Abstract:
This invention relates to novel compositions containing a compound of formula I ##STR1## with a chelating agent capable of tying up essentially all of the calcium ion in aqueous spray water solution. These compositions are useful as plant growth regulants.

Description:
BACKGROUND OF THE INVENTION 
     It is well known that compounds of formula I are useful as growth regulants. ##STR2## wherein R 1  is alkyl of 1 to 3 carbon atoms or allyl; and M is ammonium, sodium, lithium or potassium. 
     For instance, the compounds of formula I and their utility as growth regulants are taught in U.S. Pat. No. 3,846,512, along with many related compounds. 
     It has been found that spray solutions of compounds of formula I which have been prepared in hard water have lower activity than spray solutions prepared in soft water. By hard water, it is meant generally water containing calcium and optionally magnesium ions in excess of 100 ppm hardness calculated as CaCO 3 . At 100 ppm hardness the effect is small. However, with increasing hardness it becomes more noticable. Many natural waters have greater hardness and significantly reduce the activity of compounds of formula I. Thus, a means for enhancing the effectiveness of the compounds of formula I in hard water is needed. 
     SUMMARY OF THE INVENTION 
     According to the instant invention, it has unexpectedly been discovered that if a chelating agent capable of tieing up virtually all of the calcium ions in an aqueous spray water solution is added to solutions containing compounds of formula I, the growth regulant activity of the compounds is enhanced. 
     The chelating agent to be added should be added in at least a stoichiometric amount for best results. Specific chelating agents included in the instant invention are nitrilotriacetic acid and its alkali or ammonium salts, gluconic acid and its alkali or ammonium salts, citric acid and its alkali or ammonium salts, and ethylenediaminetetraacetic acid and its alkali or ammonium salts. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In more detail, the preferred compounds of formula I are as follows: ##STR3## 
     Included in the preferred chelating agents which are added to the spray solution are the alkali metal gluconate salts and the alkali metal citrate salts. The acids of both salts are also preferred. Especially preferred are the sodium gluconate salts and the sodium citrate salts. The ammonium salts of both are also especially preferred, as are ethylenediaminetetraacetic acid and nitrilotriacetic acid and their alkali or ammonium salts. 
     The amount of chelating agent may range from about stoichiometric to an excess based on the total hardness of the water being used. There is no real upper limit to the amount of chelating agent except practicality and cost. It is rarely reasonable to use more than a 100% excess, however. It is also within the scope of this invention to add less than a stoichiometric amount of chelating agent if desired. For instance, there may be instances where one may wish to tie up only a portion of the calcium ions present. Because chelating agents generally complex magnesium ions, the other major component of water hardness, as well as other hardness producing ions such as iron and manganese which are very minor components of natural water, the total hardness rather than just calcium ion concentration, should be used in calculating the amount of chelating agent to be used. Total hardness can easily be determined by titration with EDTA. See Method 122B in &#34;Standard Methods for the Examination of Water and Waste Water&#34;, 13 Ed., American Public Health Assoc., N.Y., 1971 (p. 179 ff.), which is incorporated by reference. There is generally no need to add chelating agent when the water hardness is less than about 1.0×10 -3  molar, and waters rarely exceed 7×10 -3  molar total hardness, so the usual range of concentration of chelating agent will fall between 1.0 and 14×10 -3  equivalents per liter of water used to make the spray solution. 
     Perusal of &#34;Stability Constants of Metal-Ion Complexes&#34;, Special Publication 17, The Chemical Society, Burlington House W.1, London, 1964, will show many chelating agents for calcium. Chelating agents having a Kml or β on the order of 10 +3  or more are likely to be useful. Where ##EQU1## using the same terminology. Those skilled in the art will also realize that pH and the actual concentrations of ions play a part in determining the efficiency of chelating agents. At normal use levels, the sprays of carbamoyl phosphonates of structure I will range from about pH 5.5 to 8.5. The ammonium salt will generally yield a pH of from 5.5 to 7.0; the others will be more sensitive to the pH of the spray waters. Because chelating agents are more efficient at increased pH, the salt forms of chelating agents are more useful than the free acid forms. It should be understood that the chelating agent acts while the spray is evaporating on the leaves of plants when the concentration of all solutes may be 10 or more times the original concentration. These facts, together with the possibility that a competition for calcium ions exists between carbamoyl phosphonate and chelating agent implies that the chelating agent used need not be exceptionally powerful. 
     UTILITY 
     As mentioned previously, the compounds of formula I are plant growth retardants that are effective in many situations, it has been determined that their efficacy is reduced when they are applied in hard water. 
     The utility of the present invention was discovered in a greenhouse test (Table 1). 
     The results in Table 1 are expressed as plant response ratings, which consist of a number and a letter. The number describes the extent of the response and ranges from zero to ten, with zero representing no response and ten representing 100% response. The letter describes the type of response, with &#34;G&#34; representing growth retardation. 
     In reviewing Table 1, a comparison between the plant responses to applications in deionized water and in hard water reveals that hard water reduces the efficacy of ammonium ethyl (aminocarbonyl) phosphonate. The results also demonstrate that the compositions of the present invention are useful in overcoming the negative effects of hard water on the efficacy of ammonium ethyl (aminocarbonyl) phosphonate. With Black Valentine bean and privet, applications in hard water containing ethylenediaminetetraacetic acid, gluconic acid and citric acid were more effective than in hard water alone. With willow and forsythia, applications in hard water containing ethylenediaminetetraacetic acid, nitrilotriactic acid, gluconic acid and citric acid were more effective than in hard water alone. Applications in hard water containing nitrilotriacetic acid and gluconic acid were more effective than applications in hard water alone on apple. 
     
                       Table 1______________________________________Test samples of ammonium ethyl (aminocarbonyl)phospho-nate were applied as overall sprays on several plant -species (3replicates) at the rate of 1 kg/ha in vari-ous solvents which are mentioned below. Plant responseratings were taken 1, 5 and 9 weeks after application.             Black Valentine Bean*Treatment           1 wk.   5 wks.  9 wks.______________________________________Deionized water     6G      6GHard water (350 ppm CaCO.sub.3 basis,               2G      4G3.5×10.sup.-3 M).sup.+Hard water containing 1490 ppm               4G      5Gethylenediaminetetraaceticacid . 2H.sub.2 O (4×10.sup.-3 M).sup.+Hard water containing 765 ppm               2G      4Gnitrilotriacetic acid(4×10.sup.-3 M).sup.+Hard water containing 1570 ppm               5G      6Ggluconic acid (8×10.sup.-3 M).sup.+Hard water containing 841 ppm               5G      6Gcitric acid (4×10.sup.-3 M).sup.+             Willow Salix sp.Treatment           1 wk.   5 wks.  9 wks.Deionized water     0       5G      3GHard water (350 ppm CaCO.sub.3 basis,               0       1G      1G3.5× 10.sup.-3 M).sup.+Hard water containing 1490 ppm               0       3G      5Gethylenediaminetetraaceticacid . 2H.sub.2 O (4×10.sup.-3 M).sup.+Hard water containing 765 ppm               0       3G      2Gnitrilotriacetic acid(4×10.sup.-3 M).sup.+Hard water containing 1570 ppm               0       6G      5Ggluconic acid (8×10.sup.-3 M.sup.+Hard water containing 841 ppm               0       4G      3Gcitric acid (4×10.sup.-3 M).sup.+             Forsythia Forsythia sp.Treatment           1 wk.   5 wks.  9 wks.______________________________________Deionized water     0       9G      8GHard water (350 ppm CaCO.sub.3 basis,               0       6G      3G3.5×10.sup.-3 M).sup.+Hard water containing 1490 ppm               0       9G      9Gethylenediaminetetraaceticacid . 2H.sub.2 O (4×10.sup.-3 M).sup.+Hard water containing 765 ppm               0       8G      6Gnitrilotriacetic acid(4×10.sup.-3 M).sup.+Hard water containing 1570 ppm               0       9G      8Ggluconic acid (8×10.sup.-3 M).sup.+Hard water containing 841 ppm               0       9G      6Gcitric acid (4×10.sup.-3 M).sup.+             Privet Liqustrum  Sp.*Treatment           1 wk.   5 wks.  9 wks.______________________________________Deionized water     0       0       6GHard water (350 ppm CaCO.sub.3 basis,               0       0       3G3.5×10.sup.-3 M).sup.+Hard water containing 1490 ppm               0       0       4Gethylenediaminetetraaceticacid . 2H.sub.2 O (4×10.sup.-3 M).sup.+Hard water containing 765 ppm               0       0       1Gnitrilotriacetic acid(4×10.sup.-3 M).sup.+Hard water containing 1570 ppm               0       0       9Ggluconic acid (8×10.sup.-3 M).sup.+Hard water containing 841 ppm               0       0       4Gcitric acid (4×10.sup.-3 M).sup.+             Apple Malus sp.Treatment           1 wk.   5 wks.  9 wks.______________________________________Deionized water     0       2G      1GHard water (350 ppm CaCO.sub.3 basis,               0       0       03.5×10.sup.-3 M).sup.+Hard water containing 1490 ppm               0       2G      0ethylenediminetetraaceticacid . 2H.sub.2 O (4×10.sup.-3 M).sup.+Hard water containing 765 ppm               0       2G      1Gnitrilotriacetic acid(4×10.sup.-3 M).sup.+Hard water containing 1570 ppm               0       2G      2Ggluconic acid (8×10.sup.-3 M).sup.+Hard water containing 841 ppm               0       1G      0citric acid (4×10.sup.-3 M).sup.+______________________________________ *Bean plants were discarded after 5 weeks. Privet grew slowly and was not rated for retardation effects until 9 weeks after application. No woody plants were rated for growth retardation 1 week after application. .sup.+ Note the acids had been preneutralized to ca. pH 5.5 with ammonia before making the combinations. 
    
     EXAMPLE 2 
     A natural water of 149 ppm hardness in Maryland was spiked with calcium chloride to produce 549 ppm hardness as CaCO 3  (equivalent to 5.5×10 -3  m as Ca ++ ) for a hard water control. To a portion of the hard water, 14×10 -3  m gluconate was added in the form of ammonium gluconate (i.e., 27% excess over the stoichiometric amount). To both waters ammonium ethyl carbamoylphosphonate was added to produce a concentration of 4 pounds per 100 gallons (4.8 g/l). The sprays were applied to a mixed population of sweet gum, silver poplar, red oak and red maple ranging from about 3-10 feet (1-3 meters) in height at an active rate of 4 pounds per acre (4.48 kg/ha) in early October. The plots were evaluated the following June with the tabulated results. 
     
         ______________________________________                   Hard Water      Hard Water   &amp; Gluconate______________________________________Sweet Gum    About 50% re-  Nearly complete        foliation      suppression of                       regrowthRed Oak      More than 50%  Little or no        refoliation    refoliationRed Maple    More than 50%  Some sprouting;        refoliation    no refoliationSilver Poplar        More than 50%  More than 50%        refoliation    refoliation______________________________________ 
    
     Note that silver poplar remains resistant to the carbamoylphosphonate whether or not chelating agent was added. With the other species, dramatic improvements in activity were noted.