SLOW RELEASE FORMULATIONS OF PHOSPHOROUS ACID AND PHOSPHITE SALTS

Abstract

An agrochemical composition comprising: an absorbent cellulosic carrier with one or more metal compound(s) incorporated into the carrier, and an active agent selected from the group consisting of phosphorous acid and phosphite salts that contain the monovalent anion [HP(O)(OX)(O.sup.)], where X is H or CH.sub.2CH.sub.3.

Claims

1. An agrochemical composition comprising: an absorbent cellulosic carrier with one or more metal compound(s) incorporated into the carrier, and an active agent selected from the group consisting of phosphorous acid and phosphite salts that contain the monovalent anion [HP(O)(OX)(O.sup.)], where X is H or CH.sub.2CH.sub.3.

2. An agrochemical composition according to claim 1, wherein the absorbent cellulosic carrier is in the form of granules.

3. An agrochemical composition according to claim 1, wherein the absorbent cellulosic carrier in the form of shredded paper selected from the group consisting of filter paper, blotting paper, chromatography paper and cellulose pulp sheets, to which was added one or more basic metal compounds, at a concentration of not less than 1% by weight.

4. An agrochemical composition according to claim 1, wherein the metal compound is a basic metal compound selected from the group consisting of an alkaline earth metal oxide, carbonate or hydroxide.

5. An agrochemical composition according to claim 1, wherein the phosphite salt is selected from the group consisting of M.sup.n+(H.sub.2PO.sub.3.sup.).sub.n, where n is 1, and M is a monovalent counter cation.

6. An agrochemical composition according to claim 5, wherein the phosphite salt is monoammonium or monopotassium phosphite.

7. An agrochemical composition according to claim 1, wherein the phosphite salt is Fosetyl-Aluminum Al[HP(O)(OCH.sub.2CH.sub.3)(O.sup.)].sub.3.

8. An agrochemical composition according to claim 1, further comprising a salt of phosphorous acid which contains the divalent anion (HPO.sub.3).sup.2.

9. An agrochemical composition according to claim 8, wherein the salt is the diammonium or dipotassium salt of phosphorous acid.

10. An agrochemical composition according to claim 1, which is a fungicidal composition, a nematocidal composition or a fertilizer composition.

11. A process for the preparation of a controlled-release agrochemical composition, comprising impregnating an absorbent cellulosic carrier with an aqueous solution of an active agent selected from the group consisting of phosphorous acid and water-soluble phosphite salts that contain the monovalent anion [HP(O)(OX)(O.sup.)], where X is H or CH.sub.2CH.sub.3; and optionally with an aqueous solution of a divalent salt of phosphorous acid.

12. A method of supplying phosphorous acid or a monovalent phosphite salt to a plant, optionally in admixture with a divalent salt of the acid, the method comprises applying the composition of claim 1 to a soil or growth medium.

13. A method according to claim 12, which is a method of protecting a plant against a fungal disease or a nematode attack.

14. A method comprising application in-furrow of the composition of claim 1 at the time of planting of a plant selected from the group consisting of Solanaceae, Brassicaceae/Cruciferae and Cucurbitales.

15. A method according to claim 14, further comprising application of one or more organic fungicides to the plant or the growth medium.

16. A method according to claim 15, wherein the plant is potato and the organic fungicides are applied to protect the potato from late blight and/or early blight.

17. A method according to claim 15, wherein the one or more organic fungicides are applied by foliar spray.

18. A method according to claim 17, wherein the composition applied in-furrow comprises absorbent cellulosic carrier in the form of granules, wherein the granules contain monoammonium phosphite as the active agent.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0038] FIG. 1 is a DAP-Biodac FTIR spectrum.

[0039] FIG. 2 is a MAP-Biodac FTIR spectrum.

[0040] FIG. 3 shows a plot of the release rate of the phosphites from Biodac granules versus time.

[0041] FIG. 4 shows a plot of the release rate of the phosphites from Biodac granules, made by the test method of WO 02/049430, in comparison with the results presented in WO 02/049430.

[0042] FIG. 5 shows a plot of the release rate of MAP and DAP from Biodac granules and paper strips-CaCO.sub.3 versus the number of irrigation cycles based on the test method of WO 02/049430.

[0043] FIG. 6 shows a plot of the release rate of the phosphites from Biodac granules to the soil versus the amount of added water.

[0044] FIG. 7 shows a plot of the release rate of MAP, DAP and Fosetyl-Al from Biodac granules to the soil versus the amount of added water.

[0045] FIG. 8 shows a plot of the release rate of the DAP and MAP from different carriers to the soil versus the amount of added water.

EXAMPLES

Materials and Methods

[0046] Potassium phosphite, ammonium hydroxide (25% solution) and phosphorous acid (98% purity assay) were purchased and used without further purification. Fosetyl-Aluminum technical grade was obtained from Sigma Aldrich. Biodac 12/20 mesh and Biodac 20/50 mesh were purchased from Kadant Grantek Inc. Filter papers used for the experiments were obtained from Whatman.

[0047] The present invention was demonstrated using red loam soil.

Analytical Methods

[0048] The ion exchange chromatography (IC) for the determination of phosphite concentration was carried out using a Metrohm Compact IC Flex chromatography system.

[0049] Iodometric titration was performed using a potentiometric redox method (see, for example, Anal. Chem. 1953, 25, 8, 1272-1274: Determination of Hypophosphorous and Phosphorous Acids by R. T. Jones and E. H. Swift].

[0050] FTIR spectrums were recorded on the Agilent spectrometry instrument.

Preparations 1 to 5

Solutions of Phosphorous Acid and Phosphite Salts Containing the Equivalent of 30% of Phosphorous Acid

[0051] 1) Phosphorous acid, 32%

[0052] Phosphorous acid (32.7 g; 98% purity assay) was dissolved in 67.3 g of water under stirring to obtain a clear solution (pH=0.1).

[0053] 2) Monopotassium phosphite (MPP) (32% H.sub.3PO.sub.3)

[0054] KH.sub.2PO.sub.3 (47 g) was dissolved in 53 g of water under stirring to obtain a clear solution (pH=4.0-4.5).

[0055] 3) Monoammonium phosphite (MAP) (32% H.sub.3PO.sub.3)

[0056] Phosphorous acid (32.7 g; 98% purity assay) was dissolved in 41 g of water under stirring. 26.1 g of NH.sub.4OH solution (25%) was added slowly to react with the acid to obtain a clear solution of the MAP salt (pH=4.0-4.5)

[0057] 4) Diammonium Phosphite (DAP) (32% H.sub.3PO.sub.3)

[0058] Phosphorous acid (32.7 g; 98% purity assay) was dissolved in 15.1 g of water under stirring. 52.2g of NH.sub.4OH solution (25%) was added slowly to react with the acid to obtain a clear solution of the DAP salt (pH=6.0-7.0).

[0059] 5) Fosetyl-Aluminum

[0060] Fosetyl-Aluminum (1 g; technical grade) was dissolved in 9 g of water under stirring to obtain a clear solution of Fosetyl-Aluminum.

Examples 1-12

Loading Solutions of Phosphorous Acid and Phosphite Salts onto Cellulosic Carriers

[0061] Three types of carriers were used: 1) cellulosic granules Biodac 12/20 and 20/50; 2) paper strips; and 3) paper strips to which calcium carbonate was added.

[0062] Examples 1 to 7: Biodac 12/20 granules (200g) were mixed uniformly with each of the phosphorous acid, MPP, MAP and DAP solutions described in preparations 1 to 4, and with some combinations of these solutions (the total weight of solution(s) added to the granules was 100 g), to obtain ACID-Biodac, MPP-Biodac, MAP-Biodac, DAP-Biodac and MPP/DAP-Biodac granules respectively. The granules, with an active ingredient loading of about 10-11% looked dry, were flowable, and showed slight alkalinity when added to water at 5% by weight concentration (pH of 7.5-8.0), except for ACID-Biodac (pH=5.4).

[0063] Example 8: Biodac 20/50 granules (90 g) were mixed uniformly with the Fosetyl-Aluminum solution (10 g) described in preparation 5 to obtain Fosetyl-Aluminum-Biodac granules.

[0064] Examples 9 and 10: Paper strilps (2 g) were mixed each of the MAP and DAP solutions of preparations 3 and 4, to obtain MAP-paper strips or DAP-paper strips granules respectively.

[0065] Examples 11 and 12: the carriers were paper strips, to which calcium carbonate was added. Paper strips (5 g), CaCO.sub.3 (0.6 g) and water (9 g) were mixed uniformly. Then, either a MAP or a DAP solution of preparations 3 or 4 was added and the mass was uniformly mixed to obtain MAP-paper strips-CaCO.sub.3 or DAP-paper strips-CaCO.sub.3 respectively, all with an essentially dry aspect. Table 2 summarizes the compositions which were prepared.

TABLE-US-00002 TABLE 2 Example Carrier Solution (s) added 1 (invention) Biodac (R) (200 g) H.sub.3PO.sub.3 (100 g) 2 (invention) Biodac (R) (200 g) KH.sub.2PO.sub.3 (100 g) 3 (invention) Biodac (R) (200 g) (NH.sub.4) H.sub.2PO.sub.3 (100 g) 4 (comparative) Biodac (R) (200 g) (NH.sub.4) .sub.2HPO.sub.3 (100 g) 5 (invention) Biodac (R) (200 g) KH.sub.2PO.sub.3 + (NH.sub.4) .sub.2H.sub.2PO.sub.3 (75 g + 25 g) 6 (invention) Biodac (R) (200 g) KH.sub.2PO.sub.3/(NH.sub.4) .sub.2H.sub.2PO.sub.3 (50 g + 50 g) 7 (invention) Biodac (R) (200 g) KH.sub.2PO.sub.3/(NH.sub.4) .sub.2H.sub.2PO.sub.3 (25 g + 75 g) 8 (invention) Biodac (R) (90 g) Al [HP (O) (OCH.sub.2CH.sub.3) (O.sup.)].sub.3 (10 g) 9 (comparative) Paper strips (2 g) (NH.sub.4) H.sub.2PO.sub.3 (1 g) 10 (comparative) Paper strips (2 g) (NH.sub.4) .sub.2HPO.sub.3 (1 g) 11 (invention) Paper strips (5 g)+ (NH.sub.4) H.sub.2PO.sub.3 (1 g) CaCO.sub.3 (0.6 g) 12 (comparative) Paper strips (5 g)+ (NH.sub.4) .sub.2HPO.sub.3 (1 g) CaCO.sub.3 (0.6 g)

Examples 13 to 18

Release Tests of Phosphite from Cellulosic Carriers: Evaluation by Filtration Experiments

[0066] A flask fitted with a conical filter paper was used for the experiments. The granules of Examples 2 to 7 (10 g) were placed on the filter paper and were then water-soaked with 80 ml of water. The concentration of the phosphite in the filtrate was determined by iodometric titration. Release rates are shown in FIG. 3 versus time (Examples 13 to 18 correspond to the testing of the granules of Examples 2 to 7, respectively).

[0067] The results are shown in FIG. 3 indicate dissimilarity between the behavior of monovalent salts [KH.sub.2PO.sub.3 and (NH.sub.4)H.sub.2PO.sub.3], which are released slowly, as opposed to divalent salts [(NH.sub.4).sub.2HPO.sub.3], which are released rapidly. Mixed monovalent/divalent salts loaded onto Biodac granules show a trend of increasing release rate with the increasing proportion of the divalent salt in the blend.

Examples 19 (Invention) and 20 to 23 (Comparative)

Release Tests of Phosphite from Cellulosic Carriers: Evaluation by the Experimental Set-Up of WO 02/49430

[0068] In WO 02/049430, the release profile of phosphites from the coated carriers was evaluated by mixing the tested carrier (1 g) with water (2 ml) and allowing the mixture to stand for two hours. Next, the supernatant was collected, and the concentration of phosphorous acid was measured by high pressure liquid chromatography. The cycle was repeated ten times, to simulate conditions of irrigation by sprinkling. Results are reported in Table 1 on page 21 of WO 02/49430.

[0069] A similar approach was used to test the carriers of the invention. 2 g of the carriers of Examples 3 and 4 (0.2 g of phosphite content) were mixed with 8 ml of water. The supernatant was collected after two hours and the concentration of phosphorous acid was measured by ion chromatography (IC). The cycle was repeated ten times.

[0070] The results are presented graphically in FIG. 4, showing the cumulative percentage of phosphite released from the tested carrier versus cycle numbers. The slowest release rate was demonstrated by the carrier of the invention, MAP-Biodac, as opposed to the DAP-Biodac, from which the active agent was released fairly rapidly (identified as Examples 19 and 20 in FIG. 4). The coated carriers of WO 02/49430 provided higher levels of active agent compared to MAP-Biodac, i.e., they are less effective as slow-release compositions (identified as Examples 21-23 in FIG. 4; plots for the three prior art carriers were generated based on Table 1 on page 21 of WO 02/49430).

Examples 24 and 25

Release Tests of Phosphite from Cellulosic Carriers: Evaluation by the Experimental Set-Up of WO 02/49430

[0071] The carriers of Examples 11 and 12, which were produced by absorbing calcium carbonate on paper strips, followed by soaking with a solution of MAP and DAP, respectively, were tested by the experimental set-up of WO 02/49430.

[0072] The results are shown in FIG. 5. To enable easy comparison, the curves corresponding to MAP-Biodac and DAP-Biodac are reproduced. It is seen that the monovalent salts are released in comparably slower rate from the cellulosic granular carrier Biodac and the CaCO.sub.3-added paper strips. The release rate demonstrated by the diammonium salt is considerably faster from both carriers.

Examples 26 to 28 (Invention) and 29 (Comparative)

Release Tests of Phosphite from Cellulosic Carriers: Evaluation in Soil

[0073] Each sample consists of soil (130 g) mixed with 2 g of a phosphite formulation. The formulations tested were:

[0074] ACID-Biodac of Example 1 (corresponding to Example 26);

[0075] MPP-Biodac of Example 2 (corresponding to Example 27);

[0076] MAP-Biodac of Example 3 (corresponding to Example 28); and

[0077] DAP-Biodac of Example 4 (corresponding to Example 29).

[0078] The amount of phosphite in all samples was the same (0.2 g). 0.4-liter flowerpots were filled with the soil samples. A total number of twelve flowerpots were used, equally divided into four groups, such that each group consisted of three replicates of each sample treated with the same formulation.

[0079] Overhead irrigation was applied, supplying a metered amount of water (400 mL) to cause water draining. The drained water was collected, weighed and the phosphite concentration was determined by IC.

[0080] The results are shown graphically in FIG. 6. The ordinate indicates the cumulative percentage of active agent released from the granular carrier (group average). The lower abscissa is the cumulative volume of water added, and the upper abscissa is the time scale (the experiment lasted ten days; water was added four times on day zero, twice on the first day, and once during the sixth, seventh, eighth and ninth days). The results indicate that the free acid and the monovalent salts are released more slowly from the cellulosic granular carrier, compared to the divalent salt.

Examples 30 (Comparative) and 31 (Invention)

Release Tests of Fosetyl-Aluminum from a Cellulosic Carrier: Evaluation in Soil

[0081] The sample for Example 30 was prepared by mixing soil (130 g) with 1 g of a solution containing 10% of Fosetyl-Aluminum technical as described in Preparation 5. The sample for Example 31 was prepared by mixing 130 g of soil with 10 g of Fosetyl-Aluminum-Biodac formulation prepared as described in Example 8.

[0082] 0.4-liter flowerpots were filled with the soil samples. A total number of six flowerpots were used, equally divided into two groups, such that each group consisted of three replicates of each one of the samples treated with the same formulation.

[0083] Overhead irrigation was applied, supplying a metered amount of water (400 mL) to cause water draining. The drained water was collected, weighed and the phosphite concentrations were determined by IC.

[0084] The results are shown graphically in FIG. 7. The ordinate indicates the cumulative percentage of active agent released from the samples. The lower abscissa is the cumulative volume of water added, and the upper abscissa is the time scale. The results indicate that the cellulosic carrier can be used to slow down the release rate of phosphite from Fosetyl-Aluminum (see the curves corresponding to Examples 30 and 31 in FIG. 7). Monovalent phosphite salts (MAP, which contains the (H.sub.2FO.sub.3).sup. anion, and Fosetyl-Aluminum, which contains the organic phosphite [HP(O)(OCH.sub.2CH.sub.3)(O.sup.)] anion), behave in a similar manner when absorbed into the cellulosic carrier, showing a relatively slow release rate of the phosphite.

Examples 32-33 and 35 (Comparative) and 34 (Invention)

Release Tests of Phosphite from Cellulosic Carriers: Evaluation in Soil

[0085] Soil samples were prepared. Each sample consists of soil (130 g) mixed with 2-16 g of a phosphite formulation in such a way that the final concentration of phosphorous acid will be the same in all samples. The formulations tested were:

[0086] MAP-paper strips of Example 9 (corresponding to Example 32);

[0087] DAP-paper strips of Example 10 (corresponding to Example 33);

[0088] MAP-paper strips-CaCO.sub.3 of Example 11 (corresponding to Example 34); and

[0089] DAP-paper strips-CaCO.sub.3 of Example 12 (corresponding to Example 35).

[0090] The amount of the formulation was adjusted to provide a constant quantity of phosphite (0.2 g) in each sample.

[0091] 0.4-liter flowerpots were filled with the soil samples. A total number of twelve flowerpots were used, equally divided into four groups, such that each group consisted of three replicates of each sample treated with the same formulation.

[0092] Overhead irrigation was applied, supplying a metered amount of water (400 mL) to cause water excess draining. The drained water was collected, weighed and the phosphite concentrations were measured by IC.

[0093] The results are shown graphically in FIG. 8. The ordinate indicates the cumulative percentage of active ingredient released from the granular carrier (group average). The lower abscissa is the cumulative volume of water added, and the upper abscissa is the time scale (the experiment lasted ten days; water was added four times on day zero, twice on the first day, and once on the sixth, seventh, eighth and ninth days). The results attest to the role of calcium source in suppressing the release of phosphite and show the same trend observed with the Biodac carrier: a monovalent salt is released more slowly from the cellulosic carrier compared to the divalent salt.

Examples 36-40

Control of Pink Rot in Potato Using Mono-Ammonium Phosphite Released from a Cellulosic Carrier: a Field Study

[0094] The goal of the study was to evaluate the effect achieved by releasing MAP from the cellulosic carrier on Pink Rot in potatoes (a disease caused by Phytophthora Erythroseptica, a soil-borne pathogen).

[0095] For the study, potato for the growth of baby tubers of the Mary Spears variety was used. The potato was grown in sandy soil, in a field known to be infested with the pathogen. The experimental design consisted of four different treatments and one control group. A total of twenty sowing strips, each 15 m long, were divided equally and randomly between the four treatment and control groups (that is, four repetitions per treatment/control). After sowing without covering, the tested material was spread or sprayed on the seeds and then mechanical covering was performed. The treatments include the application of 2.5 and 5 Kg per 1000 m.sup.2 of ammonium mono-phosphite in the form of the 10% granular preparation of Example 3 (Examples 38, 39) and the application of suspension concentrate (SC) formulation of fluazinam (60 g/liter)/phosphorous acid (420 g/liter) at a rate of 2.5 and 5 liter per 1000 m.sup.2 (Examples 36, 37). Water was supplied by sprinkling and drip irrigation systems.

[0096] At the end of the 60 days growth period, tubers were counted in each plot (strip) and crop (in kg) was determined for each plot (strip).

[0097] The results (averaged over the repetitions) are shown in Table 3. It is worth noting that plant health assessments were performed and no phytotoxicity was observed in any of the treatments. Also, the tubers were examined in a laboratory to determine the level of residual phosphite, and no phosphite was found.

TABLE-US-00003 TABLE 3 The average Crop, number of Example Treatment Dosage Kg tubers 36 Fluazinam + PA 2.5 L/1000 m.sup.2 6.98 176.3 (comparative) 37 Fluazinam + PA 5.0 L/1000 m.sup.2 6.64 133.8 (comparative) 38 (invention) MAP-Biodac 2.5 kg/1000 m.sup.2 7.50 190.3 39 (invention) MAP-Biodac 5.0 kg/1000 m.sup.2 7.22 174.0 40 Control 6.37 157.5

[0098] The treatments with MAP-Biodac lowered the disease severity index, both in the treatment with 2.5 kg/1000 m.sup.2 and with 5.0 kg/1000 m.sup.2 of MAP-Biodac. An increase of the crop was observed. The effect is also seen in the number of tubers.

Examples 41-43

Effect of Mono-Ammonium Phosphite Released from a Cellulosic Carrier on Potato: a Field Trial

[0099] A field trial was conducted to determine the effect achieved by releasing MAP from the cellulosic carrier on plant vigor and yield in potato. The plots were arranged in a randomized complete block design with six replications. Each plot consisted of two 25-foot-long and 3-foot-wide rows. Soil applications were made into opened furrows, followed by planting of potato Atlantics seed pieces with 8-in in-row plant spacing on 36-in row spacing. Fertilizer (10:10:10 in N:P:K) was applied at 350 lb/A. The soil contained 1.3% organic matter, and the pH was 5.6. Chemicals were applied in the soil at planting on 20 Mar. 2023; monthly precipitations were 1.45, 6.95, 2.09, and 2.23.7 inches, and monthly high temperatures were 86, 87, 85, and 92 F. in March, April, May, and June, respectively. Plant emergence was counted on 21 Apr. Coragen at 12.0 oz/A was used for controlling of insects.

[0100] The treatments and the results are tabulated in Table 4. In addition to nontreated control group (Example 41), a comparative treatment (Example 42) consisted of conventional application by foliar spray of a mixture of commercial fungicides against potato blight. The commercial fungicides were applied in an alternate manner according to their acceptable application rates. The treatment of the invention consisted of application at planting of MAP-Biodac, adjacent to the planted seed pieces, at application rate of 600Z WT/1000 row-FT, and subsequently, at an appropriate time, application by foliar spray of a pair of commercial fungicides against potato blight.

[0101] Each treatment was evaluated by determining the marketable yield: tubers with a diameter equal to or greater than 1.5 inches were counted as marketable yield. Data were analyzed using the ARM (Gylling Data Management). The details and the results are tabulated in Table 4.

TABLE-US-00004 TABLE 4 Marketable Example Treatment application yield* (lb) 41 (reference) Non-treated control 16.0b 42 (comparative) Fungicide X Foliar spray 17.9b Fungicide Y Foliar spray 43 (invention) MAP-Biodac, In-furrow 23.5a 60 OZ WT/1000 row-FT Foliar spray Fungicide X Foliar spray Fungicide Y *a, b: statistical significance

[0102] A significant increase in plant vigor was observed in the MAP-Biodac treatment. In-furrow MAP-Biodac at planting at application rate of 600Z WT/1000 row-FT (Example 43) shows a significant improvement in yield compared to the grower standard (Example 42) and non-treated control (Example 41). No phytotoxicity was observed between treatments.