the present invention relates to compositions and methods for use in preventing diseases , such as late blight , caused by the genus phytophthora . in particular , the present invention relates to compositions and methods for use in preventing plant diseases caused by phytophthora infestans . the composition is comprised of a phosphate ( po 4 ) constituent and phosphonate ( po 3 ) constituent , with it most preferred that a composition comprised of potassium phosphonate and potassium phosphate be used . once the composition is formed , it can be applied to plants to prevent infection by phytophthora infestans and manifestations related to the infection . the composition can be applied as either a dry mix or an aqueous solution to plants prior to infection by the phytophthora infestans organism . the composition for preventing phytophthora infestans is prepared by combining phosphonate and phosphate constituents . any of a variety of phosphates are suitable for use , including k 2 hpo 4 , k 3 po 4 , kh 2 po 4 , ( nh 3 ) 2 hpo 4 , ( nh 3 ) h 2 po 4 , and combinations thereof . the phosphonates , like the phosphates , can be selected from any of a variety of compositions , including k 2 hpo 3 , k 2 po 3 , kh 2 po 3 ( nh 3 ) 2 hpo 3 , ( nh 3 ) h 2 po 3 , and combinations thereof . any phosphate and phosphonate constituent combination can be used as long as infection by and manifestation of phytophthora infestations is inhibited . additionally , it is necessary for the constituents to have suitable solubility in a carrier and to be of a constitution to allow easy distribution in an area where plants to be treated are grown . more preferably , the phosphonate and phosphate constituents , when combined , will have a synergistic effect in inhibiting phytophthora infestans . the most preferred phosphate ( po 4 ) and phosphonate ( po 3 ) constituents for use in preventing phytophthora infestans infection are combinations of k 2 hpo 3 and k 2 hpo 4 . as such , the phosphate ( po 4 ) and phosphonate ( po 3 ) constituents are combined to form the composition used to prevent phytophthora infestans infection . while the discussed constituents are preferred for use in treating plants and preventing infection by the phytophthora organism , variations of the phosphate and phosphonate constituents can be used . as such , it is preferred if the compound comprises a fungicidally effective amount of at least a first salt having the following formula : where r 1 is selected from the 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 , alkynl , halogen - substituted alkynl , alkoxy - substituted 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 , and the ammonium cation ; and n is a whole number from 1 to 3 , equal to the valence of me . the constituents should be preferably mixed with a suitable carrier to facilitate distribution to an area where the plants to be treated are grown . the carrier should be agriculturally acceptable , with water ( h 2 o ) most preferred . as an example of how to form the composition , it is preferred to first form a potassium phosphonate aqueous solution , with the phosphonate formation as follows : h 3 po 3 is produced by the hydrolysis of phosphorus trichloride according to the reaction : pcl 3 + 3h 2 o & gt ; h 3 po 3 + 3hcl . the hcl 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 : h 3 po 3 + koh & gt ; kh 2 po 3 + h 2 o to about ph 6 . 5 , and to produce a 0 - 22 - 20 liquid weighing 11 . 15 lbs ./ gal . this solution is commercially available and is sold under the trademark “ phos - might ” by foliar nutrients , inc ., cairo , ga . 31728 . the phosphate ( po 4 ) is produced by reacting mono potassium phosphate ( 0 - 51 . 5 - 34 ) with 45 % potassium hydroxide in aqueous solution to produce dipotassium phosphate , by the following reaction : kh 2 po 4 + koh & gt ; k 2 hpo 4 + h 2 o with a product density of 1 . 394 at 20 ° c . and a solution ph of 7 . 6 producing a 0 - 18 - 20 analysis . this solution is commercially available and is sold under trademark “ k - phos ” by foliar nutrients , inc ., cairo , ga . 31724 . after the potassium phosphonate and potassium phosphate constituents , or other phosphonate and phosphate constituents , are formed , they can be combined to produce the potassium phosphonate and potassium phosphate composition . this composition is used to then treat plants for the prevention of infection by the phytophthora genus , especially phytophthora infestans . varying amounts of each compound , for example , k 2 hpo 3 , kh 2 po 3 , k 2 hpo 4 , or kh 2 po 4 in an aqueous solution , are combined at rates ranging from 20 millimole to 5 % vol ./ vol ., depending on crop host and the pathogen complex and level of infection . alternatively , the amount of the first salt is equal to one part by weight and the amount of the second salt is equal to between 0 . 001 and 1 , 000 parts by weight . it is preferred if the composition is comprised of 21 . 7 % k 2 hpo 4 and 21 . 5 % k 2 hpo 3 or 11 . 8 % po 4 − 3 and 10 . 7 % po3 − 2 , all of which are soluble . once formed , the composition will be applied to various plants to prevent phytophthora infestans infection . 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 example , could also be efficacious depending on specific crops and pathogens . while it is preferred to apply the composition in an aqueous solution , other forms of application may be used , including dusts , flowables , water dispersable granules , granules and inert emulsions , as well as oils . at least one application should be made ; however , multiple applications of the composition can be made . the inventive composition has utility on fruit crops , agronomic crops , ornamentals , trees , grasses , vegetables , grains , and floricultural crops , as well as some aquatic crops , including water cress . the crops most likely infected by phytophthora infestans are potatoes ( solanum tuberosum ) and tomatoes ( lycopersicon esculentum ). as such , the present composition is especially useful in treating potato and tomato plants to prevent phytophthora infection . the following examples set forth the preferred concentrations and techniques for formulation thereof , as well as methods of application , use and test results demonstrating the efficacy of the inventive concentration in protecting plants against attack by phytophthora infestans . 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 . in each of examples 1 and 2 , 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 ( crb ) design replicated four times . as used in the examples , “ percent late blight ” means the percent of plants that exhibit blight . “ lesions per plant ” relate to the number of lesions on a particular plant caused by the infectious inoculum . the “ no . infected leaflets ” relates to the number of infected leaves per plant . potatoes ( solanum tuberosum , variation atlantic ) were infected with a pathogen , phytophthora infestans , to determine whether suitable treatments could be developed to eliminate the pathogen from the infected plants and , more importantly , prevent infection of the plants by the pathogen . the phytophthora pathogen causes late blight in infected plants . the plants were treated with the below listed compositions , twice , with the applications being seven ( 7 ) days apart . the composition of the inoculant added to the plants is listed below in the table . one week ( 7 days ) after the last inoculation was made to the plants , the potato plants were then infected with the pathogen , phytophthora infestans . the infectious inoculum was equal to 12 , 000 sporangia per millimeter ( ml ), with 20 ml administered per plant . the genotype of the pathogen was us - 8 and the matingtype was a2 . seven days after inoculation with the pathogen , the results were tabulated to determine the percentage of blight in the plants and the number of lesions per plant . additionally , the number of infected leaflets per plant were tabulated . the results are as follows : summary late blight observations fnx greenhouse experiment no . infected % late lesions leaflets treatment rate / a blight per plant per plant k 2 hpo 3 + 1 % + 0 . 39 0 . 5 0 . 5 k 2 hpo 4 1 % cu - eddha 0 . 2 lb . ai 12 . 30 35 . 3 26 . 9 k 2 hpo 3 1 % 1 . 85 2 . 4 1 . 8 k 2 hpo 4 1 % 18 . 45 41 . 4 31 . 1 control 28 . 12 84 . 4 50 . 1 as can be seen , an inoculum of just phosphonate ( po 3 ) showed good results in controlling the blight . however , better results were achieved using the phosphate ( po 4 ) and phosphonate ( po 3 ) composition . the ( po 4 ) and ( po 3 ) combination demonstrated exceptional blight depression , indicating that potato blight can be better controlled using a composition comprised of ( po 3 ) and ( po 4 ). this indicates that a synergistic effect is achieved with a ( po 3 ) and ( po 4 ) combination . tomatoes ( lycopersicon esculentum , fl 40 ) were infected with a pathogen , phytophthora infestans , to determine whether suitable treatments could be developed to prevent infection of the plants by the pathogen . the phytophthora pathogen causes late blight in infected plants . the plants were treated with the below listed compositions , twice , with the application dates being seven ( 7 ) days apart . the composition of the inoculant added to the plants is listed below in the table . one week ( 7 days ) after last inoculation was made to the plants , the tomato plants were then infected with the pathogen , phytophthora infestans . the infectious inoculum was equal to 12 , 000 sporangia per millimeter ( ml ), with 20 ml administered per plant . the genotype of the pathogen was us - 17 and the matingtype was a1 . seven days after inoculation with the pathogen , the results were tabulated to determine the percentage of blight in the plants and the number of lesions per plant . additionally , the number of infected leaflets per plant were tabulated . the results are as follows : greenhouse tomato late blight trial no . infected treatment rate / a lesions / plant leaflets / plant k 2 hpo 3 + 2 % 6 . 0 2 . 5 k 2 hpo 4 simazine 4l 0 . 1 lb . ai 52 . 3 36 . 8 k 2 hpo 3 1 % 56 . 7 21 . 5 k 2 hpo 4 1 % 74 . 8 36 . 5 control 66 . 8 33 . 8 excellent results were achieved using the phosphate ( po 4 ) and phosphonate ( po 3 ) composition . the ( po 4 ) and ( po 3 ) combination demonstrated exceptional blight depression , indicating that the blight can be better controlled using a composition comprised of ( po 3 ) and ( po 4 ). this indicates that a synergistic effect is achieved with a ( po 3 ) and ( po 4 ) combination . the above examples demonstrate that the inventive compositions are useful in protecting plants against attack by the phytophthora infestans infection with the application of one solution . the disclosures in all references cited herein are incorporated by reference . alternatively , the composition can be used to prevent infection by phycomycetes , ascomycetes , and other fungal pathogens , as well as bacteria . thus , there has been shown and described a method relating to the use of a phosphonate ( po 3 ) and phosphate ( po 4 ) composition which provides improved efficacy in controlling phytophthora infections in plants which fulfills all the objects and advantages sought therefore . it is apparent to those skilled in the art , however , that many changes , variations , modifications , and other uses and applications for a phosphonate ( po 3 ) and phosphate ( po 4 ) composition are possible , and also such changes , variations , modifications , and other uses and applications of a phosphonate ( po 3 ) and phosphate ( po 4 ) composition which do not depart from the spirit and scope of the invention are deemed to be covered by the invention , which is limited only by the claims which follow .