AU741341B2 - Fungicidal compositions for plants containing phosphonate and phosphate salts, and derivatives thereof - Google Patents

Description

WO 99/15017 PCT/US97/16997 FUNGICIDAL COMPOSITIONS FOR PLANTS CONTAINING PHOSPHONATE AND PHOSPHATE SALTS, AND DERIVATIVES

THEREOF

Background of the Invention The present invention is broadly concerned with fungicidal compositions, and methods of use, which provide improved efficacy in controlling parasitic fungi in plants. More particularly, the compositions and methods of use of the invention include fungicidally effective amounts of both phosphate, preferably in the form of either mono or dipotassium phosphate (KH 2

PO

4

K

2

HPO

4 and phosphonate, preferably in the form of either mono or dipotassium phosphonate (KH 2

PO

3

K

2

HPO

3 in aqueous solution.

Phosphorus is an essential major element in plant nutrition because it governs the energy producing reactions, including those that are oxidative, and photophosphorylative and the production of adenosine diphosphate (ADP) and adenosine triphosphate (ATP). Energy-rich phosphate bonds of ADP and ATP provide the energy for many of the physiological reactions that occur in plants.

The element phosphorous appears in two general forms that concern the present invention phosphonate and phosphate. The term "phosphonate," sometimes also referred to as "phosphite," means the salts (organic or inorganic) of either phosphonic acid or phosphorous acid. Phosphonic and phosphorous acids have the formula H 3

PO

3 and a molecular weight of 82.00. Their structures from the International Union of Pure and Applied Chemistry are shown below: WO 99/15017 PCT/US97/16997 OH

OH

I

I

H P O HO-P OH

OH

Phosphonic Acid Phosphorous Acid CA: 13598-36-2 CA: 10294-56-1 The term "phosphate" means the salts (organic or inorganic) of phosphoric acid having the formula H 3

PO

4 molecular weight of 98, and has the following structure: 0 HO P OH

I

OH

Phosphoric Acid CA: 7664-38-2 In the past, various phosphonate compounds have been proposed as useful in fungicidal and fertilizer compositions for application to plants. See, e.g. U.S. Patent Nos. 4,075,324 and 4,119,724 to Thizy, describing phosphorous acid, its inorganic and organic salts, as a plant fungicide; U.S. Patent No. 4,139,616 to Dueret, describing fungicidal compositions based on phosphorous acid esters and salts thereof; U.S. Patent No. 4,542,023 to Lacroix et al., describing organophosphorous derivatives as possessing systemic and contact fungistatic and fungicidal activity; U.S.

Patent Nos. 4,698,334 and 4,806,445 and 5,169,646 to Horriere et al., describing WO 99/15017 PCT/US97/16997 fungicidal compositions based on alkyl phosphonates; U.S. Patent Nos. 4,935,410 and 5,070,083 to Barlet, describing fungicidal aluminum tris-alkyl-phosphonate compositions; and U.S. Patent No. 5,514,200 to Lovatt, describing formulations of phosphorous-containing acid fertilizer for plants. (The teachings of the proceeding U.S.

Patents are hereby incorporated by reference.) The above references disclose phosphonate compositions have been found to be effective for protecting plants, and particularly grape vines, citrus and fruit trees and tropical plants, against fungal attack.

Once assimilated, phosphonates have been shown to enhance the phytoimmune system. The phosphonate induced stimulation of the phytoimmune system is triggered by the induction of ethylene production, followed by a rapid accumulation of phytoalexins at the site of infection. Phosphonates have also been shown to have detrimental effect on the growth of Phycomycetes. See, Pegg, K.G. and deBoer, R.F., "Proceedings of the Phosphonic (Phosphorous) Acid Work Shop,"Australiasian Plant Pathology, Vol. 19 1990.

In accordance with this development of the present invention, however, it has recently been discovered that phosphonates exacerbate the non-target Ascomycete fungi, producing an eiphytotic outbreak of much greater magnitude than the infections occurring without phosphonate treatment. This phenomenon is known as pathological acerbation.

In the past, phosphates were not viewed as a solution to pathological acerbation of Ascomycete fungal infections. This is because phosphates are viewed primarily as a fertilizer with only limited, or even detrimental, fungical properties. For example, U.S. Patent 5,514,200 teaches that phosphate fertilizers inhibit beneficial symbiosis WO 99/15017 PCT/US97/16997 between plant roots and mycorrhizal fungi, and further promote bacterial and fungical growth in the rhizosphere, including the growth of pathogenic fungi and other small soil-borne organisms. (Col. 2, lines 18-28). Phosphates have also been considered to be a competitive inhibitor for phosphonate assimilation, thus inhibiting the ability of phosphonates to protect against fungus attack. See, Pegg, K.G. and deBoer, R.F., "Proceedings of the Phosphonic (Phosphorous) Acid Work Shop,"Australiasian Plant Pathology, Vol. 19 pp. 117 and 144, 1990. Yet further, phosphonates and phosphates were believed to be "biological strangers," with the presence of phosphonates or its esters, exerting little or no influence on enzyme reactions involving phosphates. Robertson, H.E. and Boyer, "The Biological Inactivity of Glucose 6 phosphonate, Inorganic Phosphites and Other Phosphites," Archives of Biochemistry and Biophysics, 62 pp. 380-395 (1956).

Accordingly, the requirements for a successful phosphonate-based fungicide depend on the elimination of the phosphonate-induced pathological ascerbation of Ascomycete fungical infections.

Summary of the Invention The present invention addresses the problems outlined above, and provides an improved anti-fungicidal composition for plants that contains, as active ingredients, fungicidally effective amounts of both phosphonates and phosphates. According to the present invention, it has been discovered that the application to a plant of the inventive phosphonate/phosphate composition substantially eliminates pathological acerbation of Ascomycete fungi, while at the same time, provides a means to control Phycomycetes and Ascomycetes with a single product.

In a first aspect the invention provides a fungicidal composition for controlling fungus disease in plants comprising: a fungicidally effective amount of at least a first salt selected from a group consisting of K 2

HPO

3

KH

2

PO

3 and K 3

PO

3 and a second salt selected from a group consisting ofK 2

HPO

4

KH

2

PO

4 and K 3 P0 4 In a second aspect, the invention provides a method of controlling fungus disease in plants comprising: applying to the plants in fungicidally effective amounts at least a first salt selected from a group consisting of K 2

HPO

3 KH2PO 3 and K 3

PO

3 and a second salt selected from a group consisting ofK 2

HPO

4

KH

2 P0 4 and

K

3 P0 4 In a third aspect, the invention provides a fungicidal composition for controlling fungus in plants comprising: a fungicidally effective amount of at least a first salt having the following 15 formula: **2 9*

R

2 R-O-P-0- Men O P OH 0 Where R, is selected from group consisting of H, K, an alkyl radical containing from 1 to 4 carbon atoms, halogen-substituted alkyl or nitro-substituted alkyl radical, 2 an alkenyl, halogen-substituted alkenyl, alkinyl, halogen-substituted alkinyl, alkoxysubstituted alkyl radical, a onium substituted by alkyl or hydroxy alkyl radicals; eg 30 R3 Where R is selected from group consisting of H, K, an alkyl radical containing from 1 to 4 carbon atoms, halogen-substituted alkyl or nitro-substituted alkyl radical, an alkenyl, halogen-substituted alkenyl, alkinyl, halogen-substituted alkinyl, alkoxysubstituted alkyl radical, ammonium substituted by alkyl or hydroxy alkyl radicals;

R

2 and R 3 are selected from a group consisting of H and K; Me is selected from a group consisting of K, alkaline earth metal cations, or aluminum atom; ammonium cation; and n is a whole number from 1 to 3, equal to the valence of Me; and wherein at least one of RI and R 3 in the second salt is K.

In a fourth aspect, the invention provides a method of controlling fungus disease in plants comprising applying to the plants in enhanced fungicidally effective amounts a composition comprising: an aqueous solution of H 3 PO3 and KOH, and an aqueous solution ofmonopotassium phosphate and KOH.

In a fifth aspect, the invention provides a method of controlling fungus disease in plants comprising applying to the plants in enhanced fungicidally effective amounts a composition prepared by mixing: an aqueous solution of H 3 PO3 and KOH, and an aqueous solution of monopotassium phosphate and KOH.

:*In a sixth aspect, the invention provides a method of controlling fungus .disease in plants comprising applying to the plants in enhanced fungicidally effective amounts a composition comprising: an aqueous solution of H 3 PO3 and KOH, and an aqueous solution of dipotassium phosphate.

In a seventh aspect, the invention provides a method of controlling fungus disease in plants comprising applying to the plants in enhanced fungicidally effective amounts a composition prepared by mixing: an aqueous solution of H 3

PO

3 and KOH, and an aqueous solution of dipotassium phosphate.

In one embodiment fungicidal compositions may be used for the protection of citrus and fruit trees and vines.

The composition preferably comprises an aqueous solution wherein each salt is present in solution from about 20 millimolar to about 5% vol./vol.

5A According to another embodiment, the amount of the first salt is one part by weight and the amount of the second salt is between 0.001 and 1,000 parts by weight.

Phosphonate salts useful in the practice of the invention also include those organic and inorganic salts taught by U.S. Patent Nos. 4,075,324 and 4,119,724 to Thizy et al., (see, col. 1, In. 51-69 through col. 2, In. 1-4).

A Detailed Description of the Preferred Embodiment.

The following examples set for preferred concentrations and techniques for formulation thereof, as well as methods of application and use and test results demonstrating the efficacy of the inventive concentration in protecting plants against attack by Ascomycete and Phycomycete fungi. It is to be understood, however, that these Examples are presented by way of illustration only and nothing therein shall be taken as a limitation upon the overall scope of the invention. The specific components .tested in the Examples were prepared and applied as follows.

Method of Preparation A. Potassium Phosphonate (KH 2 PO,) Aqueofs Solution. H3PO 3 is produced by the hydrolysis of phosphorus trichloride according to the reaotion: PCI 3 3H 2 0

H

3 P0 3 3HC1. The HCI is removed by stripping under reduced pressure and the phosphonic acid (H 3

PO

3 is sold as a 70% acid solution.

The phosphonic acid is then neutralized in aqueous solution by potassium hydroxide according to the reaction: H3PO 3 KOH KH 2

PO

3

H

2 0 to about pH and to produce a 0-22-20 liquid weighing 11.15 Ibs./gal. This solution is -6 commercially available and is sold under the trademark "Phos-Might" by Foliar Nutrients, Inc., Cairo, GA 31728.

B. Potassium Phosphate (KJHPO) Aqueous Solution. Mono potassium phosphate (0-51.5-34) is reacted with 45% potassium hydroxide in aqueous solution to produce dipotassium phosphate by the following reaction: This solution is commercially available and is sold under trademark "K-Phos" by Foliar Nutrients, Inc., Cairo, GA 31724

KH

2

PO

4 KOH K 2 HP04 H 2 0 with a product density of 1.394 at and a solution pH of 7.6 producing a 0-18-20 analysis.

C. KH 2

POK

2 HPO, Solution. Varying amounts of each compound

(K

2

HPO

3

;KH

2

PO

3

K

2

HPO

4 or KH 2

PO

4 in aqueous solution are combined at rates ranging from 20 millimolar to 5% vol./vol., depending on crop host and the pathogen complex and level of infection.

*Method of Application The preferable method of application is foliar, either by ground or aerial equipment, but is not limited to that method alone. Injection or soil applications, for

C

example, could also be efficacious depending on specific crops afrd pathogens.

The inventive compositions have utility on fruit crops, agronomic crops, ornamentals, trees, grasses, vegetables, grains, and floricultural crops, as well as, o 1 some aquatic crops including water cress.

The fungicidal properties of the compounds according to the invention are various, but are particularly interesting in the case described in the following examples: WO 99/15017 PCT/US97/16997 Examples 1-5 exemplify a portion of these applications. In Examples 1-4, fungicidal treatments were applied to ornamentals, citrus and vegetables. In each of Examples 1-4, treatments were applied as a one gallon solution by a back pack sprayer, maintained at about 60 psi, in sufficient quantities of water to achieve thorough coverage.

All treatments were applied to the appropriate number of experimental units assigned in a randomized complete block (RCB) design replicated four times. Example was a pre-harvest fungicidal spray evaluation on "Nova" tangelos.

As used in the examples, "percent infection" means percent of leaves that exhibit fungus lesions. "Phytotoxicity" means number crop injury to leaves that fell off the plant following the application of the solution.

The Ascomycete fungi were the subjects of testing in Examples 1 through 5 and are all members of the Ascomycete family.

EXAMPLE NO. 1 Dogwood\Powdery Mildew Fungicide Trial Trail Ridge Nursery, Keystone Hts., Florida The compounds according to the invention are studied for the effect on the powdery mildew (Oidium Spp.), which is responsible for foliar infections in dogwood.

Potassium phosphonate and potassium phosphate solutions were applied in compositions as set forth in Table 1 below. An average of 5 six-inch pots per experimental unit with 4 repetitions in a randomized complete block design were considered. The solutions were applied to Dogwood (Cornis Florida Var.

"Weaver'). The application of the compositions were made in April 25, 1996, May WO 99/15017 PCT/US97/16997 8, 1996, and May 23, 1996. The effects of the various compositions were rated on May 30, 1996.

Table 1 shows that when a potassium phosphonate solution (containing no appreciable amount of phosphate) is applied to dogwood, pathological acerbation of the Ascomycete fungus occurs in 100 percent of the dogwood leaves, in contrast to the control, which exhibited only 30 percent infection. The inventive composition that combine potassium phosphate and potassium phosphonate showed a complete elimination of the pathological acerbation phenomenon, and in fact, dropped the amount of infection by about 20 percent.

TABLE 1 TREATMENT RATE/100 gal.

1) POTASSIUM PHOS- 1% PHONATE SOLUTION 2) POTASSIUM PHOS- 1% PHATE SOLUTION 3) POTASSIUM PHOS- 1% PHONATE SOLUTION POTASSIUM PHOS- 1% PHATE SOLUTION 4) POTASSIUM PHOS- 2% PHATE SOLUTION

CONTROL

*%INFECTION

100 0 10 0 30

PHYTOTOXICITY

0 0 0 0 0 0 WO 99/15017 PCT/US97/16997 EXAMPLE NO. 2 Shumard Oak/Powdery Mildew Fungicide Trial Trail Ridge Nursery, Keystone Hts., Florida In Example No. 2, the inventive compositions were tested for effectiveness against the powdery mildew (Phyllactinia corylea) that infects shumard oak (Quercus shumardii). In Example No. 2, an average of ten 3-gallon plots per experimental unit with 4 repetitions in a randomized complete block design were examined.

When only potassium phosphonate solution was applied, the percentage of infection increased to 40 percent, compared to a 20 percent infection in the control, indicating a pathological acerbation of the Ascomycete fungi. When the inventive composition including potassium phosphonate and potassium phosphate was applied, the infection was completely eliminated.

TABLEL2 TREATMENT RATE/100 gal. *%INFECTION 1) POTASSIUM PHOS- 1% 40 PHONATE SOLUTION 2) POTASSIUM PHOS- 1% 0 PHATE SOLUTION 3) POTASSIUM PHOS- 1% 0 PHONATE SOLUTION POTASSIUM PHOS- 1% PHATE SOLUTION 4) POTASSIUM PHOS- 2% 0 PHATE SOLUTION CONTROL -20

PHYTOTOXICITY

0 0 0 0 0 WO 99/15017 PCT/US97/16997 EXAMPLE NO. 3 Citrus Alternaria Fungicide Trial Kerr Center, Vero Beach, Florida In Example No. 3, the inventive composition was tested for effectiveness in citrus trees (Alternaria citri) that were infected with the fungi.

As used in Table No. 3 below, means percent young leaf drop, and means percent young fruit drop. and were determined by examining 4 terminals/tree with 4 repetitions in a randomized complete block design. The date on which the compositions were applied were March 21, 1996.

The compositions were rated on April 2, 1996. When only potassium phosphonate solutions were applied, and increased from 6.2 and 1.5 to 23.9 and 37.9, respectively, indicating pathological acerbation of the Ascomycete fungi.

Application of the inventive composition not only eliminated the acerbation, but showed an improvement in Y.L.D. and Y.F.D.

TABLE 3 TREATMENT RATE/100 gal. Y. F. D,

PHYTOTOXICITY

1) POTASSIUM PHOS- 0.5% 5.2 3.8 0 PHATE SOLUTION 2) POTASSIUM PHOS- 1 2.5 2.5 0 PHATE SOLUTION 3) POTASSIUM PHOS- 2 1.5 1.0 0 PHATE SOLUTION 4) POTASSIUM PHOS- 1 23.9 37.5 0 PHONATE SOLUTION POTASSIUM PHOS- 0.5% 2.2 3.7 0 WO 99/15017 PCT/US97/16997 PHATE SOLUTION POTASSIUM PHOS- PHONATE SOLUTION 6) CONTROL 6.2 1.5 0 EXAMPLE NO. 4 Carrot/Alternaria Fungicide Trial In Example No. 4, carrot plots were inoculated with Alternaria dauci fungi.

The plot sizes were single rows X 25 feet X 4 repetitions in a RCB design. The dates that compositions were applied were February 2, 9, 15, 22, and March 8, 14, 22, and 28, 1996. The fungi infections were rated on April 5 and April 23, 1996. The second rating was 25 days after the last fungicide application. The test took place at Sanford, Florida.

Application of the inventive solutions including potassium phosphonate and potassium phosphate improved the extent of infection from that otherwise occurring in the control carrots. Although the solution making use of only potassium phosphonate caused a slight improvement from the infection occurring in the control, it was substantially less than that associated with the inventive composition.

Also shown in Example No. 4 is a comparison of the effectiveness of the inventive composition to other fungicides, including Cu-Alexin and Fe-Alexin. This test demonstrates that the inventive composition is as effective as other well known fungicides, but without being as environmentally toxic.

WO 99/15017 PCT/US97/16997 TABLE 4 RATE/100 GAL,

TREATMENT

4/23/96 1) POTASSIUM PHOS- PHATE SOLUTION 2) POTASSIUM PHOS- PHONATE SOLUTION 3) POTASSIUM PHOS- PHATE SOLUTION POTASSIUM PHOS- PHONATE SOLUTION 4) Cu-ALEXIN Fe-ALEXIN 6)CONTROL AVG% DD =ON 4/5/96 18.7 28.8 10.7 0.5% 0.2 lb ai 0.2 lb ai 8.8 12.7 23.0 11.6 12.9 34.8 EXAMPLE NO. Citrus Preharvest Spray Trials Kerr Center, Vero Beach, Florida In Example No. 5, twenty-two fruits, each from five nova tangelo trees, were randomly selected and marked. The fruits were scuffed with an emery board and then sprayed with the compositions set forth below in Table 5, with five treatments on the same day. Seven days later, the fruit was picked and stored for two weeks in sealed white plastic bags, then examined for penicillium mold.

The degree of infection was rated using following scores: 0 no infection, 1 light infection (less than 30% coverage), 2 severe infection (100% coverage).

The degree of infection is the mean of scores from 22 fruit.

WO 99/15017 PCT/US97/16997 TABLE DEGREE OF INFECTION TREATMENT

PHYTOTOXICITY

1) POTASSIUM

PHOSPHONATE

SOLUTION

2) POTASSIUM

PHOSPHONATE

SOLUTION

3) POTASSIUM

PHOSPHATE

SOLUTION

4) POTASSIUM

PHOSPHATE

SOLUTION

POTASSIUM

PHOSPHONATE

SOLUTION

RATE

1% 2% 1% #ROTTEN FRUIT 1 0.91 0.5% 0.27 The above Examples demonstrate that the inventive compositions are useful in protecting plants against attack by both Phycomycete and Ascomycete with the application of one solution.

It will also be appreciated that compositions for controlling Phycomycete and Ascomycete fungi diseases in plants may also contain phosphate and phosphonate compounds comprising a fungicidally effective amount of at least a first salt having the following formula:

R

2 R-O-P-O- Me n

II

O

And a second salt having the following formula:

O

R, 0 P OH

I

R

1 0 P OH 0

I

R3 Where R, is selected from group consisting of H, K, an alkyl radical containing from I to 4 carbon atoms, halogen-substituted alkyl or nitro-substituted alkyl radical, an alkenyl, halogen-substituted alkenyl, alkinyl, halogen-substituted alkinyl, alkoxysubstituted alkyl radical, ammonium substituted by alkyl and hydroxy alkyl radicals;

R

2 and R 3 are selected from a group consisting of H and K; Me is selected from a group consisting of K, alkaline earth metal cations, aluminum atom; ammonium cation; and o...i n is a whole number from 1 to 3, equal to the valence of Me; and wherein at least one of RI and R3 in the second salt is K.

It will be appreciated that foliar applications of the inventive compositions will be effective as a common agricultural practice to control root pathogens caused by Phytophthoran, Phythium, and foliar infections caused by Plasmopara.

It will also be appreciated that the inventive compositions will have biocidal and arthropod pest control activity, and also have fertilizer effects, in plants. (Se e.g., U.S. Pat. Nos. 5,206,228, 5,133,891 and 5,514,200).

The disclosures in all references cited herein are incorporated by reference.

15 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.

It is to be understood that a reference herein to a prior art document does not constitute an admission that the document forms part of the common general knowledge in the art in Australia or in any other country.

U ftUU

U

U o ooo* 4 *f* 15A

Claims (23)

1. A fungicidal composition for controlling fungus disease in plants comprising: a fungicidally effective amount of at least a first salt selected from a group consisting ofK 2 HPO 3 KH2PO 3 and K 3 PO 3 and a second salt selected from a group consisting of K 2 HPO 4 KH 2 PO 4 and K 3 P0 4

2. The composition according to claim 1 wherein said composition comprises an aqueous solution, wherein each said first and second salt being present in solution from about 20 millimolar to about 5% vol./vol.

3. The composition according to claim 1 wherein the amount of said first said salt is one part by weight and the amount of said second salt is between 0.001 and 1,000 parts by weight.

4. A method of controlling fungus disease in plants comprising: applying to the plants in fungicidally effective amounts at least a first salt selected Sfrom a group consisting of K 2 HPO 3 KH 2 PO3 and K 3 P0 3 and a second salt selected from a group consisting of K 2 HPO 4 KH 2 PO 4 and K 3 P0 4

5. The method according to claim 4 wherein said composition comprises an aqueous solution, wherein each said first and second salt being present in solution from about 20 millimolar to about 5% vol./vol.

6. The method according to claim 4 wherein the amount of said first Ssaid salt is one part by weight and the amount of said second salt is between 0.001 and 1,000 parts by weight.

7. A fungicidal composition for controlling fungus in plants comprising: a fungicidally effective amount of at least a first salt having the following formula: R 2 R P O Men+ II O n And a second salt having the following formula: 16 O I R 1 0 P OH O R 3 Where R, is selected from group consisting of H, K, an alkyl radical containing from 1 to 4 carbon atoms, halogen-substituted alkyl or nitro-substituted alkyl radical, an alkenyl, halogen-substituted alkenyl, alkinyl, halogen-substituted alkinyl, alkoxy- substituted alkyl radical, ammonium substituted by alkyl or hydroxy alkyl radicals; R 2 and R 3 are selected from a group consisting of H and K; Me is selected from a group consisting of K, alkaline earth metal cations, or aluminum atom; ammonium cation; and n is a whole number from 1 to 3, equal to the valence of Me; and wherein at least one of R and R 3 in the second salt is K.

8. The composition according to claim 7 wherein said composition comprises an aqueous solution, wherein each said first and second salt being present in solution from about 20 millimolar to about 5% vol./vol.

9. The composition according to claim 7 wherein the amount of said first said salt is one part by weight and the amount of said second salt is between 0.001 and 1,000 parts by weight.

10. A method of controlling fungus disease in plants comprising applying to the plants in enhanced fungicidally effective amounts a composition comprising: an aqueous solution of H 3 PO 3 and KOH, and an aqueous solution of monopotassium phosphate and KOH.

11. The method of claim 10 wherein the amount of potassium phosphonate in said aqueous solution and the amount of potassium phosphate in said aqueous solution is each present in said composition in an amount from about 20 millimolar to about 5% vol./vol. 17

12. The method of claim 10 wherein the amount of potassium phosphonate prepared from solution in said composition is one part by weight and the amount of potassium phosphate prepared from solution in said composition is between 0.001 and 1,000 parts by weight.

13. A method of controlling fungus disease in plants comprising applying to the plants in enhanced fungicidally effective amounts a composition prepared by mixing: an aqueous solution of H 3 P0 3 and KOH, and an aqueous solution ofmonopotassium phosphate and KOH.

14. The method of claim 13 wherein the amount of potassium phosphonate in said aqueous solution and the amount of potassium phosphate in said aqueous solution is each present in said composition in an amount from about 20 millimolar to about 5% vol./vol.

The method of claim 13 wherein the amount of potassium phosphonate prepared from solution in said composition is one part by weight and the amount of potassium phosphate prepared from solution in said composition is between 0.001 and 1,000 parts by weight.

16. A method of controlling fungus disease in plants comprising applying to the plants in enhanced fungicidally effective amounts a composition comprising: an aqueous solution of H 3 PO 3 and KOH, and an aqueous solution of dipotassium phosphate.

17. The method of claim 16 wherein the amount of potassium phosphonate in said aqueous solution and the amount of dipotassium phosphate in said aqueous solution is each present in said composition in an amount from about 20 millimolar to about 5% vol./vol.

18. The method of claim 16 wherein the amount of potassium phosphonate prepared from solution in said composition is one part by weight and the amount of dipotassium phosphate prepared from solution in said composition is between 0.001 and 1,000 parts by weight.

19. A method of controlling fungus disease in plants comprising applying to the plants in enhanced fungicidally effective amounts a composition prepared by mixing: -18- an aqueous solution of H 3 PO 3 and KOH, and an aqueous solution of dipotassium phosphate.

The method of claim 19 wherein the amount of potassium phosphonate in said aqueous solution and the amount of dipotassium phosphate in said aqueous solution is each present in said composition in an amount from about 20 millimolar to about 5% vol./vol.

21. The method of claim 19 wherein the amount of potassium phosphonate prepared from solution in said composition is one part by weight and the amount of dipotassium phosphate prepared from solution in said composition is between 0.001 and 1,000 parts by weight.

22. A fungicidal composition for controlling fungus disease in plants comprising a fungicidal effective amount of a phosphonate salt and a phosphate salt substantially as herein described with reference to any one of the Examples.

23. A method of controlling fungus disease in plants comprising i.i 15 applying to the plants in fungicidally effective amounts the fungicidal composition of claim 22. *Dated this 5th day of October 2001 FOLIAR NUTRIENTS, INC. By their Patent Attorneys GRIFFITH HACK 9 9 o• o* 9* 19