AU2012101324A4 - Herbicidal composition - Google Patents

Abstract

The invention relates to a solid particulate herbicidal composition comprising flupropanate, methods for the preparation of a solid particulate herbicidal composition comprising flupropanate and to methods for controlling weeds by using a solid particulate herbicidal composition comprising flupropanate. The solid particulate herbicidal composition may be readily broadcast in an area of treatment.

Description

P/00/009A Section 29 AUSTRALIA Patents Act 1990 INNOVATION PATENT SPECIFICATION Invention Title: HERBICIDAL COMPOSITION Applicant: Granular Products Pty Ltd The invention is described in the following statement: 1 7019 2 HERBICIDAL COMPOSITION The present application is a divisional application from Australian patent application number 2007202192, entire disclosure of which is incorporated 5 herein by refer rence. FIELD OF THE INVENTION The present invention relates to a solid particulate herbicidal composition comprising flupropanate, methods for the preparation of a solid particulate 10 herbicidal composition comprising flupropanate and to methods for controlling weeds by using a solid particulate herbicidal composition comprising flupropanate. In particular, the present invention relates to granular herbicidal compositions comprising flupropanate. 15 BACKGROUND Flupropanate also known as 2,2,3,3,-tetrafluoropropanoic acid, is an effective herbicide which is generally presented in salt form and is used for the selective control of undesirable perennial grasses in pastures and non-crop applications. The sodium salt form of flupropanate is also known as tetrapion or 20 flupropanate-sodium. Flupropanate-sodium is highly water soluble and many commercially available herbicidal compositions comprising the sodium salt of flupropanate as the active ingredient are formulated as aqueous liquid solutions. An example of a 25 commercial liquid herbicide composition comprising flupropanate is TaskforceTM, an aqueous preparation having a specific gravity of 1.45 and pH 8-10 and containing flupropanate-sodium at a concentration of 745g/litre (acid equivalent basis), which equals 857 g/litre sodium salt basis. 30 While liquid herbicide formulations are convenient, there are a number of problems associated with their use.

3 Aerial sprays are frequently used to deliver liquid flupropanate formulations to a desired treatment area. However, aerial application is problematic due to spray drift and spray capture of the herbicide by off-target foliage. Off-target foliage may comprise woodland having a canopy up to 100 feet up from the 5 ground, or any overhanging or neighboring foliage. Off-target foliage may therefore intercept herbicide spray drops applied aerially under still or windy conditions. As a result, the active herbicide may not reach the targeted foliage. 10 In order to -ninimize spray drift, large drop sizes having a diameter of approximately 250 microns or more are required. Because of the large drop size, relatively large quantities of water need to be applied with the active ingredient to provide adequate cover. This means that a helicopter load of liquid herbicide (limited to a given liquid volume) can only cover a relatively 15 small spray area, resulting in high application costs. In addition, in order to control weeds in wooded country with prolific seed producing capabilities, complete kill of the weeds under the woodland canopy is highly desirable. Many conventional liquid flupropanate formulations are 20 prone to evaporation when applied as spray droplets. As a result, aerial application of a liquid formulation above the tree canopy may result in up to half the spray volume being lost to evaporation and off-target capture. Consequently, there may be up to 50% variation of herbicide application across the treatment area. Furthermore, the control of weeds in undulating 25 and hilly country is made harder due to the problem of having to follow the terrain, resulting in applications being performed at excessive height. The active ingredient of many commercial formulations, flupropanate-sodium, is commonly supplied as a concentrated aqueous solution. Consequently, the 30 preparation of liquid herbicide formulations is relatively easy and economical while the preparation of solid formulations has been difficult to achieve.

4 It would be desirable to provide a convenient, cost effective and easy-to-use solid herbicidal composition comprising flupropanate which can be readily distributed in a desired treatment area and that does not suffer from the above disadvantages. 5 The discussicn 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 matter, formed part of the prior art base or were common general 10 knowledge in the field relevant to the present invention as it existed before the priority date of this application. SUMMARY The present invention relates to a solid particulate herbicidal composition 15 comprising flLpropanate for distributing flupropanate over a treatment area. In one aspect, the present invention provides a solid granular herbicidal composition for broadcasting in an area to be treated with the herbicide flupropanate, the composition comprising granules of size in the range of from 20 0.3 mm to 5 mm comprising a carrier material into which has been absorbed aqueous liquor comprising from 2% to 25% by weight flupropanate-sodium, on an acid equivalent basis, of the weight of the granular herbicidal composition. The composition comprises from about 2 to 25% by weight of flupropanate. 25 Here and he-eafter, unless otherwise specified, flupropanate content will be described in terms of acid equivalent basis. The flupropanate comprises the sodium salt of flupropanate. In a preferred aspect, the ratio of flupropanate to water in the composition is in the range of from about 4:1 to 1:1. 30 The herbicidal composition of the invention may further comprise a carrier material. Preferably, the herbicidal composition comprises a freely flowing carrier material which remains freely flowing when up to 10% of additional water is loaded into the carrier material.

5 In one embodiment of the invention, it is preferred that the carrier material loaded with 7% additional water has a crush strength of at least about 500g. More preferably, the carrier material loaded with 10% additional water has a 5 crush strength of at least about 500g. It is further preferred that the carrier material has a bulk density in the range of from 0.5 to 2 grams per cubic centimeter. It is preferred that the carrier material has a particle size in the range of from 10 about 0.3 - 5 mm. Accordingly, it is preferred that the carrier material preferably is a solid particulate. Further, it is preferred that the carrier material is not an agglomerate of finer particles, but rather derives by crushing clay or other carrier to reduce the particle size to this size range. 15 It is preferred that the carrier material comprises clay, peat or zeolites. Preferably, the clay is selected from the group consisting of bentonite, attapulgite, kaolin, montmorillonite, smectite and hectonite. When the carrier material comprises zeolite, it is preferred that the zeolite is a natural zeolite. When the carrier material comprises peat, it is preferred that the peat is 20 selected from the group consisting of reed-sedge peat, lignin peat, peat moss, sphagnum peat. In a preferred aspect, the carrier material comprises bentonite, peat, smectite or hectorite. In one preference the carrier material comprises a bentonite clay, more preferably a sodium bentonite clay. In another preferred embodiment, the carrier material is attapulgite. 25 A further aspect of the present invention provides a method for the preparation of a solid particulate herbicidal composition comprising flupropanate. In accordance with one aspect, there is provided a method for the preparation 30 of a solid particulate herbicidal composition comprising the step of applying an aqueous solution comprising fluproponate-sodium to a solid particulate carrier material.

6 Yet a further aspect of the invention provides a method of controlling weeds comprising pre-emergent or post-emergent (preferably pre-emergent) application of a solid particulate composition comprising flupropanate to the locus in whi& control is required. 5 As used herein, "flupropanate" includes the acid and salt forms of 2,2,3,3 tetrafluoropropanoic acid. DETAILED DESCRIPTION 10 The present invention relates to a solid particulate herbicidal composition comprising fIL propanate. In one aspect, the present invention provides a solid particulate herbicidal composition comprising flupropanate and water. 15 The herbicidal composition may be in any solid particulate form that can be readily distributed by a user in an area to be treated by the herbicide. The herbicidal composition of the invention is typically a flowable composition. Suitable forms of the composition include but are not limited to powders, 20 flakes, granules, needles and pellets. Preferably, the herbicidal composition is the form of granules, or any other solid form suitable for broadcasting in a desired treatment area. The particulates of the herbicidal composition may be of any suitable size. 25 However, it is preferred that the herbicidal composition comprise particles of a size that is sufficient to enable the composition to be readily broadcast and spread on the ground to provide adequate coverage to a treatment area, and thereafter to remain on the ground and not be susceptible to dusting or movement by wind, air currents and the like. Removal or movement of the 30 composition may be detrimental to other foliage in the vicinity of the area of treatment which is not the intended target of the herbicide. When the composition is in the form of granules, it is preferred that the granules have an 7 average particle size of from about particle size range of from about 0.3 - 5 mm, even more preferably from about 1 - 3 mm. The herbicidal composition of the invention comprises flupropanate as the 5 main active ingredient. Flupropanate is a compound that selectively targets and kills perennial grasses such as serrated tussock. Flupropanate and in particular, thE sodium salt of flupropanate has a high saturation solubility in water. For example, an aqueous solution containing up to 80% (w/v) flupropanate-sodium can be obtained at 20'C 10 Flupropanate can be present in the composition in any herbicidally effective amount. Preferably, the composition comprises from about 2-25%, more preferably from about 2-15% by weight, even more preferably from about 5 10% by weight of flupropanate (acid equivalent basis). The flupropanate 15 active ingredient in the form of the sodium salt of the compound. The herbicidal composition of the invention comprises water. In a preferred aspect of the invention the composition comprises no more than about 20% by weight of water. More preferably, the composition comprises no more than 20 about 15% by weight of water. It is desirable to maintain relatively minor amounts of vater in the herbicidal composition as excessive amounts of water can have detrimental effects in terms of loss of active agent concentration in the solid composition and reduced properties such as granule crush strength. The weight ratio of flupropanate (acid equivalent basis) to water is preferably in 25 the range of "rom about 4:1 to 1:1, more preferably in the range of from about 8:4 to 5:4. In a preferred embodiment, the herbicidal composition of the invention further comprises a carrier material. The carrier material carries the flupropanate 30 active ingredient and assists to add bulk to the composition and provide a solid, flowable and storage-stable form which can be broadcast onto the use territory using readily available application equipment. The carrier material is usually present in a significant excess compared with the quantity of 8 flupropanate. For this reason, it is preferred that inexpensive carrier materials are used. The carrier material may comprise any material suitable for agricultural use 5 that is capable of binding to and absorbing liquids. Examples of suitable carrier materials include but are not limited to peat, clay and zeolites. When clay is used in the carrier material, the clay is preferably selected from the group corsisting of bentonite, attapulgite, kaolin, montmorillonite, smectite 10 and hectonite. In one preference, the carrier comprises bentonite clay, even more preferably, sodium bentonite clay. In another preference, the carrier material is attapulgite. When the carrier material comprises a zeolite, it is preferred that the zeolite is 15 a natural zeolite. When the carrier material comprises peat, it is preferred that the peat is selected from the group consisting of reed-sedge peat, lignin peat, peat moss, sphagnum peat. The peat will in general comprise organic matter. 20 In a preferred aspect, the carrier material comprises bentonite, peat, smectite, or hectorite. For the preparation of the herbicidal composition, it is preferred that the carrier 25 material be a particulate solid. It is preferable that the solid particulate carrier be capable of binding to or absorbing an aqueous liquid. In this way, the carrier material may be loaded with the aqueous liquor. The particle size of the particulate carrier material may be of any size that will achieve the advantages of the invention, although it is preferred that the carrier material have an 30 average particle size in the range of about 0.3 - 5 mm, more preferably 0.5 to 5mm and, evEn more preferably, about 1 - 3 mm.

9 Preferably, the carrier material has the capacity to absorb at least 7% aqueous liquor, more preferably at least 10% aqueous liquor (based on pre-loaded weight) without liquor bleeding or seepage and without clumping of the carrier material. Preferably the carrier material, when loaded with said aqueous liquor 5 retains its integrity after packing, storage and transport in a storage format such as a 20 kg (or larger) cardboard container or cloth sack. It is preferred that the carrier material remains freely flowing even if a quantity of at least 7%, preferably at least 10% aqueous liquor has been loaded onto the material. 10 It is further preferred that the loaded carrier material has a crush strength sufficient for the material to its shape and to withstand the weight of the solid particulate herbicidal composition when it is stored in a container such as a bag, and the weight of other bags stacked on top of the bag. The crush strength is an indication of the force required to compress the material. When 15 the carrier material is loaded with up to 10% liquid, the crush strength of the carrier is preferably at least about 500 grams, more preferably at least about 800 grams. In a preferred embodiment the composition a freely flowing carrier material 20 with an average particle size in the range 0.3 to 5mm, said carrier material having the characteristic that it remains freely flowing when up to 10% of additional water is loaded into and fully absorbed by the carrier material and is further characterized in that the carrier material when loaded with 7% additional water has a crush strength of at least about 500g. 25 In one embodiment the carrier has a bulk density in the range 0.5-2 grams per cubic centimeters, and further characterized in that the carrier is chosen from the set clay, peat, zeolites, bentonite, attapulgite, kaolin, montmorillonite, smectite, hectonite, reed-sedge peat, lignin peat, peat moss, sphagnum peat, 30 sodium bentonite clay, natural zeolites. The carrier material also preferably has a bulk density in the range of from about 0.5 to 2 grams per cubic centimeter, more preferably in the range of 10 about 0.7 to 1.5 grams per cubic centimeter. Such relatively high bulk density values are desirable to ensure that fixed-volume applicator systems (e.g. helicopters or fixed wing aircraft) can cover more territory in a given application run. 5 The herbicidal composition of the invention may optionally include additional formulation ingredients if desired, to aid in the processing, appearance or use of the solid particulate composition. Such further optional ingredients would not adversely affect the activity of the flupropanate and would be readily 10 apparent to the person skilled in the art. Examples of additional formulation ingredients include but are not limited to flow agents, surfactants, disintegration aids, preservatives, colors and the like. The herbicidal composition of the invention may also include other active 15 ingredients such as herbicides or pesticides. The solid particles of the herbicidal composition of the invention are stable upon storage and are readily handled by the user for application. However, upon wetting the particles after their distribution in an application area with 20 moisture (e.g. rain) the solid particles of the composition are able to release the active flupropanate into the treatment area. The release may be due to disruption or disintegration of the solid particles or by some other mechanism. It is preferred that most if not all of the flupropanate is released from the solid particles after contact with rain. 25 Preparation A further aspect of the present invention relates to a method for the preparation of a solid particulate herbicidal composition comprising flupropanate. 20 In one aspect, the present invention provides a method for the preparation of a solid particulate herbicidal composition comprising the step of applying an 11 aqueous solu-ion comprising fluproponate-sodium to a solid particulate carrier material. The flupropariate solution may be obtained from commercial sources or may 5 be prepared by mixing a quantity of flupropanate with a solvent. A suitable solvent is water due to the high water solubility of flupropanate and in particular, flupropanate-sodium. Non-aqueous solvents may also be used. The flupropanate solution may be applied to the carrier material using any 10 method known in the art. A preferred method for applying the fluproponate solution involves mixing the fluproponate solution with the carrier material for a time sufficient to allow the flupropanate to become absorbed by the carrier. A suitable mixing vessel such as a rotating drum or a ribbon mixer may be used. Other methods of applying the fluproponate solution such as by spraying the 15 flupropanate solution onto the carrier material may also be used. The carrier material may be formed as an agglomerate of smaller particles, however, it is preferred that the carrier material comprises particles of size 0.3mm to 5mm and the aqueous solution of flupropanate-sodium is absorbed 20 into unagglomerated particles. It is preferred, however, that the carrier material has a particle size of 0.3 to 5mm. 25 In another embodiment of the invention, the solid particulate herbicidal composition may be prepared by applying a flupropanate solution onto a solid particulate carrier. An advantage of this method that the active ingredient is directly loaded onto the carrier to thereby form the particulate herbicidal composition ii a single step process. The resultant composition consequently 30 does not need to undergo subsequent drying or further processing. When a solid particulate carrier material is used, the particulate carrier may be prepared by any suitable method known in the art in order to achieve the 12 desired particle size range. Suitable methods include for example, crushing or screening larger material to reduce the size to within the range of 0.3mm to 5mm. Screer ing may be used to achieve the desired particle size.. 5 The fluproponate solution that is used in the methods of the invention is preferably a concentrated solution, such that only an aliquot of the concentrated solution is required to be applied to the carrier material to obtain the desired final concentration of the active ingredient. Preferably, the final concentration of flupropanate in the herbicidal composition is in the range of 10 50g/kg to 100 g/kg (acid equivalent basis). If necessary, a diluent may be added during the preparation of the herbicidal composition in order to obtain the desired final concentration of flupropanate. Suitable diluents include for example solvents such as water, or additives that aid in the processing or use of the herbicidal composition. 15 A further aspect of the invention provides a method of controlling weeds using a solid particulate herbicidal composition comprising flupropanate. The method preferably comprises the application of the herbicidal composition to the locus of the weed in which control is required. 20 In use, the hErbicidal composition is broadcast by the user and distributed onto the area to be treated by the herbicide. The composition may be broadcast at any suitable application rate that provides adequate cover to an area of land and achieves the advantages of controlling weed growth. Preferred 25 application rates are from about 0.5 - 3.0 kg flupropanate (acid equivalent basis) per hectare and more preferably from about 0.7 -1.5 kg flupropanate per hectare. Such application rates are known and may be readily ascertained by the person skilled in the art. 30 The herbicidal composition may be broadcast and spread onto the ground surface to be treated with the aid of suitable equipment known for use in spreading so!id particulate materials. Such equipment would be known to the 13 skilled addressee. Examples of suitable broadcasting and spreading equipment are detailed in the Examples. The solid particulate material is spread onto the treatment zone by 5 broadcasting, for example broadcasting from an aircraft such as a helicopter or fixed wing aircraft. The herbicidal composition of the invention once applied, can be readily distributed orIto the treatment surface by water, such as rain, so that the 10 flupropanate active ingredient is then released from the composition into the treatment area. The solid particulate herbicidal composition of the invention advantageously allows easy end controlled distribution of the herbicide to be achieved in the 15 desired area of application. Because of the use of a solid form of the herbicide composition, more consistent application can be achieved with less wastage of the flupropanate active. The solid particulate herbicidal composition of the invention may be used to 20 control the growth and spread of various weeds. The herbicidal composition of the invention is particularly advantageous for controlling the growth of perennial grasses such as giant rats tail grass, parramatta grass, serrated tussock, African lovegrass and Chilean needle grass. 25 The herbicidail composition of the invention is preferably for post-emergent application to weeds.

14 EXAMPLES Example I - Preparation of Flupropanate Granules This example describes the synthesis of granules of a flupropanate 5 composition according to the invention. The granules in this example will be designated as M10, M5, L10 and L5. The designations relate to the following properties: M10: medium size 10% active, M5: medium size, 5% active, LIO: large size, 10% active and L5: large 10 size, 5% active. Preparation cf M10 Granules M10 granules were made by taking Trufeed granular sodium bentonite (Particle size - Dry Screen (retained 5mm) 2%, Dry Screen (passing 1.5mm) 15 5%, Water absorption 750%, Bulk Density 1.0, pH 7), sold by Unimin, Melbourne Australia. The granules were crushed using a rolling crushing mill (Kustner Switzerland Model No. 28888), and passed through a 2 mm sieve. The particles which passed through a 2mm sieve and were retained on a 1 mm sieve were used for further treatment. 20 To check for carrier suitability, sieved particles were loaded with 7% water and 10% water, to check that no water bleeding occurred when the granules were loaded with water, and that the granules remained freely flowing after the absorption of significant quantities of aqueous liquor (these wet samples then 25 discarded). The sieved particles (20 kg batch) were added to a mixing vessel (Minimix 150 Belle Group Sheen UK) and flupropanate concentrate liquor (60% flupropanate, acid equivalent basis) was slowly poured onto the mixing 30 granules over a 10 minute period. Sufficient flupropanate liquor was added to provide a loading of 10% flupropanate (acid equivalent basis) on final granule weight. The riixing was continued for a further 20 minutes after the pouring 15 was complete. A flow agent (precipitated silica, Hisil 257 Femz Corporation) was added until a concentration of 1 -2% of final product weight was achieved. Preparation of M5 Granules 5 M5 granules were following the procedure detailed above for the M10 granules, except that the granules were loaded with 5% flupropanate (acid equivalent bas;is). Preparation of L10 Granules 10 L10 granules were made following the procedure detailed above for the M10 granules, except that particles which passed through a 3mm sieve and were retained on a 2mm sieve were retained for treatment. Preparation of L5 Granules 15 L5 granules were made in the same way as L10 granules, except that the granules werE loaded with 5% flupropanate (acid equivalent basis). None of the granules prepared in this example required drying prior to packing and application. 20 Properties of M1O, M5, L10 and L5 Granules: The packing density and crush strength of the M10, M5, L10, L5 granules respectively are shown in Table 1: 25 Table 1 Granule Packing Density Crush Strength M10 1.02g/kg 500-600g M5 1.01g/kg 550-700g L10 1.05g/kg 500-600g L5 1.03g/kg 550-700g 16 Example 2 -- Aerial application of Liquid Flupropanate Composition (Comparative Example) This example describes the aerial application of flupropanate liquid formulation in Rockhamton, Queensland, Australia. The application aircraft was an Air 5 Tractor 502 (-nade by Air Tractor, USA), and the volume of the hopper was 1800 litres. ~~he hopper was filled with a liquor comprising 1728 parts water and 72 parts flupropanate liquid concentrate (2 litres of concentrate contains 1.49 kg flupropanate , acid equivalent basis). The Air Tractor was used to treat rats tail grass using 50 litres/hectare of spray liquor (i.e. 1.49kg flupropanate 10 per ha application rate, acid equivalent basis). The Air Tractor was equipped with a nozzle arrangement configured for large droplets (VMD 336 micron). The Air Tractor flew at 120 knots during spray application, and the spray was delivered through a flat fan 4020 nozzle oriented at 10 degrees to air flow (zero degrees corresponds to straight backwards orientation). The application 15 pressure was 40 psi, and the application height was 30 metres. The flupropanate spray was applied over open woodland with 15 - 20% canopy cover, and the canopy height varied up to 30 metres. Standard methods (WRK string system with fluorescent marker dye in liquor, water 20 sensitive paper, comparison with application over unwooded area etc) were used to establish that (a) 25% of liquor (volume) discharged from the Air Tractor did not reach the ground because of interception by the canopy, (b) 40% of liquor (volume) discharged from the Air Tractor did not reach the ground because of evaporation, (c) the area covered using the 1800 litre 25 hopper load of application liquor was 36 hectares - this corresponds to an aerial application cost of approx $50 per hectare and (d) the coefficient of variation of liquor reaching the ground across the application area was 35%. Example 3 - Aerial application of MIO Granules 30 This example describes the aerial application of flupropanate granules according to this invention. Granules designated M10 as prepared in Example 1 contained 10% flupropanate (acid equivalent basis) by weight. The 1800 litre hopper cn the Air Tractor 502 was filled with M10 granules, and was fitted 17 at the base with a Transland model meterate precision applicator (Transland Inc, USA). Granules dispensed by the applicator were fed into a Transland model Venturi spreader (Transland Model 23539, 10 vane slimline spreader). The meterate applicator was calibrated to deliver 15 kg of granules per hectare 5 (based on a 120 knot application velocity). This corresponds to an application rate of 1.5 kg flupropanate (acid equivalent basis) per hectare. Other application ccnditions were as per Example 2. Standard methods (including the use of the WRK granular system for granule 10 distribution) were used to establish that (a) less than 5% of the granules were intercepted by the canopy, (b) less than 5% of the granules did not reach the ground for any reason, (c) the area covered using the 1800 litre hopper load of the applicator was 120 hectares - this corresponds to an application cost of $15 per hectare and (d) the coefficient of variation of granules reaching the 15 ground across the application area was 8%. Example 4 - Herbicidal Efficacy This example describes and compares the relative efficacy of granular and liquid formulations of flupropanate on giant rats tail grass devoid of canopy 20 cover. Hand application was used in both cases. The example also describes the relative efficacy for various granules designated M10, M5, L10 and L5, prepared in accordance with Example 1. Materials and Methods 25 The experimental site was located at Kunwarara approximately 70km north of Rockhampton in Central Queensland. The site had been fenced to exclude stock for a number of years. The plots were located on areas of dense giant rats tail grass (Sporobolus pyramidalis) to ensure there were plenty of weed plants to evaluate. There were minimal numbers of other plant species in the 30 plots, therefore herbicide selectivity was not tested.

18 Experimental design The experimEntal design was a randomised block design with 4 blocks, 10 treatments and a square plot size of 5 x 5m. Sampling consisted of running a measuring tape diagonally across the plot. Starting approximately 1.5 m along 5 the tape (-1 m from the sides of the plot) plants were individually located (distance along tape, left or right of tape, distance out from tape). The basal diameter of Icated plants was measured in two directions. Plant basal area was calculated from the diameter measurements using the formula for an oval. Measurements were taken prior to the application of herbicide (15 December 10 2004) and 14 months later (9 February 2006). Approximately 20 plants were individually identified and measured per plot. Ten treatments were combined in the same experimental design, with two groups of treatments available for comparison (Table 2 and 3). 15 The first group of treatments assessed the effect of different herbicide active ingredient application rates using granular formulation M10 (Table 2). The second group of treatments assessed the effect of four different granular 20 formulations (two granule sizes and two herbicide concentrations) at the same herbicide active ingredient application rate (Table 3). Treatment 3 (medium sized granule and 10% herbicide concentration, 100% rate) was common to both treatment groups. All treatments with the granular 25 herbicide composition were compared with weeds treated with liquid herbicide composition (currently available herbicide formulation - 100% recommended rate) and untreated control. All treatments were statistically analysed together.

19 Table 2. AE sessment of the efficacy of varying application rates of flupropanate granular herbicide compared to the recommended liquid formulation rate (100%). The M10 granule was used for all the granule 5 treatments. Treatment Herbicide Rate Granule Number Treatment Name Number (g active per ha) per m 2 1 Granules 50% rate 745 44.7 2 Granules 80% rate 1192 71.5 3 Granules 100% rate 1490 89.4 4 Granules 150% rate 2235 134.1 5 Granules 200% rate 2980 178.8 9 Liquid Control 100% rate 1490 10 Untreated control 0 20 Table 3. Assessment of the efficacy of different flupropanate granule formulations at the same application rate. Two granule sizes and two herbicide concentrations (4 combinations) that modified the granule number per area were tested. All granule treatments and the liquid control were 5 applied at the recommended 100% rate. Treatment Herbicide Rate Granule Number Treatment Name Number (g active per ha) per M2 Granules, Medium 3 size, 10% conc. 1490 89.40 (M10) 6 Granules, Large 1490 119.20 size, 5% conc. (L5) Granules, Large 7 size, 10% conc. 1490 59.60 (L10) 8 Granule, Medium 1490 178.80 size, 5% conc. (M5) 9 Liquid Control 1490 Untreated control 10 0 Herbicide application Each granular herbicide composition was weighed for each plot and mixed 10 with approximately 2.5 L of sand. The mixture was hand-spread across the plot, crossing the plot in two directions. A 'dummy' plot was erected prior to herbicide application to practice hand-spreading the sand. The liquid herbicide was applied with a backpack sprayer and 0.9 m boom. The rate of application was calibratEd by measuring the spray volume required to spray a 'dummy' 15 plot in two directions. Prior to herbicide application, the plots were clearly outlined by running tape along the plot borders.

21 Weather conditions at time of application were hot (38*C) and humid. The 14 months following herbicide application was generally dry for the region. Results and Discussion 5 Treatment Group 1: Efficacy of varying rates of granular flupropanate herbicide compared to liquid flupropanate herbicide Plant death ir creased with flupropanate herbicide application rate. There was 10 no significant difference between the 100% rate granular flupropanate formulation (medium size, 10% concentration) on plant death (73.3%) compared to the liquid flupropanate formulation (79.8%). Increasing the granular herbicide application rate to 150% increased plant death to 92.5%, which suggests the efficacy may be slightly improved at a rate greater than 15 100% rate. Few plants died when no herbicide treatment was applied. There was also no significant difference on the alive basal area remaining after 14 months between the 100% rate granular formulation (5.7%) compared to the liquid formulation (14.3%). 20 Treatment Group 2: Efficacy of different granular flupropanate herbicide formulations There was no significant difference between the different flupropanate granular formulations on plant death and the alive basal area remaining after 14 25 months, however the medium size 10% concentration (M10) formulation and the large size 5% concentration (L5) formulation had the greatest plant death and least alive basal area remaining after 14 months. Impact of different granular flupropanate formulations (using the same 30 active ingredient application rate) on a) Plant death (LSD 5% is 29.1), and b) Alive basal area (LSD 5% is 11.8), 14 months after herbicide application: 22 There appeared to be no consistent link between granule number and plant death, although the treatment with the least granule number (large granule, 10% concentration treatment - 60 granules per M 2 ) had the lowest plant death. 5 In this experiment, there was no significant difference between the granular and the liquid flupropanate herbicide formulations in efficacy for giant rats tail grass (Sporobolus pyramidalis) control when applied at the recommended active ingredient rate (1490 g active per ha). 10 Example 5 - Assessment of Carrier Materials This example describes tests performed on a range of potential carrier materials to establish the suitability of these materials for the preparation of granular flupropanate compositions in accordance with this invention. 15 Test 1 - Water absorption The first test involved stirring the potential carrier granules with a spatula in a beaker with 10% added water (drop-wise water addition to the beaker), and checking that the treated granules remained freely flowing at the end of the treatment. If the potential carrier granules were not freely flowing at the end of 20 this treatment (or if they could not hold the water without seepage, run-off or bleeding), the granules were allocated a failed status, and discarded. Test 2 - Crush strength The second test involved taking granules of the carrier material loaded with 25 10% added water, and subjecting these granules to a crush test. A single granule was placed on a balance and a flat surface was pressed down on the single granule until it collapsed or was significantly distorted. The weight recorded by the balance at collapse was noted (20 replicates performed and results averaged). The potential carrier material was accorded a pass status if 30 the crush wEight was over 500g. The following potential carrier granules were tested for crush strength: Zeolite, calcined flint clay, Doen grey clay, peat, vermiculite, sand, perlite, bentonite. The details of the potential carrier materials are shown in Table 4.

23 Table 4 Compound Brand Packing Density Zeolite Escott Natural Zeolite 1.6 g/mli Calcined Flirt Clay Small Mountain 2.5 g/ml Montmorillonite Doen Grey Clay 1.16g/ml Fibrous Peal Biogreen Fibrous Peat 0.6 - 1.0 g/ml Vermiculite Packing Vermiculite 0.16 g/ml Sand Garfield washed sand 1.4 g/ml Perlite Exfoliators Perlite 0.32 g/ml Bentonite Trufeed Granular bentonite 1.0 g/ml The results of the crush strength tests are as follows: Zeolite (failed), calcined flint clay (failed), Doen grey clay (200 -300 g crush 5 strength - nct a pass), peat (800 - 1000 g crush strength - pass), vermiculite (50 - 100 g crush strength - not a pass), sand (failed), perlite (100 - 250 g crush strength - not a pass), bentonite (500 - 700g crush strength - pass). Example 6 10 This example is based on the use of the carrier granule "Attasorb 8/16 LVM" (low volatile matter) which is a granular heat-treated attapulgite sold by BASF company, and having a chemical composition (Mg,AI)5Si8020.4H20. The product (unloaded granule) bulk density is 561 kg/cubic meter, and the particle specific grave ty is 2.4 (indicative values, subject to some variability). The carrier 15 does not disintegrate in water, and the particle size range is 1.2 - 2.4 mm. 10 kg of carrier granules (Attasorb 8/16 LVM) were placed into the bowl of a cement mixer, and the mixer was set in motion. 1.6 kg flupropanate aqueous solution comprising 857g/L sodium flupropanate (equivalent to 745 g/L 20 flupropanate acid equivalent basis) was slowly poured from a jug into moving mass of carrier granules inside the cement mixer, and mixing was continued for a further 10 minutes after the last of the flupropanate aqueous solution was added. Dur ng this time the granules became dry in appearance and became freely-flowing. At this time and thereafter, the granules were referred to as 24 "fully loaded". No water-removal steps of any kind were carried out, however immediately after loading the granules were referred to as "wet" and 10 minutes after :umbling the loaded granules in the cement mixer, the granules were referred to as "dry". The 10 minute post-loading agitation step was 5 referred to as "drying" because as liquor was more completely absorbed into the carrier granules, the granules came to have a more dry appearance. The following observations were made immediately after loading (ie "wet stage"): (a) speed of absorption of liquid, (b) softness of wet granules, (c) attrition. These observations were repeated for dry granules. 10 Addition of 1.6 kg flupropanate liquor (said liquor at 745 g/L acid-equivalent flupropanate) to 10 kg of carrier granules resulted in a final formulation with 86.9 g/kg flupropanate (acid equivalent basis). The density of the flupropanate aqueous liquor was 1.423 g/L, and this liquor contained 52.35% 15 flupropanate on an acid-equivalent w/w basis. Carrier granu es were loaded with greater amounts of aqueous sodium flupropanate liquor (745 g/l acid-equivalent basis) to see if the granules had the capacity to form robust granular products at higher loading levels. 20 The crush strength of the fully loaded granules was determined as follows: individual loacled granules were compressed on a scale by hand pressure using the blunt end of a rod and the weight at which the granule crushed was recorded. Thirty replicates were taken and the average of the replicates is 25 shown in Table 5 ("loaded crush strength"). The dust content after loading was established by visual means. 200g grams of loaded grarules were placed into a 600 ml glass beaker and stirred with a spoon. The dust content post loading was considered low if less than 10% of 30 the surface of :he base of the beaker was covered in fines after stirring. Fully loaded granules were placed in water to see if full or partial disintegration occurred.

25 The capacity of the fully loaded granules to release active agent (flupropanate sodium) was established by conducting glass house evaluations or field trials with the loaded granules, and confirming that the bio-efficacy was at least 5 substantially equivalent to a sprayed-on liquid formulation carrying the same quantity of active agent per spray area as the granules. The term pH (1%) refers to the pH obtained when 1g of loaded granules were added to 100 mIs water, with mixing for 5 minutes. 10 The bulk density (post loading) was measured by (a) pouring 100g of loaded granules into a measuring cylinder and noting the volume; and (b) lightly tapping the measuring cylinder for 50 times on the work bench (2.5 cm vertical up-and-down tapping motion), followed by a further volume measurement. The first of the above measurements was designated "bulk density pour" and the 15 second was designated "bulk density tap". The results for the granules of Example 6 are displayed in Table 5. Another granule loading process was carried out using the materials and 20 procedures referred to above, with the exception that a greater quantity of flupropanate sodium aqueous liquid (4.17 kg rather than 1.6 kg) was added in the loading steo. Example 7 25 This example is based on the use of the carrier granule "Attapulgite B.G.", sold by Ashapura Industries. The procedures were as for Example 6, and the results for the loaded granules of Example 7 are displayed in Table 5.

26 Example 8 This example is based on the use of the carrier granule "Agrifix 102" an attapulgite granule sold by Hudson marketing. The procedures were as for Example 6 and the results for the loaded granules of Example 8 are displayed in Table 5. Example 9 This example is based on the use of the carrier granule "Agrifix" 103 an attapulgite granule sold by Hudson marketing. The procedures were as for 10 Example 6 except at 1/100 scale (e.g. 1O0g rather than 10kg of granules were used, with a proportionate reduction in other components). Agitation was carried out with a spoon rather than a cement mixer. The results for the loaded granules of Example 9 are displayed in Table 5. 15 Example 10 This example s based on the use of the carrier granule "Arumpo sun/air dried sodium bentoriite", a bentonite granule sold by Arumpo. The procedures were as for Example 6 and the results for the loaded granules of Example 10 are displayed in Table 5. 20 Example 11 This example is based on the use of the carrier granule "Arumpo kiln-dried sodium bentonite", a bentonite granule sold by Arumpo. The procedures were as for Example 9 and the results for the loaded granules of Example 11 are 25 displayed in Table 5. Example 12 This example is based on the use of the carrier granule "Trufeed", a bentonite granule sold by Unimin-Silbelco. The procedures were as for Example 9, and 30 the results for the loaded granules are displayed in Table 5.

27 Example 13 This example is based on the use of the carrier granule "Clay E calcium bentonite, type ED", a bentonite granule sold by Watheroo minerals. The procedures were as for Example 9, and the results for the loaded granules are 5 displayed in Table 5. Commentary on Results The loaded g-anules in Example 6 were practical and useful granules. No treatment to remove liquid (aqueous) component was necessary. A 10 significantly higher loading (4.17 kg rather 1.6 kg of aqueous flupropanate liquor) could be used and the loaded granule had good granule properties. The loaded granules in Example 7 were practical and useful granules. No treatment to remove liquid (aqueous) component was necessary. A somewhat 15 higher loading (2.3 kg rather than 1.6 kg of aqueous flupropanate liquor) could be used and the loaded granule had good granule properties. The loaded granules in Examples 8 and 9 were practical and useful granules. No treatment to remove liquid (aqueous) component was necessary. 20 The loaded granules in Examples 10 and 11 were relatively dusty when compared with Examples 6 - 9. The loaded granules of Example 12 were not practical at standard loading 25 (86.9g flupropanate acid equivalent/kg) because they were too dusty, however, at lower loading (43.5 g flupropanate acid equivalent/kg) the granules were practical and useful. The loaded granules of Example 13 were not practical at standard loading, 30 however they were moderately satisfactory (low to medium level of fines) at half standard loading.

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Claims (5)

1. A solid granular herbicidal composition for broadcasting in an area to be treated with the herbicide flupropanate, the composition comprising granules of size in the range of from 0.3 mm to 5 mm comprising a carrie- material into which has been absorbed aqueous liquor comprising from 2% to 25% by weight flupropanate-sodium, on an acid equivalent basis, of the weight of the granular herbicidal composition.

2. A solid granular herbicidal composition according to claim 1 wherein the granules are of size in the range of from 1 mm to 3 mm, the weight ratio of flupropanate-sodium on an acid equivalent basis to water is in the range of from 4 : 1 to 1 : 1 and the granules comprise no more than 20 % by weight of water.

3. A solid particulate herbicide according to any one of the previous claims where n the granules are non-agglomerated clay and the carrier has a crush strengthh when loaded with 10 % w/w water of over 500 g.

4. A solid particulate herbicide according to any one of the previous claims wherein the carrier material is attapulgite.

5. A method of controlling the growth of perennial grasses on an area of land comprising the step of broadcasting the solid particulate herbicide according to any one of the previous claims from an aircraft onto the area of land having the perennial grasses at an application rate in the range of from 0.5 kg to 3.0 kg flupropanate sodium based on acid equivalent per hectare of land.