 1OOL of final spray-water volume).

[0065] After addition of the glyphosate acid technical material, Wetter 1000 (comprising 100g/L of nonylphenol ethoxylates and alcohol ethoxylates) was added to the swirling water stream in the chemical hopper (at a rate of 250 ml wetter concentrate per 100 L spray-water.

[0066] Example 2 (tendency of glyphosate acid to precipitate))

[0067] This example shows that the propensity of glyphosate acid to crystallise at low temperature in water of low hardness (tap water) is decreased if increasing levels of ammonium sulfate (AMS) are added to the water before the addition of glyphosate acid.

[0068] Materials • Glyphosate acid technical powder 97% active (Gly-97) • Ammonium sulfate small granules (AMS) • Wetter 1000 (WA) • Tap water of low hardness

[0069] Protocol • Solutions of AMS were made by adding 1% and 2% AMS to low-hardness tap water. • 0.5% glyphosate acid (Gly-97) was added to the AMS solution at 20 deg C

. • 0.25% Wetter 1000 was added to all liquors • Solubility (of Gly-97) at 20 deg C was assessed in both liquors. • Propensity of Gly-97 to crystallise after 3 hrs at 6 deg C was assessed in both liquors.

[0070] Results • Both liquors were clear and free from crystals at 20 deg C. • The liquor made with 1% AMS and 0.5% gly-97 was assessed as being at high risk of precipitation at low temperature. • The liquor made with 2% AMS and 0.5% gly-97 was assessed as being at low risk of precipitation at low temperature.

[0071] Example 3 (solubilisation of glyphosate acid in aqueous solution of ammonium sulfate)

[0072] This example shows that the capacity of an aqueous solution to solubilise glyphosate acid increases significantly as increasing amounts of AMS are introduced into the aqueous solution.

[0073] Materials • Glyphosate acid technical powder 97% active (Gly-97) • Ammonium sulfate small granules (AMS) • Tap water of low hardness

[0074] Protocol • Solutions of 0%, 1%, 2% and 7% AMS were prepared in low-hardness tap water. • Varying quantities of Gly-97 were added to the above solutions with stirring at 18 deg C. • The capacity of the solutions to solubilise various quantities of Gly-97 was assessed, based on the quantity dissolved within 15 mins of addition to a stirred liquor.

[0075] Results • At 0% added AMS, 8g/L of Gly-97 was soluble in low-hardness tap water, however at 8.5 g/L Gly-97 and above some Gly-97 remained undissolved. • At 1% added AMS, 8.9g/L Gly-97 was soluble in low-hardness tap water. • At 2% added AMS, 11.1 g/L Gly =97 was soluble in low-hardness tap water. • At 7% added AMS, 15.9 g/L Gly-97 was soluble in low-hardness tap water.

[0076] Example 4. Bioefficacy of glyphosate acid in AMS solution)

[0077] The following treatments shown in Table 1 were applied to control ryegrass weeds (late tillering stage) and Capeweed (6-leaf rosette stage).

[0078] Table 1

Treatment Treatment Treatment rate (per number hectare)

T1 Untreated control (UTC) T2 First add 1% AMS to spray-water in spray tank, 464 g Gly-97 then add finely divided Gly-97 T3 First add 1% AMS to spray-water in spray tank, 464 g Gly-97, 120 ml Wetter then add finely divided Gly-97, then add 1000 Wetter 1000 T4 First add 1% AMS to spray-water in spray tank, 1 L then add Glyphosate 450 specialty liquid Glyphosate formulation T5 First add 1% AMS to spray-water in spray tank, 957 ml then add Glyphosate 470 (specialty liquid Glyphosate formulation

Note: T3 is a composition in accordance with the invention.

[0079] Application protocol (post-emergent).

[0080] The application equipment was a handheld 2m boom, the nozzle size was 110-015, the nozzle type was "Agrotop" Flat fan air induction, spray water application rate 60 L/ha, spraying pressure 230 kPa.

[0081] Assessment Timings (day after application =DA) • 7 DA • 12 DA * 21 DA

[0082] Assessment Protocol (weed brownout)

[0083] Brownout score was based on visual assessment of weed phytotoxicity (0 100% scale, where 0 = no damage and 100 = total weed death.) Results of the assessment are shown in Table 2 below.

[0084] Table 2

% rating Effects Non-evident Negligible: slight discoloration, distorting and/or stunting barely seen Slight: discoloration, distortion and/or stunting clearly seen Moderate damage: moderate discoloration, marked distortion and/or stunting, recovery expected Substantial damage, much discoloration, distortion and/or stunting. Some damage irreversible. 50 Majority of plants damaged, many irreversibly, some necrosis, discoloration and severe distortions 60 Nearly all plants damaged, most irreversibly, some plants killed (<40%), substantial necrosis and distortion 70 Severe; substantial number of plants killed (40-60%), much necrosis and distortion 80 Very severe: majority of plants killed (60-80%), remainder show much necrosis and wilting 90 Remaining live plants (<20%) mostly discoloured and distorted permanently or desiccated 100 Complete loss of plants.

[0085] Statistical Analysis

[0086] Data was recorded in "Agriculture Research Manager" software program and statistically analysed using an analysis of variance with mean values summarised and separated using Least Significant Test at 5% level of probability. Statistical analysis is shown in Table 3 below.

[0087] Table 3

Treatment no Brownout, 7 DA Brownout, 12 DA Brownout, 22 DA

T1 0.00 c 0.00 d 0.00 c

T2 23.33 b 78.67 d 90.00 b

T3 26.67 ab 91.00 a 99.67 a

T4 21.67 b 86.67 b 98.67 a

T5 28.33 ab 86.00 b 100.00 a

Note: In Table 3 values reported with different letter are statistically significantly different.

[0088] Discussion

[0089] At 12 days after application, weed brownout using T3 (the method of the invention) was significantly greater than for other treatments. The achievement of more rapid brown-out is a significant benefit in terms of improved farmer satisfaction with the new method of use of glyphosate.

[0090] Example 5 (Gly-97 solubility in hard water)

[0091] 2% AMS was added to hard water (CaCO3 270 mg/ml, TDS 598 ppm) and the maximum amount of Gly-97 that could be dissolved was measured at a range of temperatures and the results are reported in Table 4 below.

[0092] Table 4

Temperature deg C Max conc sol Gly-97 Gly acid equiv g/L Solution pH in g/L

7.96 7.72 3.0

10 10.58 10.26 2.9

15 12.50 12.13 2.8

20 13.08 12.69 2.7

25 15.12 14.67 2.6

30 17.58 17.05 2.5

35 19.66 19.07 2.5

[0093] Example 6 (Gly conc preferred range)

[0094] It was established that if 2% AMS is dissolved in spray-water, a concentration of Gly-97 of up to 1.2% (preferably up to 1%) was viable to enable spray application under a range of spraying conditions and spray-water compositions.

[0095] Example 7 (examples of spray tank water preparation according to the invention) 1. Half fill total required volume of water into spray tank and maintain full agitation throughout filling 2. Add 2% AMS (based on the full required volume) 3. Add spray pH adjuster if required (e.g. citric acid) 4. Add Gly-97 slowly though an induction hopper as tank is filled to about 75% total required spray-water volume. Minimise dust from powder handling by opening bag corner to pour out powder close to liquid surface in hopper and if necessary, engage overhead spray in induction hopper. 5. Add other tank mix products and then fill spray tank to total required water volume. 6. Add surfactant at 0.2% of tank mix volume (e.g. 4Farmers Wetter 1000 = 1OOOg/L non-ionic alcohol ethoxylate).

[0096] Example 8. Spray-water preparations according to the invention.

[0097] Table 5

Spray- Spray- Spray-water mixing sequence Agricultural use water water (after AMS 2% has been code rate prepared) - does not include (L/ha) water addition steps

SWC1 50 (i) 120 g/ha Gly-97, (ii) 0.2% Spray top barley grass after head Wetter 1000 emergence SWC2 75 (i) 564 g/ha Gly-97, (ii)80 ml Pre-seeding control of emerged and alpha cypermethrin 250 SC, (iii) pre-emerged weeds. Emerged 0.25% Wetter 1000 (250 weeds targeted include Barley grass, ml/lOOL), (iv) 300 ml/ha 24D Annual Ryegrass, Brome grass, Capeweed, Long fruited turnip, ester 680 EC, (v) 1.6 L/ha Indian hedge mustard, Soursob, Pendimethalin 330 EC, Sand fescue, volunteer cereals, medics and wild oats SWC2a 75 As for SWC2 but 24D ester replaced with 100 ml/ha Oxyfluorfen SWC3 75 i)564g/ha Gly-97, (ii)80 ml alpha AsforSWC2 cypermethrin 250 SC, (iii) 0.25% Wetter 1000 (250 ml/lOOL), (iv) 300 ml/ha 24D ester 680 EC, (v) 1.1 L/ha Trifluralin 480 EC SWC4 75 As for SWC3 but 24D ester replaced As for SWC2 with 100 ml/ha oxyfluorfen SWC5 80 (i) 500 g/ha Gly-97, (ii)500 gm/ha Pre-seeding control of emerged weeds diuron 900 DF, (iii)0.2% wetter and pre-emergent weed control. (200ml/100L), (iv)1.0 L/ha Emerged weeds targeted were Annual metalochlor 720 EC, (v)100 ml/ha ryegrass, Wild oats, Bromegrass, Sand oxyfluorfen 240 EC Fescue, Capeweed, Wild geranium (Storks bill -Erodium sp, Salvation Jane, Wild raddish, Sub Clover. SWC6 70 (i) 500 g/L Gly-97, (ii) 750 glha As for SWC5 Simazine 900 WG, (iii) 250 g/ha Atrazine 900 WG, (iv)0,2% Wetter 1000 (v) 100 ml/ha Oxyfluorfen 240 EC, (v) 140 ml/ha Chlorpyrifos 500 EC SWC 7 80 (i) 500 g/ha Gly-97, (ii) 0.2% Wetter Pre-seeding control of emerged weeds 1000, (iii) 2.0 L/ha Trifluralin 480 EC, and pre-emergent weed control. (iv)100 ml/ha Oxyfluorfen 240 EC, Emerged weeds targeted were Annual (v)140 ml/ha Chlorpyrifos 500 EC ryegrass, Wild oats, Bromegrass, Sand Fescue, Capeweed, Wild geranium (Storks bill -Erodium sp. SWC 8 80 (i) 600 g/ha Gly Gly-97, (ii) 0.2% As for SWC 7 Wetter 1000, (iii)100 ml/ha Oxyfluorfen SWC 80 (i) 650, 700, 750 and 800 g/L Gly-97, As for SWC 7 8a,b,c,d otherwise as for SWC 8 SWC 9 90 (i) 650g/ha Gly-97, (ii) 0.2% Wetter As for SWC 7 1000, (iii) 100ml/ha Oxyfluorfen 240 EC, (iv)1.5 L/ha Prosulfocarb 800 EC, (v) 1.5 L/ha Trifluralin 480 EC SWC 10 90 (i) 700 g/ha Gly-97, (ii) 0.2% Wetter As for SWC 7 1000, (iii) 100ml/ha Oxyfluorfen, (iv)2.0 L/ha Trifluralin 480 EC SWC 90 (i) 800 g/ha otherwise as for SWC As for SWC 7 a 10 SWC 11 90 (i) 10OOg/ha Gly-97, (ii) 5g/ha Pre-seeding control of emerged weeds Metsulfuron methyl 600 WG, (iii) and pre-emergent weed control. 0.2% Wetter 1000 (200ml/100L), Emerged weeds targeted were: Annual ryegrass, Wild oats, Bromegrass, Sand

(iv)100 ml/ha Oxyfluorfen 240 EC, Fescue, Capeweed, Wild geranium (v)2.0 L/ha Trifluralin 480 EC (Storks bill -Erodium sp,, Sorrel, Wild Radish, Couch Grass. SWC 12 90 (i) 800 g/ha Gly-97, (ii)500 g/ha Pre-seeding control of emerged weeds Diuron 900 WG, (iii)200 g/ha and pre-emergent weed control. Metribuzin 750 WG, (iv)0.2% Emerged weeds targeted were Annual Wetter 1000 (200ml/100L), (v)100 ryegrass, Wild oats, Bromegrass, Sand ml/ha Oxyfluorfen 240 EC, (vi) 1.5 Fescue, Capeweed, Wild geranium L/ha Trifluralin 480 EC (Storks bill -Erodium sp.

[0098] Example 9

[0099] Agronomic Observations Associated with the use of Spray-water Preparations of Example 8

[00100] Table 6

Spray-water Observation code SWC1 Worked well and reduced viable seed set. Could be seen in the following season by a notable reduction in barley grass plants germinating. SWC2, No compatibility issues, good weed control SWC3 SWC4 Very good weed control. Higher rate of glyphosate used as weeds were older and more established. no compatibility issues SWC 5 Good weed control. No issues with compatibility SWC6 Good weed control. Applied after 8pm in darkness with high humidity no compatibility issues SWC7 Good weed control, no compatibility issues SWC 8 and Good weed control. Higher glyphosate rates used on larger older plants 8 a,b,c later in the season, when temperatures were lower. SWC 9 Good weed control, no compatibility issues SWC 10, Good weed control, no compatibility issues 10a SWC 11 Good weed control, no compatibility issues SWC 12 Good weed control, no compatibility issues

[00101] Note Selection of Wetters

[00102] Commonly available agricultural examples include: • Alcohol ethoxylates • Allkylaryl ethoxylates (including nonylphenol and octylphenol ethoxylates) • Alcohol ethoxylates plus alkylphenols • Fatty amine ethoxylates

• Organosilicones.

[00103] Preferred for this invention are alcohol ethoxylates, alkylaryl ethoxylates and blends thereof. For example, wetters of this type are available under the trade name "Wetter 1000" sold by 4 Farmers, a liquid product which comprises 1000g/L nonylphenol and alcohol ethoxylate blend.

[00104] Process for adding glyphosate acid technical material to a Spray Tank.

[00105] The options include:

[00106] Option A • Place a bulker bag containing glyphosate acid technical material in the field. • Install a chute arrangement (such as a 'Fledbag') to the bulker bag outlet, which enables controlled removal of powder contents, e.g. controlled removal into a bag placed on a set of scales (which enables controlled removal of a given weight). • Unload the contents of the weighed bag into an induction hopper that feeds into the spray tank.

[00107] Option B • Provide glyphosate acid material in 10 or 15 kg bags and unload the bags into the induction hopper that feeds into the induction hopper.

[00108] Option C • Provide Glyphosate acid material in 10 or 15 kg water-soluble bags and place the bag into the spray tank (which has been at least partially filled with spray-water.

[00109] Example 10 - BIOEFFICACY DATA (MELONS)

[00110] The following foliar post-emergent treatments shown in Table 7 were applied to Afghan melons (Citrullus lanatus) weeds. The weed growth stages were Melon Cotyledons - 1 true leaf, Melon vine 2 leaf-reproductive.

[00111]Table 7

Treatment Treatment Treatment rate (per number hectare)

T1 Untreated control (UTC) T2 First add 1% AMS to spray water in spray tank, 368 g Gly-95 technical then add finely divided Gly-95 (95% glyphosate glyphosate = 350g technical powder), then add Wetter 1000 glyphosate acid T3 First add 1% AMS to spray water in spray tank, 737 g Gly-95 technical then add finely divided Gly-95, then add 250 ml glyphosate = 700g Wetter 1000 per 100L of spray water glyphosate acid T4 First add 1% AMS to spray water in spray tank, 400 g Glyphosate 875 then add Glyphosate 875, then add 250 ml (ammonium glyphosate) = Wetter 1000 per 100L of spray water. 350 g glyphosate acid equivalent T5 First add 1% AMS to spray water in spray tank, 800g Glyphosate 875 then add Glyphosate 875, then add 250 ml (ammonium glyphosate) = Wetter 1000 per 100L of spray water. 700 g glyphosate acid equivalent

[00112] Application protocol (post-emergent)

[00113] The application equipment was a handheld 2m boom, the nozzle size was 110-015, the nozzle type was "Agrotop" Flat fan air induction, spray water application rate 100 L/ha, spraying pressure 250 kPa.

[00114] Assessment Timings (day after application =DA) • 6 DA A (day after application) • 10DAA • 19DAA

[00115] Assessment Protocol (weed brownout)

[00116] Brownout score was based on visual assessment of weed phytotoxicity (0-100% scale, where 0 = no damage and 100 = total weed death.) Details are in Table 8 below.

[00117] Table 8

% rating Effects Non-evident 10 Negligible: slight discoloration, distorting and/or stunting barely seen 20 Slight: discoloration, distortion and/or stunting clearly seen 30 Moderate damage: moderate discoloration, marked distortion and/or stunting, recovery expected Substantial damage, much discoloration, distortion and/or stunting. Some damage irreversible. 50 Majority of plants damaged, many irreversibly, some necrosis, discoloration and severe distortions 60 Nearly all plants damaged, most irreversibly, some plants killed (<40%), substantial necrosis and distortion 70 Severe; substantial number of plants killed (40-60%), much necrosis and distortion 80 Very severe: majority of plants killed (60-80%), remainder show much necrosis and wilting 90 Remaining live plants (<20%) mostly discoloured and distorted permanently or desiccated 100 Complete loss of plants.

[00118] Statistical Analysis

[00119] Data was recorded in "Agriculture Research Manager" software program and statistically analysed using an analysis of variance with mean values summarised and separated using Least Significant Test at 5% level of probability. The results are shown in Table 9.

[00120] Table 9

Treatment no. Brownout, melons Brownout, melons, 10DAA 19DAA T1 Od Od T2 57b 62b T3 73a 83a T4 42c 53c T5 63ac 82a

[00121] Note: In the above table values reported with a different letter are statistically significantly different.

[00122] Discussion

[00123] From the above table it can be seen that treatment T2 according to the invention (at 350g/ha glyphosate acid) provided significantly better weed brown-out than treatment T4 (same glyphosate acid equivalent as T2, same ammonium sulfate, same wetter conc.) - the only difference between the two treatments is that glyphosate acid was used in T2 rather than ammonium glyphosate in T4.

[00124] Without wishing to be bound by theory, it is believed that the superior efficacy in T2 arose because glyphosate acid in the spray tank was in acid (rather than neutralised) form.

[00125] Tank-Mix Co-Pesticides

[00126] Compositions in accordance with the invention may be prepared according to T3 of Table 1 with variation to include a further tank-mixed pesticide in the form of a liquid compositions shown in Table 10. The copesticide was added following the AMS and glyphosate acid. The specified co-pesticides in liquid form were found to be compatible when tank-mixed in carrying out the method of the invention. The water used was tap water in Welshpool Western Australia.

[00127] Table 10

Compatibility testing

Test Tank-mixed co-pesticide Second tank mixed co-pesticide

1 Trifluralin 480

2 s-metolachlor 960

3 Trifluralin 480 Prosulfocarb 800

4 Prosulfocarb 800

5 2,4-D IBE 800

6 Carfentrazone 240

7 Oxyfluorfen 240

Claims (29)

Claims

1. A method of preparing aqueous glyphosate solution in a spray tank, comprising adding ammonium sulfate to spray-water in the spray tank; adding glyphosate acid powder to spray-water in the spray tank containing the ammonium sulfate; and adding a wetter surfactant to spray-water in the spray tank.

2. The method of claim 1 wherein the glyphosate acid powder is added to the spray tank following addition of at least a portion of the ammonium sulfate.

3. The method of any one of the previous claims wherein the wetter surfactant is added to the spray tank following the glyphosate acid powder.

4. The method of any one of the previous claims comprising partially filling the spray tank with spray-water, adding the ammonium sulfate, followed by glyphosate acid, wetter, and any further herbicide or adjuvant, and adding spray-water to make up the desired glyphosate solution spray volume.

5. The method of any one of the previous claims wherein the wetter is in the form of a liquid composition at 20 0C comprising at least 600 g/L, preferably at least 800 g/L of surfactant, more preferably at least 900 g/L surfactant and still more preferably at least 1000 g/L surfactant.

6. The method of any one of the previous claims wherein the wetter surfactant is a liquid at 200 C.

7. The method of any one of the previous claims wherein the ammonium sulfate is in the form of granules or powder.

8. The method of any one of the previous claims wherein the ammonium sulfate is crystalline.

9. The method of any one of the previous claims wherein composition of the ammonium sulfate comprises at least 70wt% ammonium sulfate, preferably at least wt% ammonium sulfate, more preferably at least 90wt% ammonium sulfate, such as at least 95 wt% ammonium sulfate.

10. The method of any one of the previous claims, wherein the quantity of ammonium sulfate added to the spray tank is 0.3 kg/1OOL to 5 kg/1OOL of spray water, preferably 0.5 to 5 kg/L such as 1 and 3 kg/100L of volume of spray-water.

11. The method of any one of the previous claims wherein the concentration of glyphosate in the final spray-water volume is 0.2 wt% to 3 wt% of the spray-water composition.

12. The method of any one of the previous claims, wherein the quantity of glyphosate acid powder added to the spray-water is from 1g/L to 20 g/L spray-water, preferably about 5g/L spray-water.

13. The method of any one of the previous claims, wherein the glyphosate acid powder is added to the spray tank as an aqueous slurry.

14. The method of claim 13, wherein the aqueous slurry is prepared in an induction hopper providing mixing of the glyphosate acid powder and water in a swirling action.

15. The method of any one of the previous claims wherein the pH of the aqueous glyphosate acid solution is 2 to 3.5, preferably 2.5 to 3.

16. The method of any one of the previous claims wherein the wetter surfactant is a non-ionic surfactant.

17. The method of any one of the previous claims, wherein the wetter surfactant comprises at least one selected from the group consisting alkylphenol ethoxylates, and alcohol ethoxylates, preferably comprises both a nonylphenol ethoxylate and an alcohol ethoxylate.

18. The method of any one of the previous claims wherein the wetter surfactant is present in the final spray-water composition in an amount of at least 0.05 wt%, preferably at least 0.1 wt%.

19. The method of any one of the previous claims wherein the wetter surfactant is present in the final spray-water composition in an amount of no more than 2 wt%, preferably no more than 1.5 wt%, more preferably no more than 1wt% and still more preferably no more than 0.5wt%

20. The method according to any one of the previous claims further comprising addition of an herbicide or insecticide other than glyphosate to the spray-water.

21. The method of claim 20, wherein the herbicide or insecticide selected from the group consisting of benzoic acid herbicides, pyrimidinyloxybenzoic acid herbicides, picolinic acid herbicides, quinolinecarboxylic acid herbicides, phenoxyacetic herbicides, phenoxybutyric herbicides, phenoxypropionic herbicides anquinmerac. and salts and esters thereof.

22. The method of claim 20, wherein the herbicide or insecticide is selected from the group consisting of cypermethrin pendimethalin, oxyfluorfen, trifluralin, diuron, metolachlor, chlorpyrifos insecticide, simazine and atrazine.

23. The method of any one of the previous claims further comprising spray application of the glyphosate solution onto an area of land in which the growth of undesirable plants is to be controlled.

24. The method of claim 23 wherein the spray-water is applied to an area at least L/ha, preferably at least 30 L/ha, more preferably at least 40 L/ha such as at least L/hq, 60 L/ha or at least 70 L/ha.

25. The method of claim 23 or claim 24 wherein the spray-water is applied to an area at a rate of no more than 400L/ha, preferably no more than 300 L/ha such as no more than 200 L/ha or no more than 100 L/ha.

26. The method of claim 23 to 25 wherein the spray application is used in preparation of fallow land or pre-so land preparation.

27. The method of any one of claims 1 to 26 further comprising spray application of the glyphosate acid solution over a plant crop to provide crop-topping.

28. The method of any one of claims 23 to 27, wherein the aqueous solution is applied to weeds and provides early brown-out of weeds.

29. The method of any one of claims 23 to 28, wherein the aqueous solution is applied to one or more of weeds selected from ryegrass, capeweed and melon weed to provide early brown-out of weeds.