AU2699099A - Low volatility formulations of clomazone - Google Patents

Description

RgulaV II 3.2(2 Regulation 3.2(2)

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: LOW VOLATIUTY FORMULATIONS OF CLOMAZONE The following statement Is a full description of this invention, including the best method of performing it known to us LOW VOLATILITY FORMULATIONS OF CLOMAZONE The present invention relates to formulations of clomazone having reduced volatility relative to conventional emulsifiable concentrates of clomazone. In particular it relates to microencapsulated formulations of clomazone in which the clomazone is encapsulated in a shell of polyurea.

Clomazone, the common name for 2-(2-chlorophenyl)methyl- 4 4 dimethyl-3-isoxazolinone, a highly effective herbicide, is also highly volatile, so much so that clomazone applied to the soil in a target area may move to adjacent areas and there cause discoloration, most typically whitening or some degree of bleaching, of a variety of crops, trees, or decorative plants. While this bleaching, indicative of the mode of action of the herbicide, may be temporary when plants are exposed to sufficiently low concentrations, it is unwelcome, even when it does not result in the destruction of the plant.

Accordingly, the label for the use of Command® 4 EC Herbicide, an emulsifiable concentrate formulation in commercial use that contains four pounds of clomazone per gallon of formulation, lists a number of restrictions on how the product is to be used, including weather conditions, spray volume and pressure, and distance from areas where plants are in commercial production. For example, for preemergent applications clomazone is not to be applied within 1,500 feet of commercial fruit, nut, or vegetable production or commercial greenhouses or nurseries. Clearly, this is a severe limitation on the use of an herbicide.

It is the purpose of the present invention to reduce the volatility of clomazone formulations, so that problem of off-site injury is significantly reduced, by at least fifty percent, while maintaining a satisfactory level of herbicidal activity in the target area.

Attempts to prepare formulations of encapsulated clomazone by the general methods known to the art, including polyamide shells as well as polyurea, frequently resulted in formulations that not only gave little or no reduction in volatility, but had poor physical characteristics, undesirable agglomeration of the capsules or separation of phases. Perhaps one factor accounting for the difficulty in preparing satisfactory formulations is the

I

-2significant water solubility of clomazone. No reports of formulations of encapsulated clomazone have been found.

It has now been found that encapsulated formulations of clomazone for which the volatility is reduced to fifty percent or less than that of the commercially available Command® 4 EC emulsifiable concentrate of clomazone, and which retain a satisfactory level of herbicidal activity, can be prepared, provided that the isocyanate and amine moieties that are to form the polyurea shell wall are carefully selected.

The process of the invention involves the following steps: providing an aqueous phase containing an emulsifier, preferably a partially hydrolyzed polyvinyl alcohol; an antifoam agent, and optionally a xanthan gum viscosity modifier/stabilizer; providing a water immiscible phase consisting of clomazone and polymethylene polyphenyl isocyanate, with or without a hydrocarbon solvent; emulsifying the water immiscible phase in the aqueous phase to form a dispersion of water-immiscible droplets throughout the aqueous phase; agitating the dispersion while adding to it, either neat or in aqueous solution, ethylenediamine, diethyltriamine, triethylenetetramine, 1,6-hexanediamine, or a mixture of the polyfunctional amines, thus forming a polyurea shell wall around the water-immiscible droplets. Once the microcapsules are formed, the suspension is cured by moderate heating, after which one or more stabilizing agents, such as propylene glycol, xanthan gum, smectite clay, or an ionic dispersing agent such as a sulfonate of an alkyl napthalene, may be added, as is well-known in the art. It has also been found that adjusting the pH of the formulation from mildly acidic to mildly alkaline conditions, such as a range of from 6.5 to 9.0, pH 8.9, results in a formulation having improved storage stability. The addition of these materials after encapsulation and curing to adjust viscosity and suspensibility is not seen to have any effect on the loss of clomazone through volatility or on the herbicidal efficacy of the formulation.

The aqueous phase will ordinarily contain 0.3 to 3.0, preferably 0.8 to weight percent of one or more emulsifiers, polyvinyl alcohol, 0.05 to 0.20, preferably 0.06 to 0.15, weight percent of the xanthan gum viscosity modifier/stabilizer, if it is used, and 0.1 to 1.0, preferably 0.4 to 0.9, weight percent of the antifoam agent.

-3- The water-immiscible phase will ordinarily consist of 60 to 85, preferably to 77, weight percent of clomazone, an amount of polymethylene polyphenyl isocyanate (PMPPI) such that the ratio of clomazone to PMPPI is in the range of 1:1 to 6:1, preferably 4.5:1 to 4.8:1, and an aromatic hydrocarbon solvent for the two solutes. However, use of solvent is optional in the preparation of formulations containing more than about two pounds of clomazone per gallon of formulation. In such preparations a small amount of solvent may still be used to depress the melting point.

The amine solution will ordinarily contain 10 to 100, preferably 30 to weight percent of ethylenediamine, diethylenetriamine, triethylenetetramine, 1,6-hexanediamine, or preferably a mixture of the polyfunctional amines, with ethylene diamine being used only in a mixture.

The emulsification step requires high shear mixing to give small droplets of the immiscible phase. Factors that influence droplet size, which determines the eventual size of the microcapsules, as well as the stability of the emulsion, include speed and length of mixing, the type and amount of surfactant, solvent, temperature, and viscosity, as well as the xanthan gum, when used.

Selection of the appropriate microcapsule size to achieve the purposes of the invention requires a balance between competing factors. In general, increasing microcapsule size decreases volatility, but also decreases suspensibility of the particles, while decreasing size yields better suspensibility, but higher volatility. For the purposes of the present invention the average size of the microcapsules is 5 to 50 microns, preferably 5 to microns. The operating conditions to yield microcapsules of a desired size will depend on the emulsifying equipment used, and the adjustment to determine the proper conditions is well within the skill of the art.

In contrast to the conditions of the emulsification step, agitation during the amine addition should be gentle. Stirring is continued while the suspension is cured by heating to a temperature of 35 to 60, preferably 45 to 50 for 3 to 10, preferably 4 to 5, hours.

The amounts of post encapsulation additives to be added typically would be selected from one or more of 0.75 to 6.5 wt. propylene glycol, 0.05 to 0.30 wt. xanthan gum, 0.25 to 0.50 wt. smectite clay, and 0.5 to wt. one or more surfactants, each weight percent relative to the weight of the formulation after addition of the stabilizers.

-4- The formulations of the present invention are prepared by the methods exemplified in the following examples.

Example 1 Preparation of a Clomazone 1.5 Pound/Gallon Capsule Suspension (1.5 CS) Formulation (Formulation A) A stock solution of aqueous 20% (weight/weight) partially hydrolyzed polyvinyl alcohol having an average molecular weight of 13,000 to 23,000 (Airvol 203) was prepared by stirring and heating the appropriate amounts of polyvinyl alcohol and water at about 80-90 °C for one hour. The cooled solution was stored for later use.

In a one-liter stainless steel beaker were placed 20.0 grams of the aqueous 20% polyvinyl alcohol solution prepared above, 1.8 grams of 100 of a polydimethyl siloxane antifoam agent (Dow Coming® 1500), 15.0 grams of aqueous 2% xanthan gum (Kelzan® and 400.0 grams of water. After this mixture was mixed for 20 seconds at high speed in a high-shear mixer, a pre-blended solution of 140.0 grams of clomazone, 30.0 grams of polymethylene polyphenyl isocyanate (PMPPI, Mondur MR), and 30.0 grams of petroleum solvent (a -mixture of C9-C15 aromatic, naphthalene-depleted, hydrocarbons, flash-point 95 Aromatic 200 ND) was added, and the mixture was emulsified in the high shear mixer for five minutes. The mixture was then placed in a one-liter jacketed resin flask with the jacket pre-heated to The mixture was stirred at a moderate speed with an air-powered stirrer, and a solution of 19.0 grams of triethylenetetramine (TETA) in 35.0 grams of water was added in one portion. The mixture was then stirred at °C for four hours. After this time, 2.5 grams of a smectite clay containing magnesium aluminum silicate, titanium dioxide, and cristobalite (Veegum® Ultra), and 15.0 grams of aqueous 2% xanthan gum (Kelzan® M) were added to stabilize the formulation. The formulation was then stirred for about one hour and stored for later use.

The formulations described in Tables 1 and 2 were prepared in this manner.

Example 2 Large Scale Preparation of a Clomazone 2.0 Pound/Gallon Capsule Suspension (2.0 CS) Formulation (Formulation E-1) A solution of 5.24 pounds of polyvinyl alcohol (Airvol 203), 2.38 pounds of an aqueous solution of 20% polydimethyl siloxane antifoam agent (Dow Coming® 1520), and 0.21 pound of xanthan gum viscosity modifier/stabilizer (Kelzan® S) in 284.20 pounds of water was placed in a 500 gallon stainless steel vessel, and stirred at 80 °C for one hour. After this time the solution was cooled to 20 °C and placed in an 80 gallon batch homogenizer. With the homogenizer in operation, a pre-blended solution of 161.34 pounds of technical clomazone, 34.75 pounds of polymethylene polyphenyl isocyanate (PMPPI, Mondur@ MR), and 34.75 pounds of petroleum solvent (a mixture of C9-C15 aromatic hydrocarbons, flash-point 95 Aromatic 200) was fed by gravity into the homogenizer during a 15 to 90 second period. The mixture was homogenized for two to three minutes. Upon completion of the homogenization, the mixture was placed in a jacketed reactor with the jacket pre-heated to 50 To the jacketed reactor was added, over a period of seconds, an amine mixture consisting of 10.97 pounds of triethylenetetramine (TETA) and 10.97 pounds of 1,6-hexanediamine (HDA). After the amine addition was completed, the mixture was cured with agitation at 25 °C to 50 °C during a four hour period. At the end of the curing period, 35.70 pounds of propylene glycol and 1.19 pounds of xanthan gum were added to stabilize the formulation. The formulation was then cooled to below 30 °C and stored for later use. It had a viscosity of 1870 cps and a suspensibility of 82 Both formulations described in Tables 3 and 4 were prepared in the manner of Example 2. Formulation A-1 is a larger scale version of Formulation A, and Formulation E-1 is a larger scale version of Formulation E.

Formulation P, a three pound per gallon formulation, the components of which are given in Tables 3 and 4, was prepared by the method of Example 2. In this preparation 0.133 pound of the sodium sulfonated naphthalene condensate was added to the aqueous phase during its preparation. The post encapsulation additives, including the remainder of the sodium sulfonated naphthalene condensate, was added after the curing period at about 35 OC, while the formulation continued to mix and cool to -6ambient temperature. The hydrochloric acid was then added to bring the pH from 10.8 to 8.9.

The currently preferred practice, after the curing step, is to continue stirring the formulation until the temperature reaches about 35 0C, and then to add the hydrochloric acid to bring the pH to about 7.8. The post encapsulation additives, including the remainder of the sodium sulfonated naphthalene condensate, is added, and stirring of the formulation is continued for about 30 minutes to give a homogeneous mixture.

In subsequent preparations of Formulation E by the method of Example 1, certain refinements in the procedure have been found advantageous.

Adjusting the pH of the aqueous solution to 4 reduced the undesirable reaction between PMPPI and water, as did cooling the solution to 8-10 0C.

Preparations have also been carried out with the clomazone solution and the amine solution, as well as the initial aqueous solution, all cooled to 8-10 0C.

However, when there is no solvent in the water-immiscible phase, low temperatures are not used to avoid freezing the clomazone.

Other formulations prepared by the method of Example 1, but differing from the formulations of the invention in the components of either the isocyanate- or amine-containing phase, proved to be unsatisfactory in controlling the volatility of clomazone or in the physical stability of the formulation. The compositions of representative unsatisfactory formulations are given in Table 5. Three of these formulations failed to control the volatility of clomazone adequately, as will be shown below. Formulation O was too viscous (6360 cps).

Formulation L is the same as Formulation A of the present invention, except that the polymethylene polyphenyl isocyanate (PMPPI) was replaced with toluene diisocyanate (TDI). TDI is more reactive in water than PMPPI, which causes undesirable side-reactions leading to foaming in the emulsification step of the preparation of this formulation.

Formulation M was an attempt to copy the formulation used successfully in an effective, four pound/gallon, capsule suspension formulation of an insecticide, substituting clomazone for the insecticide. The microcapsules produced were too small, and here, too, TDI caused foaming problems.

-7- Formulation N is the same as Formulation A of the present invention, except that the xanthan gum viscosity modifier/stabilizer is not used in the emulsification step. Batches of Formulation N prepared in this way gave microcapsules that not only are somewhat small, but are not uniform in size and tend to aggregate. Moreover, the formulation has poor physical stability, resulting in phase separation.

That attaining the desired combination of reduced volatility, physical properties, and efficacy is not achieved simply by following the prior art is shown by two additional preparations. Formulations V and W were prepared by the method of US Patent 4,280,833, Example 8. The composition of these formulations is given in Table 5a. Both formulations separated on standing, forming in the bottom of the container a hard-packed layer, which could be redispersed by shaking. Each gave at least as much release of clomazone as the standard Command® 4 EC Herbicide, when subjected to the laboratory volatility test described below.

The average size of the microcapsules of formulations of the invention, as well as the unsatisfactory formulations, is given in Table 6.

Volatility Studies Laboratory tests for the volatility of capsule suspension (CS) formulations of clomazone were carried out in the following manner. Sufficient unsterilized topsoil to conduct the test was passed twice through a 14-mesh sieve to remove large particles and debris. The fine particles were then removed through a 30-mesh sieve, leaving behind topsoil of intermediatesized particles. This intermediate-sized topsoil, 240 grams, was spread uniformly to a thickness of about one to two millimeters over an area of about 27.9 cm. x 41.3 cm in a tray measuring 32.4 cm x 45.7 x 1.9 cm. The topsoil was then sprayed from an overhead track sprayer calibrated to deliver gallons of water per acre. The spray mix consisted of sufficient clomazone test formulation to provide 0.0712 gm of active ingredient in 20 mL of water.

In this manner the clomazone test formulation was applied to the soil at a rate of 1.0 kg a.i. (active ingredient)/ha. Immediately after treatment, the soil was enclosed in a glass jar, where it remained briefly until used.

-8- For each clomazone test formulation, four 22 mm X 300 mm glass chromatography columns, each containing a coarse sintered glass barrier at the bottom, were connected through their bottom ends to a multi-port air manifold, which delivered equal air pressure simultaneously to a number of columns. In each of the four columns was placed 59 gms of the treated topsoil, which filled about 200 mm of the column length. In the top of each column was then placed a polyurethane foam plug designed to fit inside a 21 to 26 mm diameter tube. As soon after the soil treatment as the columns could be set up, a slow stream of air (0.75-1.00 liter per minute per column) from the multi-port air manifold was passed through the soil in each column, causing the volatilized clomazone to collect on the polyurethane foam plug.

The time between the soil treatment and the start of the air flow was about one hour. The air flow was continued for about 18 hours.

Following the 18 hour collection period, the polyurethane foam plug from each column was placed in a 20 mL plastic syringe. The polyurethane foam plug was thoroughly extracted by drawing 15 mL of methanol into the syringe and through the plug, forcing the methanol extract into a beaker, and repeating the process several times. A 0.04 mL aliquot of the 15 mL sample was diluted with 0.96 mL of methanol and 1.0 mL of water. A 0.1 mL aliquot of this solution was analyzed for clomazone content using an enzyme-linked immunosorbent assay (ELISA), a method reported by R. V. Darger et al. (J.

Agr. and Food Chem., 1991, 39, 813-819). The total clomazone content of the foam plug, expressed in micrograms, of each sample was recorded and compared to the clomazone content of the sample from the standard, Command@ 4 EC Herbicide.

The test results, given in Table 7, show that the CS formulations of the present invention are effective in reducing the amount of clomazone lost by volatility. While all of the formulations listed gave a significant reduction in volatility, the results for Formulations E and F, prepared from mixtures of TETA and HDA, are particularly noteworthy, losing only 8% and respectively, as much clomazone as was lost from the standard 4 EC. The Ib/gal formulations made from the single polyfunctional amines, Formulation B from TETA and Formulation D from HDA, each lost more than twice as much clomazone as did the formulations prepared from mixtures.

Also, Formulations G and H each had less volatility loss than that of either -9- HDA or DETA alone (Formulations D and Accordingly, in the preparation of the formulations of this invention, the use of mixtures of DETA or TETA or both with HDA, particularly in ratios of 3:1 to 1:3, give unexpectedly superior reduction of volatility. Mixtures of TETA and EDA give volatility lower than that of TETA alone. However, it should be noted that Formulation P, a 3 Ib/gal formulation, with DETA alone, gave as much reduction in volatility as Formulations G and H.

The unsatisfactory formulations L, M, and N are clearly far less effective in reducing the volatility of clomazone. The high volatility loss for Formulation L (91% of that lost by the standard clomazone 4.0 EC) suggests that the polymeric walls formed from triethylenetetramine (TETA) and TDI are too permeable, allowing the clomazone to volatilize and the walls formed from PMPPI and TETA or PMPPI in combination with TETA and 1,6-hexanediamine (HDA) are much less permeable, so that clomazone loss from volatility is much reduced. Formulation M, which gives excellent results when the active ingredient is a less water-soluble insecticide, is totally unacceptable for clomazone, giving volatility equal to that of the standard clomazone 4.0 EC.

The difference between Formulations A and N in reducing the loss of clomazone through volatility is particularly surprising, inasmuch as the only difference is the absence of xanthan gum in the aqueous solution prior to encapsulation in Formulation N. The function of xanthan gum seems unpredictable, however, since the only difference between Formulations K and O is the presence of xanthan gum in the aqueous solution prior to encapsulation in K. These two formulations have the same volatility loss, but the viscosity of Formulation K is 3640 cps, while that of O is 6360! No discernible difference has been found between Kelzan® M and Kelzan S xanthan gum in the aqueous phase prior to encapsulation in their effect on the formulations.

Formulations V and W, based on the an earlier patent, were no better than the 4 EC formulation in controlling volatility.

Tests to determine the volatility of clomazone CS formulations in the field relative to that of the standard, Command® 4 EC Herbicide were carried out as follows. One trial on Formulation A-1 was conducted in a field of twoweek old sunflowers, a plant species susceptible to clomazone. Plots were established on a 12 X 14 meter grid. Each plot was prepared by removing the sunflower seedlings and other vegetation from areas about 60 cm in diameter located at the intersections of the grid lines. The grid lines were 12 meters apart in one direction and 14 meters apart in the perpendicular direction. The edge of one replicate was at least 12 meters from the edge of the next replicate, a distance sufficient to prevent interference between replicates.

Over each plot where the soil was exposed was placed a 60 cm diameter, open-ended barrel that was lined with a plastic sleeve fashioned from a trash can liner. Each plot was sprayed with 10-15 mL of an aqueous dispersion containing 0.12 gram of active ingredient. To minimize the drift of clomazone, the spraying was conducted inside the barrel using a hand-held sprayer. Upon completion of each application, the barrel was left in place, and the top was covered for about two to three minutes to allow the spray to settle to the soil surface. The barrel was then removed, leaving each plot open to ambient conditions. There were three to four replicates for each test formulation. To prevent cross-contamination, the plastic sleeve was replaced before applying each new test formulation. The test was evaluated at seven days after treatment by measuring the distance from the center of each plot to, first, the most distant point where discoloration of the sunflowers could be found, then at 450 intervals around the center of the plot. The area of discoloration of the sunflowers was calculated, and the area of the direct treatment was subtracted to provide the area affected by the volatility of clomazone.

A second test on Formulation A-1 was carried out in the same manner in a second field of sunflowers, this time with a 44 cm barrel and on a 14 X 14 meter grid. The total areas affected by clomazone movement from each test site for each test formulation and the standard clomazone 4.0 EC formulation were determined. From these data a percent reduction of area discolored by clomazone as compared to the standard Command@ 4 EC was calculated for each test formulation.

A third test, this time with Formulation P, was a series of tests, carried out in different geographic locations having different environmental and soil conditions. At each location a three acre plot was planted with sunflowers.

The clomazone formulations were applied to a 10' X 10' bare ground plot wheni the sunflowers had reached the 2-6 leaf stage. Prerequisite conditions for application were that the soil be moist, but not saturated, to facilitate volatilization. Evaluations were made 7-10 days after application and 10-14 days after the first significant rainfall event by means of the same general method -11 described for the first test. The areas given are totals for all sites; the percent reduction is an average of those from all sites. The test results, given in Table 8, show that Formulation A-1 reduced by one half the area affected by clomazone compared to Command 4 EC, and Formulation P was significantly more effective in reducing volatility..

Efficacy Studies Seeds of bamyardgrass (Echinochloa crusgalli), giant foxtail (Setaria faben), yellow foxtail (Setaria lutescens), shattercane (Sorghum bicolor), and velvetleaf (Abutilon theophrasf) were planted in a 25 cm x 15 cm x 7.5 cm fiber flat containing topsoil. Each species was planted as a single row in the flat, which contained five rows. There were four replicate flats of plants for each rate of application of test formulation. Stock dispersions of each of the test formulations were prepared by dispersing a sufficient amount of formulation to provide 0.0356 gram of active ingredient in 40 mL of water.

From the stock dispersion 20 mL was removed and serially diluted with 20 mL of water to provide application rates of 0.25, 0.125, 0.0625, 0.0313, 0.0156, and 0.0078 kg. a.i./ha. The dispersions of test formulation for each rate of application were then sprayed onto the surface of the soil by a track-sprayer in a sprayhood. Flats were also sprayed as above with the same rates of the standard Command® 4 EC Herbicide. Untreated controls were also included in each test. Upon completion of the spraying the flats were placed in a greenhouse, where they were maintained for fourteen days. After this time the test was visually evaluated for percent weed control. The percent weed control data for each test formulation and the Command 4 EC Herbicide formulation was subjected to regression analysis to determine the rate of application that would provide 85% weed control (ED 8 5 of each of the weed species. From these data the relative potencies of the test formulations (the relative potency of the Command 4 EC Herbicide is 1.0) were determined by means of the following ratio: Formulation Formulation Relative Potency Command Herbicide The test results shown in Table 9 show relatively poor performance for Formulation E in the greenhouse. As shown below, performance of Formulation E in the field was excellent. The reason for the difference -12between greenhouse and field performance is not understood. However, the greenhouse performance of Formulation P was excellent, as was performance in the field, as shown below." In a field test of the efficacy of Formulation A-1 the test formulations were sprayed onto the surface of the soil (preemergence) at an application rate of 1.0 pound a.i./acre in 12.7 X 30 foot plots planted with cotton and weed seeds. There were four replicate plots for each formulation tested. The test formulation was applied by means of a backpack sprayer, equipped with flat fan spray nozzles, at a delivery volume of 15-20 gallons/acre and at a spray pressure of 28-30 psi. The plots were evaluated for percent weed control at and 30 days after emergence of the plant species in the test. The cotton plants were evaluated for bleaching, stunting, and stand reduction. Test results, given in Table 10, show this CS formulation to be slightly less effective against three of the four test species and essentially equivalent to the 4 EC in effects on cotton. (The similarity in effect on cotton is not unexpected, since this test is the result of direct application and does not involve movement to an adjacent site.) In a field test of Formulation E the test formulations were sprayed onto the surface of the soil (preemergence) at application rates of 0.125, 0.25, and 0.5 pound a.i./acre in 6.7 X 12 foot plots planted with eight different plant species. There were four replicate plots for each formulation tested. The test formulations were applied using a backpack sprayer, equipped with four flat fan spray nozzles, at a delivery volume of 20 gallons/acre and at a spray pressure of 25 psi. The plots were evaluated for percent control 20 days after treatment. The data in Table 11 show that this CS formulation at 0.5 pound active ingredient per acre is giving commercial control, defined as at least to 85 percent control of all species, everywhere the standard is giving commercial control, except for shattercane at 0.5 Ib/A, which falls slightly below the percentage goal for control.

Table 12 reports results of a field test of Formulation P and the 4 EC formulation in which both formulations were applied at 0.88 Ib/A preemergence. It is apparent that in most cases where the 4 EC formulation is giving commercial control, Formulation P is also. Again, the effect of the encapsulated formulation P on cotton is negligible.

-13- Table 13 reports another field test of Formulation P, again applied preemergence, that shows that at 0.5 lb/A the encapsulated formulation is controlling all species except shattercane.

As noted above, the stabilizers added after encapsulation and curing are thought to have no effect on the volatility or the efficacy of the formulation.

They are added to stabilize the formulation and adjust the viscosity. It is prefered that each formulation of this invention have a suspensibility of greater than 70%, a viscosity of 1700 to 3800 cps, and a 100 mesh wet screen analysis of greater than 99.95%.

It is understood that there may be variations from the specific embodiments described herein without departing from the spirit or concept of the present invention as defined in the claims. Included in such variations are mixtures in which the encapsulated clomazone of this invention is part of a mixture with one or more other herbicides, flumeturon or sulfentrazone, whether or not encapsulated.

-14- Table 1 Preparation of Clomazone Capsule Suspension (CS) Formulations (Components and Amounts) Weight (grams) Formulation (Ib/aal) A B C D E F Component Aqueous Solution Water 430.7 493.00 430.70 493.00 493.00 493.00 PVA 4.0 4.58 4.00 4.58 4.58 4.58 Xanthan Gum 0.3 0.35 0.30 0.35 0.35 0.35 Antifoam 1.8 2.06 1.80 2.06 2.00 2.06 Isocyanate Solution Clomazone 140.0 280.00 140.00 280.00 280.00 280.00 Petroleum Solvent 30.0 60.00 30.00 60.00 60.00 60.00 PMPPI 30.0 60.00 30.00 60.00 60.00 60.00 Amine Solution TETA 19.0 38.00 19.00 9.50 HDA 19.00 30.00 19.00 28.50 Water 35.0 62.00 31.00 70.00 62.00 62.00 Post Encapsulation Stabilizers Smectite Clay in Water 14.7 Propylene Glycol 19.60 9.00 18.00 9.00 18.00 Xanthan Gum 0.3 0.40 1.00 2.00 1.00 2.00 PVA Airvol® 203 polyvinyl alcohol.

Xanthan gum Kelzan® M and Kelzan S xathan gums differ in that S has been surface treated to improve ease of dispersion. M was used in all cases except post encapsulation in Formulations A, C, D, F, and H.

Antifoam Dow Coming® 1500 is 100% polydimethyl siloxane. Dow Coming 1520 is a 20% solution; amount shown is active ingredient 1500 was used in Formulations A and C; 1520 in the others.

Petroleum solvent Aromatic 200, a mixture of C 9

-C

1 5 aromatic hydrocarbons, flash point 95 That used in Formulation A was naphthalene depleted.

PMPPI Mondur® MR polymethylene polyphenyl isocyanate.

TETA triethylenetetramline.

HDA 1,6-hexanediamine.

Smectite clay Veegum® Ultra clay consisting of magnesium aluminum silicates with titanium dioxide and cristobalite present.

Table 1 (continued) Preparation of Clomazone Capsule Suspension (CS) Formulations (Components and Amounts) Weight (grams) G H J K Formulation (Ib/qal) Component Aqueous Solution Water

PVA

Xanthan Gum Antifoam Isocyanate Solution Clomazone Petroleum Solvent

PMPPI

Amine Solution

EDA

TETA

DETA

HDA

Water Post Encapsulation Stabilizers Smectite Clay in Water Propylene Glycol Xanthan Gum 493.00 4.6 0.4 2.1 280.0 60.0 60.0 11.20 19.00 69.8 493.00 4.6 0.4 2.06 280.00 60.00 60.00 19.00 19.00 62.00 493.00 4.58 0.35 2.06 280.00 60.00 60.00 493.30 4.58 2.06 280.00 60.00 60.00 7.6 7.6 30.4 30.4 62.00 62.00 493.00 4.58 0.35 2.06 280.00 60.00 60.00 38.00 62.00 19.60 0.40 41.00 19.60 1.00 0.40 19.60 0.40 EDA ethylenediamine.

DETA diethylenetriamine.

-16- Table 2 Clomazone Capsule Suspension (CS) Formulations (Components and Weight/Weight Percents) Percent (wt/v B C(1.5) Formulation (lb/qal) Component Clomazone Encapsulating Polymer

PMPPI

HDA

TETA

Polyvinyl Alcohol Petroleum Solvent Polydimethyl Siloxane- Antifoam Agent Xanthan Gum-Viscosity Modifier/Stabilizer Propylene Gylcol Stabilizer Smectite Clay-Viscosity Modifier Water D E 19.77 4.24 2.68 0.56 4.24 0.25 0.08 27.45 20.09 27.45 27.72 27.45 5.88 3.73 0.45 5.88 0.20 4.31 5.88 2.72 2.94 0.57 4.31 0.26 0.45 5.88 0.20 5.94 1.88 1.88 0.45 5.94 0.20 5.88 2.79 0.93 0.45 5.88 0.20 0.07 0.19 0.23 0.13 0.23 1.92 1.29 1.77 0.89 1.77 0.35 67.83 54.42 66.26 55.20 54.95 54.42 rr U^

Y

Total 100.00 100.00 100.00U 100.00 100.00u I UU.UU -17- Table 2 (continued) Clomazone Capsule Suspension (CS) Formulations (Components and Weight/Weight Percents) Percent (wt/wt) Formulation (Ib/qal) Component Clomazone Encapsulating Polymer

PMPPI

EDA

TETA

DETA

HDA

Polyvinyl Alcohol Petroleum Solvent Polydimethyl Siloxane- Antifoam Agent Xanthan Gum-Viscosity Modifier/Stabilizer Propylene Gylcol Stabilizer Water G H J K 28.00' 26.7 27.45 27.45 27.45 6.00 5.70 1.12 1.80 1.90 1.80 0.46 0.44 6.00 5.70 0.21 0.20 0.04 0.13 5.88 0.75 2.98 0.45 5.88 0.20 5.88 0.75 2.98 0.45 5.88 0.20 5.88 3.73 0.45 5.88 0.20 0.07 0.04 0.07 4.67 1.92 1.92 1.92 56.27 52.86 54.42 54.45 54.42 Total 100.00 100.00 100.00 100.00 100.00 -18- Table 3 Large Scale Preparation of Clomazone CS Formulations (Components and Amounts) Weight (Ibs) Formulation (Ib/gal) A-1 E-1 P Component Aqueous Soultion Water 222.85 284.20 274.4 PVA 2.000 5.24 5.05 Xanthan Gum 0.300 0.21 0.22 Antifoam 0.900 2.38 4.30 Isocyanate Solution Clomazone 70.000 161.34 289.8 Petroleum Solvent 15.000 34.75 31.2 PMPPI 15.000 34.75 62.5 Amine Solution TETA 9.500 10.97 HDA -10.97 DETA 40.0 Water 17.500 40.50 Post Encapsulation Additives Propylene Glycol 35.70 39.8 Xanthan Gum 1.19 26.2* Smectite Clay 1.250 Bactericide A' 0.009 Bactericide B 2 0.177 Bactericide C 3 0.4 Na Naphthalene Sulfonate 4 5.3 Concentrated Aqueous Hcl 22.33 Amphoteric Surfactant 5 26.0 1Dowcide® A (o-phenylphenate tetrahydrate) 2 Legend® MK (mixture of 2-methyl-4-isothiazolin-3-ones) 3 Proxel® (1,2-benzisothiazolin-3-one) 4Sodium salt of sulfonated naphthalene condensate MirataineTM H2C-HA (sodium lauriminodipropionate) as a 1.9 wt% dispersion.

-19- Table 4 Large Scale Clomazone CS Formulations (Components and Weight/Weight Percents) Percent(wt/wt) E-1 Formulation Component Clomazone Encapsulating Polymer

PMPPI

HDA

TETA

DETA

Polyvinyl Alcohol Petroleum Solvent Polydimethyl Siloxane-Antifoam Agent Xanthan Gum-Viscosity Modifier/Stabilizer Propylene Gylcol Stabilizer Smectite Clay-Viscosity Modifier Bactericides Na Naphthalene Sulfonate Condensate Concentrated Aqueous Hcl Amphoteric Surfactant Water 19.74 25.93 35.02 4.23 2.68 0.56 4.23 0.25 0.09 5.59 1.76 1.76 0.84 5.59 0.38 0.23 5.74 7.55 4.83 0.61 3.77 0.53 0.09 4.81 U. 0.05 0.05 0.65 2.70 0.94 67.80 52.18 38.45 Total Total 100.00 100.00 100.0 Table Unsatisfactory Clomazone CS Formulations (Components and Weight/Weight Percents) Formulation Component Clomazone Encapsulating Polymer

PMPPI

TDI

TETA

DETA

EDA

Polyvinyl Alcohol Petroleum Solvent Polydimethyl Siloxane Antifoam Agent Xanthan Gum Viscosity Modifier/Stabilizer Propylene Glycol Stabilizer Water Percent (Wt/Wt) L M N O 20.38 30.43 20.38 27.45 4.37 2.77 0.58 4.37 0.26 0.04 67.23* 1.73 0.73 0.15 2.72 0.28 63.96 4.37 2.77 5.88 3.73 0.58 0.45 4.37 5.88 0.26 0.20 S 0.04 1.92 67.27* 54.45* Total Total 100.00 100.00 100.00 100.00 TDI is toluene diisocyanate DETA is diethylenetriamine EDA is ethylenediamine *Ten mL of a 10% solution of xanthan gum in propylene glycol was added to stabilize the formulation after it was prepared.

-21- Table Unsatisfactory Clomazone CS Formulations (Components and Weight/Weight Percents) Formulation Component Clomazone Encapsulating Polymer

PMPPI

HDA (40%) Reax 88B® Ethylene Glycol Stabilizer Water Weight (q) V W 300.0 300.0 Percent (Wt/Wt) V W 22.5 24.8 11.6 25.7 476.0 22.5 24.8 5.7 25.7 234.0 34.9 2.6 2.9 1.3 3.0 55.3 49.0 3.7 0.9 4.2 38.2 Total Total 860.6 612.7 100.00 100.00 HDA is 1,6-hexanediamine.

Reax 88B® is a sodium lignosulfonate.

-22- Table 6 Average Particle Size of Microcapsules in Clomazone CS Formulations Formulation

A

B

C

D

E

F

G

H

I

Average Particle Size (um) 26 21 Formulation

J

K

Average Particle Size (urm) 11 17 14 2 9 7 14 21 Particle size was determined using a Malvern Master Sizer MS Table 7 Volatility of Clomazone from CS Formulations as Compared to the Volatility of Clomazone from the Standard, Command® 4 EC Herbicide Formulation

A

B

C

D

E

F

G

H

I

J

K

L

Micrograms of Clomazone Collected 28 30 17 20 8 9 15 13 21 23 24 81 Percent of 4.0 EC 32 33 19 22 8 14 14 17 17 91 110 62 16 14 103 114 100

V

Standard 4.0 EC Standard 4.0 EC 110 126 90-93 *Volatility determined by a different test method.

-23- Table 8 Volatility Effect of Clomazone CS FormulationsCompared to Command® 4 EC Herbicide on Sunflowers in Field Studies Formulation (Test No.) A-1 (1) Command 4 EC A-1 (2) Command 4 EC

P

Command 4 EC Area of Discolored Sunflowers (cm 2 2 6578 12904 17449 37004 256334 788721 Percent Reduction in Area Discolored by Volatility 49.0 52.8 67.5 Table 9 Relative Potency of Clomazone CS Formulations Compared to Command® 4.EC Herbicide against Weed Species in Greenhouse Studies Relative Potency Formulation

A

D

E

P

Barnyardgrass 0.70 0.50 0.19 0.63 Giant Foxtail 0.54 0.59 0.28 0.54 Ye Fc 1 1 ellow Shatter- )xtail cane .35 0.66 .02 0.40 0.95 Green Foxtail 0.95 Velvetleaf 0.69 0.36 0.34 0.90 Too small to measure at rate tested.

Table Efficacy of Clomazone CS Formulation A-1 Compared to Command® 4 EC Herbicide against Weeds in Field Studies Formulation A-1

EC

Percent Control 15 DAE 1 and 30 DAE Pitted Johnsonqrass Bermudaqrass Morninaalory 30 15 30 15 30 68 54 0 1 72 54 85 56 20 55 66 70 Effects on Cotton Sicklepod 15 26 21 Percent Bleaching 0.7 0.5 0.7 0.7 Stand Reduction none none Stunting none none A-1

EC

1 DAE is days after emergence of the test plant species.

Rate of application is 1.0 pound a.i./acre.

-24- Table 11 Efficacy of Clomazone CS Formulation E Compared to Command® 4 EC Herbicide against Certain Weed Species in Field Studies Plant Species Formulation Bamyardgrass Giant Foxtail Yellow Foxtail Green Foxtail Shattercane Johnsongrass Spring Wheat Velvetleaf Percent Control Rate of Application (lb. ai/A) 1 0.25 0.125 E 4 EC E 4 EC E 4 EC 100 100 98 99 91 97 100 100 98 98 95 96 95 93 50 57 50 99 100 83 95 53 68 73 90 33 53 33 100 100 93 97 85 93 55 60 18 26 8 9 100 100 93 96 85 93 Grass Averan e2 95 97 77 83 68 71 1Formulations applied to the plots preemergence.

2 Velvetleaf and Spring Wheat are not included in the grass average. Percent control ratings were determined 20 days after treatment.

Table 12 Efficacy of Clomazone CS Formulation P Compared to Command® 4 EC Herbicide against Weeds in Field Studies Percent Control Plant Species Formulation Velvetleaf Prickly Sida Spotted Spurge Cocklebur Broadleaf Signalgrass Seedling Johnsongrass Large Crabgrass Pitted Morningglory Ivyleaf Morningglory Entire Morningglory 15 DAT P 4 EC 95.0 95.0 89.3 90.5 58.8 72.5 100.0 100.0 30 DAT P 4 EC 97.5 97.55 83.6 90.7 95.0 98.0 58.8 59.4 100.0 100.0 60 DAT P 4 EC 77.3 88.5 87.5 93.5 95.0 95.0 93.0 95.2 92.1 95.0 73.9 70.9 96.0 97.0 95.5 99.0 82.9 89.5 88.0 91.0 73.9 71.6 95.7 99.3 100.0 100.0 78.4 88.5 57.0 77.0 66.9 73.0 99.0 99.0 Morningglory Spp.

Effects on Cotton (Percent)

DAT

P 4 EC 0 0 30 DAT P 4 EC 0 0 Formulation Stand Reduction Stunting 60 DAT P 4 EC 0 0 0 0 0 0.2 Discoloration 1. I, DAT is days after treatment.

Rate of application for both formulations is 0.88 pound a.i./acre.

-26- Table 13 Efficacy of Clomazone CS Formulation P Compared to Command® 4 EC Herbicide against Certain Weeds in Field Studies Percent Control Rate of Application (Ib/A)' A Plant Species 0.25 0.50 0.

Formulation P 4 EC P 4 EC P Redroot Pigweed 73.8 88.8 92.3 97.5 100.0 Velvetleaf 85.0 88.8 91.0 98.3 97.0 Common 92.3 95.0 97.3 100.0 100.0 Bamyardgrass Giant Foxtail 92.5 96.3 98.0 100.0 100.0 Shattercane 65.0 73.8 76.3 96.0 91.3 1 Formulations applied to plots preemergence.

Percent control ratings were determined 18 days after treatment.

75 4 EC 100.0 99.8 100.0 1.00 P 4 EC 100.0 100.0 98.8 100.0 99.8 100.0 100.0 100.0 94.5 100.0 100.0 97.3

Claims (17)

1. An herbicidal composition of microencapsulated clomazone including: a polyurea shell forming microcapsules; and encapsulated material within said shell, said encapsulated material including a herbicidally effective amount of clomazone; wherein said composition has a clomazone volatility less than the volatility of an emulsifiable concentrate of clomazone containing a corresponding concentration of clomazone.

2. The herbicidal composition of claim 1, wherein the clomazone volatility is less than fifty percent that of the emulsifiable concentrate of clomazone.

3. The herbicidal composition of claim 1, wherein the volatility of the composition is reduced compared to an emulsifiable concentrate of clomazone containing a corresponding concentration of clomazone, such that when the composition is applied to a target area, injury to plants in areas adjacent to the target area is reduced.

4. The herbicidal composition of claim 1, wherein the polyurea shell includes one or more polyfunctional amines selected from the group consisting of ethylenediamine (EDA), diethyltriamine (DETA), triethylenetetramine (TETA), and 1,6-hexanediamine (HDA), with the proviso that (EDA) is used only in the presence of a second polyfunctional amine.

The herbicidal composition of claim 1, wherein said polyurea shell is formed by the interfacial polymerization of polymethylene polyphenyl isocyanate and a polyfunctional amine.

6. The herbicidal composition of claim 5, wherein said interfacial polymerization includes the step of: emulsifying an aqueous phase including water and an emulsifier and a water immiscible phase including an isocyanate and clomazone and adding at least one polyfunctional amine to form said microcapsules.

7. The herbicidal composition of claim 1, wherein said encapsulated material further includes a solvent.

8. A process for the preparation of a herbicidally effective clomazone composition including the step of: microencapsulating clomazone by interfacial polymerization to form plural cured microcapsules including a polyurea shell wall surrounding encapsulated material including clomazone, said herbicidally effective clomazone composition having a clomazone volatility less than that of an emulsifiable concentrate of clomazone containing a corresponding concentration of clomazone.

9. A process according to claim 8, wherein said step of microencapsulating includes the step of: curing plural uncured microcapsules including a polyurea shell wall surrounding an encapsulated material including clomazone to form plural cured microcapsules.

A process according to claim 9, wherein said step of microencapsulating further includes the step of: forming a dispersion of plural uncured microcapsules, each including a polyurea shell wall surrounding an encapsulated material including clomazone, by emulsifying an aqueous phase including water and an emulsifier and a water immiscible phase including an isocyanate and clomazone and adding at least one polyfunctional amine; wherein step is conducted before step

11. A process according to claim 10, wherein said step of microencapsulating further includes the step of: providing an aqueous phase including water and an emulsifier and a water immiscible phase including an isocyanate and clomazone; wherein step is conducted before step

12. A process according to any one of claims 8 to 11 further including the step of: adjusting the pH of the composition to between 6.5 to 9.0; wherein step is conducted after step

13. A process according to any one of claims 9 to 12, wherein said plural uncured microcapsules are cured by heating said microcapsules at a temperature sufficient and for a time sufficient to form plural cured microcapsules.

14. A process according to any one of claims 10 to 13, wherein said polyfunctional amine is selected from the group consisting of ethylenediamine (EDA), diethyltriamine (DETA), triethylenetetramine (TETA), and 1,6- hexanediamine (HDA), with the proviso that EDA is used only in the presence of a second polyfunctional amine.

A process according to any one of claims 10 to 14, wherein said isocyanate is polymethylene polyphenyl isocyanate (PMPPI).

16. A process according to any one of claims 10 to 15, wherein said water immiscible phase further includes a solvent and said encapsulated material further includes a solvent.

17. A process according to any one of claims 8 to 16, wherein said aqueous phase further includes an antifoam agent and a viscosity modifier/stabiliser. DATED this 6th day of May 1999. FMC CORPORATION WATERMARK PATENT TRADEMARK ATTORNEYS 290 BURWOOD ROAD HAWTHORN VICTORIA 3122 AUSTRALIA