Patent Publication Number: US-5834403-A

Title: Low rate application of inhibitors of ethylene biosynthesis or action

Description:
This application claims the benefit of U.S. Provisional Application Number 60/009,050 filed on Dec. 21, 1995. 
     NOTICE OF COPENDING PATENT APPLICATIONS 
     The following patent applications are copending in the United States Patent and Trademark Office with this application: 
     1. Plant Growth Retardants In Combination With Inhibitors Of Ethylene Biosynthesis Or Action, U.S. patent application Ser. No. 08/770,492, filed on Dec. 20, 1996, and incorporated herein by reference; 
     2. Encapsulated Plant Growth Regulator Formulations, U.S. patent application Ser. No. 08/771,319, filed on Dec. 20, 1996 and incorporated herein by reference; 
     3. Encapsulated Plant Growth Regulator Formulations And Applications, U.S. patent application Ser. No. 08/771,734, filed on Dec. 20, 1996 and incorporated herein by reference; 
     4. Encapsulated Plant Growth Regulator Formulations In Combination With Plant Growth Retardants, U.S. patent application Ser. No. 08/771,769, filed on Dec. 20, 1996 and incorporated herein by reference; 
     5. Plant Growth Regulators In Pyrrolidone Solvents, U.S. patent application Ser. No. 08/771,768, filed on Dec. 20, 1996 and incorporated herein by reference; 
     6. Enhancing The Rate of Seed Germination With Application of Ethylene Biosynthesis Inhibitors, U.S. patent application Ser. No. 08/770,789, filed on Dec. 20, 1996 and incorporated herein by reference; and 
     7. Aminoethoxyvinylglycine in combination with a Plant Growth Regulator, U.S. patent application Ser. No. 08/777,716, filed on Dec. 20, 1996 and incorporated herein by reference. 
     APPLICATIONS IN FIELD OF THE INVENTION 
     The present invention is related generally to the field of agriculture and specifically to compositions and use of plant growth regulators. 
     BACKGROUND OF THE INVENTION 
     Agriculture workers actively seek ways to improve the economic output of commercial crops. For example, in cotton crops, workers seek to improve such growth factors as increased boll set, increased floral initiation, decreased floral abscission, decreased boll abscission, and enhanced root growth. Workers also seek to increase plant tolerance to environmental stress. 
     Formulations containing plant growth regulators (PGRs) have been developed to improve the economic yield of agricultural plants. Plant growth retardants and inhibitors of ethylene biosynthesis or action are two types of PGRs. Some plant growth retardants have been shown to inhibit gibberellin biosynthesis resulting in the reduction of shoot height in small grains and cotton. This reduction in shoot height has a strong economic benefit since it provides for less lodging in small grains and reduction of excessive vegetative growth. It also provides more uniform ripening in cotton. 
     Three groups of gibberellin biosynthesis inhibitors are known. The first group encompasses compounds with quaternary ammonium, phosphonium or sulphonium moieties. One example of a compound from this group is mepiquat chloride, described in U.S. Pat. No. 3,905,798 and incorporated herein by reference. Mepiquat chloride may increase cotton yields, boll load, lint yield and seed yield. Mepiquat chloride is also known to reduce vegetative growth, plant height and boll rot. Mepiquat chloride also induces early uniform ripeness if the plants are treated early during their development. Chloromequat chloride is also a representative compound of this group. 
     The second group of plant growth retardants encompasses compounds with a nitrogen containing heterocycle such as flurprimidol, paclobutrazol, uniconazole and ancymidol. 
     The third group encompasses acylcycicohexanediones (such as trinexapac-ethyl and prohexadione-Ca) and daminozide. 
     It is known that ethylene is involved in plant senescence and plant stress reactions. Ethylene is also involved in leaf, flower, and fruit abscission. Hence, agents that inhibit or regulate the production of ethylene or control its action in plants have been developed in an effort to improve the yield of agricultural crops. Inhibitors of ethylene biosynthesis include substituted oxime-ethers as described in U.S. Pat. No. 4,744,811, incorporated herein by reference. These compounds are also described in PCT Application WO 95-02211, incorporated herein by reference, as being soil amendment compositions that increase the assimilation of nitrogen by higher plants. 
     Other inhibitors of ethylene biosynthesis or action include aminoethoxyvinylglycine (&#34;AVG&#34;), aminooxyacetic acid (&#34;AOA&#34;), rhizobitoxine, and methoxyvinyl glycine (&#34;MVG&#34;). Silver ions (e.g. silver thiosulfate), and 2,5-NORBORNADIENE inhibit ethylene action. 
     Plant growth regulators have also been used to protect crops from the effects of environmental stress. Gianfagna, T. J. et al &#34;Mode of Action and Use of Growth Retardants in Reducing the Effects of Environmental Stress on Horticultural Crops: Karssen C. N. et al. (eds.) Progress in Plant Growth Regulation, pp. 778-87 (1992). For example, researchers found that if ethephon was applied at a low rate (0.08 mM) it significantly delayed bloom in peach and reduced side effects. Researchers also found that ethephon increased the yields and hardiness of several horticultural plants. 
     Although PGRs have been developed as a means to improve agricultural crop yields, certain obstacles make the actual use of the PGR prohibitive. For example, many of the compounds display phytotoxicity. Other compounds are difficult to synthesize. 
     Many compounds require high rate applications to be effective. For example, PCT Application WO 93/07747, incorporated herein by reference, describes an improvement in a plant growth factor by applying aminoethoxyvinylglycine (&#34;AVG&#34;), an inhibitor of ethylene biosynthesis, to cotton plants. As the rate of AVG treatment increased, so did the improvement. (WO 93/07747, Examples 2-4). Assuming that a spray volume of 500 l/ha was used, the rates of application described in WO 93/07747 would be approximately 62.5 to 500 g ai/ha (ai=active ingredient). The maximum rate response occurs at the highest rates. 
     High rate applications may result in a significant waste of material and may result in the discharge of the PGRs into the surrounding environment. Also, although many of these compounds may induce a beneficial growth habit, they do not provide consistent improvement in plant growth factors. Other compounds may lose their effectiveness or cause a reduction in yield when applied to species which are under some form of environmental stress. 
     Thus, it is an object of the invention to formulate a PGR that not only improves a plant growth factor but one that also reduces toxicity. It is also an object of the present invention to provide a PGR that has lower application rates and has limited environmental impact. 
     SUMMARY OF THE INVENTION 
     Provided herein is a method for improving at least one growth factor in a plant comprising applying an inhibitor of ethylene biosynthesis or action to the plant at a low rate. An improvement in a plant growth factor is defined as an agronomic improvement of plant growth such as increased floral (square) initiation, increased flower retention, increased fruit retention, increased square retention, increased boll retention, increased root growth, decreased internode length, increased stress tolerance, decreased wilting, decreased senescence, darker green pigmentation, increased germination rate, increased tolerance to low and high temperatures, and increased crop yield. That is, a favorable alteration of the physiology or growth of plants or an increase or decrease in plant growth which leads to an economic or agronomic benefit. Improvement in growth factors that result from the inhibition of ethylene production is preferred. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It has been surprisingly found that a low rate application of a substituted oxime-ether, having the formula: ##STR2## where R1 and R2 independently of one another are C1-C6-akyl, n is 2 or 3 and R3 is hydrogen or C1-C6 akyl improves at least one plant growth factor on a consistent basis. 
     Other compounds of the present invention provide an improvement in at least one plant growth factor. Examples of other compounds that may be used include  (isopropylidene)-amino!oxy acetic acid represented by the structure: ##STR3## Another example of a compound that may used in the present invention is aminooxyacetic (&#34;AOA&#34;) acid represented by the following structure: ##STR4## Preferred oxime-ethers for use in the method include the following compounds: 
     1) { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester represented by the structure: ##STR5## 2) { (isopropylidene)-amino!oxy}-acetic acid-2-(hexyloxy)-2-oxoethyl ester represented by the structure: ##STR6## and 3) {{cyclohexylidene)-amino!oxy}-acetic acid-2-(isopropyloxy)-2-oxoethyl ester represented by the structure: ##STR7## 
     The most preferred compound for carrying out the present invention comprises { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester. 
     Low rate application is defined as a single application rate lower than about 50 g ai/ha (grams of active ingredient per hectare). An effective number of low rate applications can be made throughout the growing season. Preferably, the low rate application is performed from one to about ten times during the growing season, most preferably from one to about four times during the growing season. Preferred embodiments of the present invention comprise single application rates ranging from about 100 mg ai/ha to about 50 g ai/ha applied from one to four times during a growing season and ranging from about 500 mg ai/ha to about 10 g ai/ha applied from one to four times during a growing season. Other rates useful for carrying-out the invention include a rate of less than or equal to about 2 g ai/ha and down to about 100 mg ai/ha applied from one to four times during a growing season. The most preferred single application rate is about 500 mg/ha to about 1.5 g ai/ha applied from one to four times during a growing season. 
     The present invention finds its best results in horticultural and agricultural plants and crops. The invention provides most consistent improvement of at least one plant growth factor in the following plants: cotton, soybean, peanut, pepper, tomato, wheat, barley, rice plant, apple, citrus, grape and corn canola. Improvement is also found in turf. 
     Preferred formulations of the low rate application include those formulations that provide an ethylene inhibitor in an effective amount to obtain consistent improvement in a plant growth factor, that is, those formulations that provide statistically significant improvement (e.g., where P=0.15 or less) when compared to untreated plants wherein the improvement is obtained more than about 50% of the time, preferably more than 60% of the time, more preferably more than 75% of the time and most preferably more than 90% of the time. In a preferred embodiment of the invention, the improvement of the plant growth factor ranges from about 4% to about 60% over the untreated plants or over those plants treated with mepiquat chloride. 
     Tests carried out at 50 g ai/ha and above provided inconsistent results. 
     Accordingly, the present invention provides surprising and unexpected results since it obtains superior results at low rates. 
     The formulations described in this invention are generally applied to the foliage prior to bud and flower development but they can also be applied to the foliage, buds, flowers, or fruits beginning at early bud development (e.g., matchhead square in cotton) in one to four sequential applications. If sequential applications are used, applications are preferably timed at approximately 10 to 14 days apart. When applied by spraying, the active ingredient is generally mixed with water as a carrier solution in a dilution sufficient to cover the area. Typically the spray volume of the aqueous treatment solution would be about 150 to 500 l/ha for arable crops and up to about 1,500 l/ha for fruit trees. Soil drenching is another method of application that is useful when practicing the invention. 
     Hence, the present invention provides a method which improves the economic or agronomic output of agricultural crops and decreases the amount of material that needs to be used to obtain improvement in a plant growth factor. 
     The following examples are illustrative only and are not meant to limit the invention in any manner. 
     EXPERIMENTS 
     1. Cotton trials. Field tests with Cotton plants were conducted as follows: Cotton plots were laid out about four to six rows wide and 30 to 40 feet long. In two trials, the center two rows of each four row plot were sprayed over the foliage, buds, blooms, and fruits with the respective applications and the outer two rows were not treated in order to provide a buffer row between plots. In remaining trials, all rows were sprayed over the foliage, buds, blooms, and fruits, but only the center two rows harvested. In most experiments each treatment was replicated four times and organized in randomized complete block design. 
     The first treatments were applied when the flower buds (i.e., &#34;squares&#34;) reached the size of a &#34;match-head&#34;, i.e. when the first square of a typical cotton plant was about the size of a matchhead, and when 50% of the plants had one or more matchhead squares. Generally, the formulations, except for the mepiquat chloride, were applied at 1, 10, 20, 50 and 100 g ai/ha. The amount of formulated material to be applied to each treatment was calculated on the basis of the amount of the area to be treated with each rate. For example, a treatment applied at a rate of 1 g of the active ingredient required four applications of 0.022 g ai/ha when four plots (2133 square feet) were treated. Thus, 0.022 g of active material was mixed with one liter of water or the amount of water necessary for the treated area for the spray volume to be equivalent to about 150 to 250 l/ha. 
     Subsequent to the second and/or final applications the numbers and locations on the plant of the squares, flowers, and bolls were recorded, and when possible, either boll weights or seed cotton yields were obtained. 
     Greenhouse tests were conducted as follows: Cotton was sown in 2 to 5 liter pots in the greenhouse, approximately one plant per pot, either in field soil or soilless planting mix. Plants remained in the greenhouse, and at the matchhead square stage described in the field methods previously, treatments were applied to the foliage, squares, flowers, and/or bolls either by spraying in a laboratory chamber sprayer (e.g., Allen Machine Works, Midland, Mich.), or by placing the pots on the ground outside the greenhouse and spraying with a hand-held spray boom. Spray volumes were approximately equivalent to that described in the field methods. Plants were then returned to the greenhouse and boll counts, boll weights, or seed cotton yields were obtained from the plants. 
     2. Soybean trials. Soybean trials were conducted in a greenhouse. Soybean seeds were planted in 1000 ml pots in loamy sand soil, fertilized with a slow release fertilizer and allowed to germinate. Plants were thinned to two per pot. When the plants reached the third trifoliate stage, equivalent to 11 true leaves, the plants were treated with the appropriate spray solutions applied over the top of the plants to the foliage. 
     The plants were placed inside a laboratory spray chamber (Allen Machine Works, Midland Mich.). As noted above, the foliage was sprayed over the top in order to mimic a typical field application. The plants were returned to the greenhouse. Periodic height measurements, pod numbers, and general plant vigor assessments were conducted. At maturity (approximately six to eight weeks after spraying) the pods were harvested, counted, and the dry-weights recorded. 
     Control plants were either those completely untreated or those treated with mepiquat chloride (Pix® plant growth regulator&#34;) alone. Mepiquat chloride was applied either alone or in combination with the ethylene biosynthesis inhibitors at a rate of 12 to 200 g ai/ha. When applied in combination, the two compounds were applied using the same &#34;tank-mix&#34; spray solution. However, combinations of mepiquat chloride and ethylene biosynthesis inhibitors may also include separate applications made within 72 hours of each other on the same plants. 
     Other methods of applications for cotton, soybean and other crops are described below. 
     EXAMPLE 1 
     {(isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester unencapsulated (99% Technical Grade; BASF) was mixed either manually or with a magnetic stirrer in a volume of water equivalent to 150 to 250 l/ha for the area to be treated. The formulations were tested in cotton at 10 g ai/ha and 100 g ai/ha (single application; greenhouse). Ten untreated plants were used for the control. The weight of the bolls were obtained approximately 6 weeks after the first treatment. 
     The formulations were also tested in soybeans at 1, 10 and 20 g ai/ha (single application; greenhouse) and compared to an untreated control group and to a group treated with mepiquat chloride (PIX® plant growth regulator). 
     The results of the trials are displayed in Tables 1 and 2. 
     
                       TABLE 1                                                     
______________________________________                                    
(Cotton)                                                                  
Weight of Bolls                                                           
______________________________________                                    
rate kg ai/ha    0.010   0.10                                             
mc (0.200 kg     87      83                                               
ai/ha)                                                                    
tech.            99%     93                                               
______________________________________                                    
 mc = mepiquat chloride                                                   
 
    
     
                       TABLE 2                                                     
______________________________________                                    
(Soybean)                                                                 
Number of Pods                                                            
______________________________________                                    
rate kg ai/ha                                                             
             0.0010     0.010     0.02                                    
control      18.2       18.2      18.2                                    
mc (0.012 g ai/ha)                                                        
             19.2 (105%)                                                  
                        19.2 (105%)                                       
                                  19.2 (105%)                             
technical grade                                                           
             23.2 (127%)                                                  
                        18.4 (101%)                                       
                                  21.6 (119%)                             
______________________________________                                    
 mc = mepiquat chloride                                                   
 
    
     The results of the cotton trial show improvement when compared to those plants treated with mepiquat chloride alone at both the 1 and 20 g /ha rates, with the greatest improvement at the 1 g ai/ha rate. The data did not show an improvement from mepiquat chloride over the untreated check. 
     The experiment was also conducted with two applications at the same rates and comparable results were obtained. 
     The soybean data shows a substantial improvement of a plant growth factor at 20 and 1 g ai/ha rates (19% and 27%). Surprisingly, the low rate application at 1 g ai/ha showed a significant (27%) improvement over the untreated check 
     EXAMPLE 2 
     Formulations containing polyvinyl alcohol (PVA) encapsulated { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (99% Technical Grade; BASF Corporation) were prepared as described in U.S. patent application Ser. No. 08/771,319entitled &#34;Encapsulated Plant Growth Regulator Formulations&#34; filed on Dec. 20, 1996 . Briefly, a 10% solution of PVA in water was prepared and the pH was adjusted to about 4.1 using sodium phosphate dibasic as a buffer system. The oxime-ether was mixed into the PVA solution under high shear until a finely dispersed emulsion was obtained. A biocide (Proxel® GXI biocide) was added to the emulsion and mixed. The solution was passed once through a high shear Eiger Mini 50 (e.g., a bead mill with an 85% chamber loading of 1 mm glass beads) at 3000 RMP. A milky solution was obtained and passed through a 0.45 micron screen. A typical particle size obtained was 10 microns. The formulations prepared contained about 5% substituted oxime-ether, about 5% PVA, about 0.12% biocide, about 0.26% sodium phosphate dibasic and about 89.62% water. 
     Three encapsulated formulations were prepared using different PVA. The first formulation contained PVA having a molecular weight of 15-27K and partial hydrolysis of 87-89% (AIRVOL® 205 S, Air Products). The second formulation contained PVA having a molecular weight of 45-65K and a partial hydrolysis of 87-89% (AIRVOL® 523 S, Air Products). The third formulation contained PVA having a molecular weight of 70-90K and a partial hydrolysis of 87-89% (AIRVOL® 540 S, Air Products). 
     The formulations were tested in soybeans at rates of 1, 10 and 20 g ai/ha (greenhouse) and compared to a control and unencapsulated { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (99% Technical Grade; BASF Corporation). The results are displayed in Table 3. 
     
                       TABLE 3                                                     
______________________________________                                    
(Soybean)                                                                 
Number of Pods                                                            
______________________________________                                    
rate kg ai/ha  0.0010    0.010     0.020                                  
control        18.2      18.2      18.2                                   
tech. grade    23.2 (127%)                                                
                         18.4 (101%)                                      
                                   21.6 (119%)                            
encap. tech. grade (205S)                                                 
               23.2 (127%)                                                
                         21.8 (120%)                                      
                                   21.3 (118%)                            
encap. tech. grade (523S)                                                 
               20.4 (112%)                                                
                         22.6 (124%)                                      
                                   23.0 (126%)                            
encap. tech. grade (540S)                                                 
               25.8 (142%)                                                
                         19.2 (105%)                                      
                                   19.2 (105%)                            
______________________________________                                    
 
    
     The results establish that at low rates the encapsulated { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester significantly and consistently improves the number of pods in the soybean plant. 
     Yield studies in cotton were also performed using a PVA encapsulated compositions (540S as described above). Thirty-seven trials were carried out generally as described above for cotton field studies. The mean relative yields were calculated as compared to the values obtained for the untreated plants. The results are displayed in Table 4. 
     
                       TABLE 4                                                     
______________________________________                                    
(Cotton)                                                                  
Yield                                                                     
______________________________________                                    
Rate (g/ha)    0.5     1       10    20   50                              
Relative Yield 96%     100%    105%  97%  95%                             
Frequency of Positive Yield                                               
               18%      43%     59%  18%  25%                             
______________________________________                                    
 
    
     The best yield results (5%) were obtained at the 10 g/ha application rates. Also, the formulation applied at 10 g/ha had the highest frequency of positive results. The yields for the formulations applied at the 0.5, 20 and 50 g/ha rates were less than the untreated plants. The results for the plants treated with 1 g/ha application rates were the same as the results obtained for the untreated plants. 
     EXAMPLE 3 
     Formulations containing a mixture of { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (99% Technical Grade; BASF Corporation) and mepiquat chloride (PIX® plant growth regulator) were prepared by adding both active ingredients to an aqueous spray solution. Cotton plants were treated with 1 to 100 g /ha of the substituted oxime ether and 12, 100, or 200 g ai/ha mepiquat chloride (Pix® plant growth regulator) when used alone or in combination with the oxime ether. The formulations were applied with either two, three, or four applications during the course of the experiment at field test sites and in a greenhouse. Mepiquat chloride was used as a control. The number of squares, number of bolls, yield, plant height, and boll weight were calculated. Yield data was measured as either kg/plot or lb/a. The results are listed in Tables 5-8. The results are displayed as percent of the plants treated with mepiquat chloride (&#34;mc&#34;) alone. 
     
                                           TABLE 5                                 
__________________________________________________________________________
Number of Squares.sup.1                                                   
__________________________________________________________________________
Rate (kg ai/ha)                                                           
         0.001 0.010 0.020 0.050 0.10                                     
mc       8.3   8.3   8.3   8.3   8.3                                      
mc + tech.                                                                
         10.3 (124%)                                                      
               8.2 (99%)                                                  
                     8.11 (98%)                                           
                           9.0 (108%)                                     
                                 8.2 (99%)                                
__________________________________________________________________________
 .sup.1 data from mapping done after 2nd of 4 applications (Field Data);  
 mc = mepiquat chloride                                                   
 
    
     
                                           TABLE 6                                 
__________________________________________________________________________
Number of Bolls                                                           
__________________________________________________________________________
Rate (kg ai/ha)                                                           
         0.001 0.010 0.020 0.050 0.10                                     
mc.sup.1 7.8   7.8   7.8   7.8   7.8                                      
mc + tech.sup.1                                                           
         10.7 (137%)                                                      
               9.5 (122%)                                                 
                     8.3 (106%)                                           
                           8.5 (109%)                                     
                                 9.3 (119%)                               
mc.sup.2 4.1   4.1   4.1   4.1   4.1                                      
mc + tech..sup.2                                                          
          4.9 (122%)                                                      
               4.4 (107%)                                                 
                     5.3 (129%)                                           
                           5.5 (134%)                                     
                                 5.3 (129%)                               
mc.sup.3 7.2   7.2   7.2   7.2   7.2                                      
mc + tech..sup.3                                                          
          5.5  (77%)                                                      
               6.5  (90%)                                                 
                     5.5  (77%)                                           
                           5.8  (80%)                                     
                                 5.8  (80%)                               
mc + tech..sup.4                                                          
               86%               82%                                      
__________________________________________________________________________
 .sup.1 Four applications (field test)                                    
 .sup.2 Three applications (field test)                                   
 .sup.3 Four applications (greenhouse)                                    
 .sup.4 Two applications (greenhouse)                                     
 mc = mepiquat chloride                                                   
 
    
     
                                           TABLE 7                                 
__________________________________________________________________________
Yield                                                                     
__________________________________________________________________________
Rate (kg ai/ha)                                                           
         0.0010                                                           
               0.010 0.020 0.050 0.1                                      
mc.sup.1 3.6   3.6   3.6   3.6   3.6                                      
mc + tech..sup.1                                                          
         4.0 (111%)                                                       
               4.1 (114%)                                                 
                     4.3 (119%)                                           
                           3.7 (103%)                                     
                                 3.4 (94%)                                
mc.sup.2 2.18  2.18  2.18  2.18  2.18                                     
mc + tech..sup.2                                                          
         2.66  2.33  2.67  2.88  2.39                                     
         (123%)                                                           
               (107%)                                                     
                     (122%)                                               
                           (132%)                                         
                                 (109%)                                   
__________________________________________________________________________
 .sup.1 Four applications (field test)                                    
 .sup.2 Three applications (field test)                                   
 mc = mepiquat chloride                                                   
 
    
     
                       TABLE 8                                                     
______________________________________                                    
Weight of Bolls.sup.1                                                     
______________________________________                                    
rate (kg ai/ha)  0.010   0.10                                             
mc (0.200 kg      87%    83%                                              
ai/ha)                                                                    
mc + tech.       116%    97%                                              
tech.             99%    93%                                              
______________________________________                                    
 .sup.1 Two applications (greenhouse)                                     
 mc = mepiquat chloride                                                   
 
    
     The data demonstrates that applications rates of less than 50 g ai/ha provided the most consistent and maximum response. Two-thirds of the cases for the number of bolls showed an improvement at application rates less than 50 g ai/ha. Similarly, two-thirds of the cases for the yield data showed a substantial improvement. An improvement was shown in over one-half of the tests for the substituted oxime ether applied at rates less than 50 g ai/ha. 
     Eleven additional field trials were conducted in cotton. Plants were treated with mepiquat chloride alone and in combination with { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (99% Technical Grade, BASF). The mepiquat chloride was applied at 12 g/ha in all applications. The { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (99% Technical Grade, BASF (&#34;technical grade&#34;)) was applied at rates of 1 g/ha, 10 g/ha, 20 g/ha and 50 g/ha. The mean values (yield) for the treated plants were calculated and compared to the mean values obtained for the untreated plants. The results are displayed in Table 9. 
     
                       TABLE 9                                                     
______________________________________                                    
(Cotton)                                                                  
Yield                                                                     
______________________________________                                    
rate (g/ha)     1       10      20    mc alone                            
mc (12 g/ha)                          101%                                
Relative Yield of mc +                                                    
                106%    104%     85%  101%                                
technical grade                                                           
Frequency of Positive Yield                                               
                 73%     54%     0    36%                                 
______________________________________                                    
 mc = mepiquat chloride                                                   
 
    
     The data in Table 9 indicates that the best results are obtained at the lowest rates, i.e., less than or equal to 10 g/ha. The highest frequency of positive yield was obtained at 1 g/ha. 
     The same formulations were used to treat soybean plants and compared to untreated plants, plants treated with mepiquat chloride and plants treated with { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester. The results are listed in Table 10. 
     
                       TABLE 10                                                    
______________________________________                                    
(Soybeans)                                                                
Number of Pods.sup.1                                                      
______________________________________                                    
rate (kg ai/ha)                                                           
               0.001     0.010     0.020                                  
control        18.2      18.2      18.2                                   
mc (0.012 kg ai/ha)                                                       
               19.2 (105%)                                                
                         19.2 (105%)                                      
                                   19.2 (105%)                            
tech. grade    23.2 (127%)                                                
                         18.4 (101%)                                      
                                   21.6 (119%)                            
tech. + mc     22.6 (124%)                                                
                         16.8  (92%)                                      
                                   19.6 (108%)                            
______________________________________                                    
 .sup.1 One application (greenhouse)                                      
 mc = mepiquat chloride                                                   
 
    
     In this experiment, the low rate treatment (1 g ai/ha) using the oxime-ether and mepiquat chloride combination provided a significant improvement (27%) in the number of pods when compared to the untreated control and compared to application rates higher than 1 g ai/ha. 
     EXAMPLE 4 
     Encapsulated { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester formulations were prepared as in Example 2 and combined with mepiquat chloride and mixed in one liter of water. Three formulations were prepared. The first formulation contained PVA with a molecular weight of 44-66K and partial degree of hydrolysis (87-89%) (AIRVOL® 523 S polyvinyl alcohol). The second formulation contained PVA with a molecular of 70-90k and was partially hydrolyzed (87-89%) (Airvol 540® polyvinyl alcohol). The third contained PVA with molecular weight 15-27K, and was also partially hydrolyzed (87-89%) (Airvol ® 205S polyvinyl alcohol). Cotton plants were treated as described above. The plants were treated and mepiquat chloride treated plants were used as a comparison (Application rate at about 0.012 kg ai/ha in all studies). The number of squares and bolls were measured and the results as a percent of the plants treated with mepiquat chloride alone are displayed in Tables 11-13. 
     
                                           TABLE 11                                
__________________________________________________________________________
(Cotton)                                                                  
Number of Squares.sup.1                                                   
__________________________________________________________________________
rate (kg ai/ha)                                                           
         0.001 0.010 0.020 0.050 0.10                                     
mc       8.3   8.3   8.3   8.3   8.3                                      
mc + encap. w/523S                                                        
         11.3 (136%)                                                      
               10.7 (129%)                                                
                     8.7 (105%)                                           
                            9.8 (118%)                                    
                                 8.9 (107%)                               
mc + encap. w/540S                                                        
          9.8 (118%)                                                      
               10.5 (126%)                                                
                     8.2  (99%)                                           
                           10.1 (122%)                                    
                                 7.0  (84%)                               
__________________________________________________________________________
 .sup.1 Measured after two of four sequential applications (field test)   
 mc = mepiquat chloride                                                   
 
    
     
                                           TABLE 12                                
__________________________________________________________________________
(Cotton)                                                                  
Number of Bolls                                                           
__________________________________________________________________________
rate (kg ai/ha) 0.001 0.010 0.020 0.050 0.10                              
mc.sup.1        7.8   7.8   7.8   7.8   7.8                               
mc + encap. w/523S.sup.1                                                  
                10.0 (128%)                                               
                      8.1 (104%)                                          
                            7.3   7.6   9.2                               
mc + 3encap. w/540S.sup.1                                                 
                 9.9 (127%)                                               
                      7.6  (97%)                                          
                            9.0 (115%)                                    
                                  7.3  (94%)                              
                                        6.9  (88%)                        
mc.sup.2        4.1   4.1   4.1   4.1   4.1                               
mc + encap. w/523S.sup.2                                                  
                5.7 (139%)                                                
                      5.3 (129%)                                          
                            5.8 (142%)                                    
                                  6.2 (151%)                              
                                        6.4 (156%)                        
mc + encap. w/540S.sup.2                                                  
                6.2 (151%)                                                
                      8.3 (202%)                                          
                            6.1 (149%)                                    
                                  6.2 (151%)                              
                                        5.9 (144%)                        
mc.sup.3        7.2   7.2   7.2   7.2   7.2                               
mc + encap. w/523S.sup.3                                                  
                6.2  (86%)                                                
                      7.2 (100%)                                          
                            6.5  (90%)                                    
                                  6.5  (80%)                              
                                        6.2  (86%)                        
mc + encap. w/540S.sup.3                                                  
                9.0 (125%)                                                
                      7.0  (97%)                                          
                            7.8  (94%)                                    
                                  6.8  (94%)                              
                                        7.3 (101%)                        
mc.sup.4        3.35  3.35        3.35                                    
mc + encap. w/523S.sup.4                                                  
                3.65 (109%)                                               
                      3.90 (116%) 3.95 (118%)                             
mc + encap. w/540S.sup.4                                                  
                4.22 (126%)                                               
                      3.60 (108%) 3.30  (99%)                             
__________________________________________________________________________
 .sup.1 Four applications (field data)                                    
 .sup.2 Three applications (field data)                                   
 .sup.3 Four applications (field data)                                    
 .sup.4 Collected after the second of two sequential applications         
 mc = mepiquat chloride                                                   
 
    
     
                                           TABLE 13                                
__________________________________________________________________________
(Cotton)                                                                  
Yield                                                                     
__________________________________________________________________________
rate (kg ai/ha)                                                           
       0.001  0.010  0.020  0.050  0.10                                   
mc.sup.1                                                                  
       1365   1365   1365   1365   1365                                   
mc + 523S.sup.1                                                           
       1669 (122%)                                                        
              1252  (92%)                                                 
                     1290  (94%)                                          
                            1138  (83%)                                   
                                   1252  (92%)                            
mc + 540S.sup.1                                                           
       1024  (75%)                                                        
              1290  (94%)                                                 
                     1328  (97%)                                          
                            1138  (83%)                                   
                                   1100  (81%)                            
mc.sup.2                                                                  
       2.18   2.18   2.18   2.18   2.18                                   
mc + 523S.sup.2                                                           
       2.87 (131%)                                                        
              3.25 (149%)                                                 
                      2.8 (128%)                                          
                            2.76 (127%)                                   
                                   2.82 (129%)                            
mc + 540S.sup.2                                                           
       3.43 (157%)                                                        
              3.44 (158%)                                                 
                     3.57 (164%)                                          
                             3.4 (156%)                                   
                                   3.27 (150%)                            
__________________________________________________________________________
 .sup.1 Four applications (field test)                                    
 .sup.2 Three applications (field test)                                   
 mc = mepiquat chloride                                                   
 
    
     Examination of the data in Tables 10-14 confirms that the present invention provides consistent improvement in plant growth factor at low rates. For example, at the low rate application of 1 g ai/ha, the formulation provides significant improvement (about 5% to about 60%) over the mepiquat chloride treated plants. 
     Thirty-four additional field trials were conducted using the PVA encapsulated formulations (540S) in combination with mepiquat chloride. The mepiquat chloride was applied, for all trials, at a rate of 12 g/ha. The { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester was applied at 0.5 g/ha, 1 g/ha, 10 g/ha, 20 g/ha and 50 g/ha. The results are displayed as a percent in Table 14. 
     
                       TABLE 14                                                    
______________________________________                                    
Relative % Yield                                                          
______________________________________                                    
rate (g/ha)  0.5 g   1 g     10 g  20 g  50 g                             
mc (12 g/ha) 103%    103%    103%  104%  103%                             
mc + PVA Encap.                                                           
             110%    105%    106%  99%   90%                              
Forms.                                                                    
Frequency of 64%     72%     77%   56%   25%                              
Positive Yields                                                           
______________________________________                                    
 mc = mepiquat chloride                                                   
 
    
     The results for the plants treated with mepiquat chloride alone had a mean value of 103% when compared to the untreated plants with a frequency of positives of 60% of the untreated. Maximum yield for the combination was at 0.5 g/ha rate. Significant increase was seen with the combination below 20 g/ha. 
     The formulations were also tested in soybeans at rates of 1, 10 and 20 g/ha (greenhouse) and compared to an untreated control. The formulations showed an improvement over the untreated control and were comparable to the plants treated with mepiquat chloride. 
     Another soybean greenhouse study was repeated with the 540S formulations. Mean yield data was obtained (seed weight) at 1, 10 and 50 g/ha. The data obtained showed a decrease in yield when measured as percent of the untreated plants (26%, 30% and 24% at the 1, 10 and 50 g/ha rates respectively). 
     EXAMPLE 5 
     A greenhouse trial was conducted in cotton plants (cv. Delta Pine 50). Single plants were raised on a peat-based substrate in 5 liter containers. Water and nutrients were applied uniformly as needed. The plants were leaf-treated with aqueous sprays of PVA encapsulated { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (540S) in combination with mepiquat chloride the plants were treated at growth stage 61 (beginning of flowering) using approximately 500 l/ha of liquid. The plants were also treated with mepiquat chloride alone. For all studies, mepiquat chloride was applied at rates of 10 and 100 g/ha. The { (isopropylidene)-amino!oxy}-acetic acid-2-(METHOXY)-2-oxoethyl ester was applied at rates of 10 and 100 g/ha. Two days after treatment a one week drought stress was imposed onto part of the plants by reducing water supply to approximately 30% of the regular dosage. The leaves of the plants were thus permanently wilted but not killed. Bolls were harvested fresh when the old ones of the control plants had reached their final size. The shoot length, the number of bolls per plant and the fresh weight of bolls per plant were assessed and calculated. The results did not show consistent improvement over the untreated. Although some improvement was observed over untreated and mepiquat treated plants, there was also observed decreases in the shoot length and the number of bolls at both rates. 
     For the shoot length measurements, the results of the combination were from 84% to 93% (measured as a % of the untreated). In the drought stressed treated plants the results for the combination ranged from 93% to 99% of the untreated. The results for the 540S formulations was 100% of the untreated at 10 g/ha and 103% of the untreated at 100 g/ha (108% and 97% at the 10 g/ha and 100 g/ha, respectively, for the drought stressed plants). The plants treated with mepiquat chloride alone showed a decrease in shoot length, 95% of the untreated at 10 g/ha and 85% of the untreated at 100 g/ha (97% and 96% for the water stressed plants. 
     The number of bolls ranged from 84% to 102% of the untreated, for the plants treated with the combination (94% to 100% for the drought stressed plants, respectively). The number of bolls for the 540S treated plants was 100% of the untreated at the 10 g/ha and 97% of the untreated at 100 g/ha (106% and 103% for the drought stressed plants). The results for the plants treated with mepiquat chloride alone was 92% of the untreated for the plants treated at 10 g/ha and 87% of the untreated at 100 g/ha (102% and 95% for the drought stressed plants respectively). 
     The fresh weight bolls per plant was measured and ranged from 89% to 95% of the untreated for the plants treated with the combination (87% to 101% for the drought stressed plants respectively). The results for the 540S treated plants were 97% of the untreated at the 10 g/ha rate and 91% of the untreated at the 100 g/ha (96% and 103% for the drought stressed plants). The results for the plants treated with mepiquat chloride alone were 95% for the untreated at 10 g/ha and 87% of the untreated at 100 g/ha (96% and 113% for the drought stressed plants respectively). 
     EXAMPLE 6 
     Dryland (non-irrigated) winter wheat was grown in the field. PVA encapsulated { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester, prepared as described in Example 2 (540S), was applied as a foliar treatments in wheat at 1, 10, 20, and 50 g ai/ha rates, beginning at elongation and continuing every 14 days thereafter for four sequential applications. The trials were conducted in a randomized complete block design, plots 10&#39;×40&#39;, replicated 4 times. The compositions were applied with a flat boom backpack CO 2  sprayer, 20 GPA, in an aqueous carrier. Upon maturity, the wheat grain was harvested with a plot combine and the grain yield was recorded. The mean values of yield of the treated plants as compared to the values obtained for the untreated plants was recorded and the data is displayed in Table 15. 
     
                       TABLE 15                                                    
______________________________________                                    
(Wheat)                                                                   
Rate     1 g ai/ha 10 g ai/ha                                             
                             20 g ai/ha                                   
                                     50 g ai/ha                           
______________________________________                                    
Yield    110%      107%      113%    111%                                 
______________________________________                                    
 (Rates expressed as per application, each application a total of 4 times)
 
    
     The results show an improvements in yield up to 13% of the untreated control. However, the results were non-significant at p=0.05. 
     EXAMPLE 7 
     Cherry tomatoes were grown in a greenhouse in large pots and treated with foliar spray applications (20 GPA) of PVA encapsulated  (isopropylidene)-amino!oxy}-ACETIC acid-2-(methoxy)-2-oxoethyl ester, prepared as described in Example 2 (540S). The plants were treated when the 3rd cluster of fruit (youngest at the time of application) was in the small bud stage. First and second clusters were blooming. Foliar applications were of 1, 3, 10, 30, and 100 g/ha rates in aqueous solutions. The fruits were harvested at maturity, counted, and the fresh weights were recorded and compared to the untreated plants. The results, relative to the untreated plants, are displayed in Table 16. 
     
                       TABLE 16                                                    
______________________________________                                    
(Tomatoes)                                                                
Rate        1 g     3 g     10 g   30 g  100 g                            
______________________________________                                    
3rd Cluster Yield                                                         
            97%     121%    105%   85%   85%                              
# of Fruit  127%    110%    103%   111%  79%                              
2nd Cluster Yield                                                         
            89%     109%    109%   93%   90%                              
# of Fruit  92%     96%     98%    91%   95%                              
1st Cluster Yield                                                         
            101%    86%     90%    94%   98%                              
# of Fruit  97%     82%     100%   100%  105%                             
______________________________________                                    
 
    
     Improvement of fresh weight was obtained at 3 and 10 g ai/ha in the 2nd and 3rd clusters, and the number of fruits improved in the 1 st cluster (30-100 g/ha) and the 3rd cluster (1 g/ha). Best results were achieved with foliar application to the young bud stage at rates of equal to or less than 10 g ai/ha. A similar trial conducted in the greenhouse on beefsteak tomatoes resulted in no improvement in fruit yields or fruit numbers. 
     EXAMPLE 8 
      (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (Technical grade BASF Corporation) was applied as a foliar spray application to pepper plants (bud stage) grown in the greenhouse. Aqueous solutions of { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester was applied at rates of 1, 3, 10, 30 and 100 g ai/ha rates. The fruit was harvested upon maturity, counted, and fresh weights recorded. The results were calculated as percent of the untreated plants and they are displayed in Table 17. 
     
                       TABLE 17                                                    
______________________________________                                    
Rate (g/ha)                                                               
        1        3        10     30     100                               
______________________________________                                    
# Fruit 121%     115%     124%   112%   117%                              
Yield   118%     110%     123%   107%    95%                              
______________________________________                                    
 
    
     Improvements of both fruit numbers and fresh weight yields were obtained, particularly at rates of 10 g ai/ha and below (not significant at p=0.05). 
     EXAMPLE 9 
      (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (99% Technical Grade, BASF) and encapsulated formulations (205S, 523S, and 540S formulations), prepared as described under Example 2, were applied in 4-6 sequential foliar applications in three small-plot field trials on established turf grass (fescue, bluegrass, and zoysia turfs). Experiments were conducted in a randomized complete block with 4 replications. The treatments were applied as a foliar spray application with a spray volume of approximately 40 gallons per acre in an aqueous dilution at rates of 1, 5, 10, and 20 g ai/ha per application. After the final application, two 2-inch soil cores were taken from the first replication of each trial. The cores were washed and visually evaluated for increases in root mass. Visually obvious increases in root mass were noted in fescue in the 523S and 540S formulation treatments, in bluegrass with the technical grade (10 g and lower), and in zoysia (technical grade below 10 g/ha and the 523S formulations at all rates). 
     Further controlled studies were conducted in greenhouse on bentgrass and bermudagrass that had been established and mowed several times in 4 inch pots. The study was replicated 7 times. The 523S PVA formulation was applied at 1, 5, 10 and 20 g ai/ha. In one treatment method, the compound was applied in an aqueous foliar spray 24 hours prior to cutting and transplanting from the original container. In the second treatment method, the turf was cut and transplanted and then sprayed with an aqueous foliar application. In a third treatment method, the turf was cut and transplanted and treated with a 50 ml volume of aqueous solution with equivalent active ingredient as that applied in the spray applications. The transplanted turf was removed from the pots, washed, and visual observations were made. Root and shoot dry weights and root lengths measured were measured. The results for bentgrass are displayed in Table 18. 
     
                       TABLE 18                                                    
______________________________________                                    
Rate (g/ha)                                                               
           1 g       5        10      20                                  
______________________________________                                    
Root Dry Wt.                                                              
           205%      331%*    131%    280%*                               
Root Length                                                               
           134%      153%*    144%*   123%                                
Shoot Dry Wt.                                                             
           149%*     129%*    115%    145%*                               
______________________________________                                    
 All values relative to control treated with equivalent amount of water.  
 *denotes significance at p = 0.05.                                       
 
    
     The data show a significant increase (p=0.05) in root dry weight and length and shoot dry weight in bentgrass when the drench method is used. The data also show a significant increase in root dry weight and length in bermudagrass with the drench application (20 g a/ha), and increase in root dry weight with application prior to cutting (1 g ai/ha). For example, the shoot dry weight of the treated turf showed an increase over the untreated of 49%, 29%, 15% and 45% at the 1, 5, 10 and 20 g/ha rates of applications. 
     EXAMPLE 10 
     A composition containing { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy) -2-oxoethyl ester (99% Technical Grade, BASF) in a solvent having an emulsifier system was prepared. A C8 pyrrolidone solvent (AGSOLEX® 8, 1-Octylpyrrolidone, ISP) was mixed with an emulsifier System containing a block copolymer (PLURAFAC® LF-700, BASF) and an emulsifier comprising a blend of 80% nonyl phenol ethoxylate (MAKON®, Stepan Chemical) and 20% dioctyl sulfosuccinate (AERSOL® OT 100). The resulting solution was mixed until a clear homogenous solution was formed. { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester (99% Technical Grade, BASF) was added to the clear solution and mixed until a clear homogenous solution was formed. The resulting composition contained about 82.6% C8 pyrrolidone, about 8.3% block copolymer emulsifier, about 4.1% of the emulsifier and about 5.0% of the { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester. This resulting composition was mixed with PIX® mepiquat chloride plant growth regulator (BASF Corporation) such that the mepiquat chloride was applied to cotton in field studies at a rate of 12 g/ha and the { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester contained in the solvent with an emulsifier system was applied at 1 and 10 g/ha. The results are displayed in Table 19. 
     
                       TABLE 19                                                    
______________________________________                                    
(Cotton)                                                                  
Yield                                                                     
______________________________________                                    
Rate (g/ha)       1        10       mc                                    
Relative Yield    103%     106%     102%                                  
(% compared to untreated))                                                
Frequency of Positive Yield                                               
                   62%      62%      38%                                  
______________________________________                                    
 mc = mepiquat chloride                                                   
 
    
     The results show that the treated plants had a 3% and 6% increase over the untreated plants at 1 and 10 g/h rates respectively--with a frequency of positive yield of 62%. 
     EXAMPLE 11 
     Field studies were performed with mepiquat chloride (PIX® plant growth regulator) in combination with { (isopropylidene)-amino!oxy}-acetic acid-2-(methoxy)-2-oxoethyl ester--in three formulations: 1) 99% Technical Grade, BASF Corporation; 2) PVA encapsulated (540S); and 3) solvent containing an emulsifier system (as described in Example 10). The mepiquat chloride was applied at 12 g/ha for all applications. Plants treated with mepiquat chloride alone were also evaluated for yield. The mean value for the mepiquat chloride samples was 103% over the untreated. The mean values for all combinations (as percent of yield for the mepiquat chloride treated plants) was obtained for all trials and are summarized below in Table 20. 
     
                       TABLE 20                                                    
______________________________________                                    
                   Number of                                              
Rate (g/ha)                                                               
         Yield (%) comparisons                                            
                              Frequency of positives                      
______________________________________                                    
0.5      108       11         64%                                         
1.0      104       75         63%                                         
10       104       83         55%                                         
______________________________________                                    
 
    
     The results show that the mean value of the plants treated with the combination had improvements of 8%, 4% and 4% at the 0.5, 1, and 10 g/ha rates, respectively, when compared to the mepiquat chloride treated plants. Where trials included an untreated control, combinations had improvements of 10%, 5%, and 6% when compared to the untreated controls. Mepiquat chloride applied alone resulted in an mean yield increase of 3% over the untreated control when all field trials conducted are summarized. 
     Experiments were also performed in drought stressed cotton. The mean values for all combinations (as percent of the plants treated with mepiquat chloride) was obtained for all trials and are summarized below in Table 21. 
     
                       TABLE 21                                                    
______________________________________                                    
                   Number of                                              
Rate (g/ha)                                                               
         Yield (%) comparisons                                            
                              Frequency of positives                      
______________________________________                                    
0.5      115       3          67%                                         
1.0      113       14         86%                                         
10       114       14         64%                                         
______________________________________                                    
 
    
     The results show that the mean value of the plants treated with the combination had improvements of 15%, 13% and 14% at the 0.5, 1, and 10 g/ha rates, respectively, when compared to the mepiquat chloride treated plants. Because the plants treated with mepiquat chloride alone showed an average (mean) increase of 9% (80% positive response; average of seven trials) over the untreated, these results indicated a 6%, 4%, and 5% improvement over the untreated plants at the 0.5, 1 and 10 g/ha rates, respectively. 
     The invention has been described with reference to various specific embodiments. However, many variations and modifications may be made while remaining within the scope and spirit of the invention.