Plant growth regulation compositions and methods using gibberellin biosynthesis inhibitor combinations

Abstract

Described are plant growth regulation compositions and methods utilizing combinations of Class A and Class B gibberellin biosynthesis inhibitors. Preferred methods and compositions involve the combination of trinexapac-ethyl with either or both of flurprimidol and paclobutrazol, in particular to provide a synergistic effect in the regulation of the growth of turfgrass.

1 . A method for regulating plant growth, comprising: 
 applying to a plant a Class A gibberellin biosynthesis inhibitor; and    applying to the plant a Class B gibberellin biosynthesis inhibitor;    wherein said Class A and Class. B gibberellin synthesis inhibitors exhibit synergism in regulating growth of the plant.    
   
   
       2 . A method according to  claim 1 , wherein: 
 said Class A gibberellin synthesis inhibitor-is encompassed by the formula:                          wherein    A is an —OR 2  or —NR 3  R 4  radical,    R is C 3 -C 6  cycloalkyl,    R 2  R 3  and R 4  are each independently hydrogen, C 1 -C 6  alkyl, C 1 -C 6  haloalkyl, C 2 -C 10  alkoxyalkyl, C 2 -C 10  alkylthioalkyl, C 3 -C 6  alkenyl, which is unsubstituted or substituted by halogen, C 1 -C 4  alkoxy or C 1 -C 4  alkylthio; C 3 -C 6  alkynyl; phenyl or C 1 -C 6  aralkyl, wherein the phenyl nucleus is unsubstituted or substituted by halogen, C 1 -C 4  alkyl, C 1 -C 4  alkoxy,    C 1 -C 4  haloalkyl, nitro or cyano; one of R 3  and R 4  is methoxy; or    R 3  and R 4 , together with the nitrogen atom to which they are attached, form a 5- or 6- membered heterocyclic ring system which may contain an additional oxygen or sulfur atom in the ring; and the metal or ammonium salts thereof.    
   
   
       3 . A method according to  claim 2 , wherein the Class A gibberellin synthesis inhibitor is trinexapac-ethyl.  
   
   
       4 . A method according to  claim 1 , wherein the Class B gibberellin synthesis inhibitor is encompassed by the formula:  
     
       
         
         
             
             
         
       
       wherein  
       R 5  is alkenyl, alkynyl or optionally substituted aralkyl;  
       Y is ═N— or ═CH—;  
       R 6  is cycloalkyl, alkyl or haloalkyl; and  
       R 7  is hydrogen, methyl or alkenyl, or an ester, an ether, an acid addition salt or a metal complex thereof.  
     
   
   
       5 . A method according to  claim 4 , wherein the Class B gibberellin synthesis inhibitor is paclobutrazol.  
   
   
       6 . A method according to  claim 1 , wherein: 
 the Class B gibberellin synthesis inhibitor is encompassed by the formula:                          wherein    R 8  is 2-pyrazinyl, 3-pyridyl, or 5-pyrimidinyl;    R 9  is phenyl, pyridyl, C 1 -C 12  alkyl, or C 3 -C 8  cycloalkyl;    R 10  is trifluoromethoxy phenyl, tetrafluoroethoxyphenyl, pentafluoroethoxyphenyl, 3,4-(difluoromethylenedioxy)phenyl, or 2,2,4,4-tetrafluoro-1,3-benzodioxanyl;    X is hydrogen, hydroxy, lower alkoxy, lower alkylthio, or lower alkanoyloxy;    or an acid addition salt thereof.    
   
   
       7 . A method according to  claim 6 , wherein the Class B gibberellin synthesis inhibitor is flurprimidol.  
   
   
       8 . A method according to  claim 1 , wherein the Class A and Class B gibberellin biosynthesis inhibitors are applied together.  
   
   
       9 . A method according to  claim 1 , wherein the Class A and Class B gibberellin biosynthesis inhibitors are applied separately.  
   
   
       10 . A method according to  claim 1 , wherein the plant is turfgrass.  
   
   
       11 . A method according to  claim 10 , wherein the Class A gibberellin biosynthesis inhibitor is trinexepac-ethyl, and wherein the trinexepac-ethyl is applied at a level of about 0.02 to about 0.7 pounds of active ingredient per acre.  
   
   
       12 . A method according to  claim 11 , wherein the Class B gibberellin biosynthesis inhibitor is flurprimidol, and wherein the flurprimidol is applied at a level of about 0.05 to about 1.5 pounds of active ingredient per acre.  
   
   
       13 . A method according to  claim 11 , wherein the Class B gibberellin biosynthesis inhibitor is paclobutrazol, and wherein the paclobutrazol is applied at a level of about 0.05 to 1.0 pounds of active ingredient per acre.  
   
   
       14 . A method according to  claim 10 , wherein the Class A and Class B gibberellin biosynthesis inhibitors are applied together.  
   
   
       15 . A method according to  claim 10 , wherein the Class A and Class B gibberellin biosynthesis inhibitors are applied separately.  
   
   
       16 . A method according to  claim 14 , wherein the turfgrass comprises one or more grasses selected from as Bahiagrass ( Paspalum notatum ); Bermudagrass ( Cynodon dactylon ); Buffalograss ( Buchloe dactyloides ); Carpetgrass ( Axonopus affinis ); Centipedegrass ( Eremochloa ophiuroides ); Kikuyugrass ( Pennisetum cladestinum ); Seashore paspalum ( Paspalum vaginatum ); St. Augustinegrass ( Stenotaphrum secundatum ); Zoysiagrass ( Zoysia matrella  ( japonica )); Annual ryegrass ( Lolium multiflorum ); Bentgrass ( Agrostis  spp.); Fescue ( Festuca  spp.); Kentucky bluegrass ( Poa pratensis ); Perennial ryegrass ( Lolium perenne ); and  Poa annua.    
   
   
       17 . A method according to  claim 14 , wherein the turfgrass comprises one or more grasses selected from Bermudagrass ( Cynodon dactylon ); Annual ryegrass ( Lolium multiflorum ); Bentgrass ( Agrostis  spp.); Kentucky bluegrass ( Poa pratensis ); and Perennial ryegrass ( Lolium perenne ).  
   
   
       18 . A composition for regulating plant growth, comprising: 
 a Class A gibberellin biosynthesis inhibitor; and    a Class B gibberellin biosynthesis inhibitor;    wherein said biosynthesis inhibitors exhibit synergism in the regulation of plant growth.    
   
   
       19 . A composition according to  claim 18 , wherein: 
 said Class A gibberellin synthesis inhibitor is encompassed by the formula:                          wherein    A is an —OR 2  or —NR 3  R 4  radical,    R is C 3 -C 6  cycloalkyl,    R 2  R 3  and R 4  are each independently hydrogen, C 1 -C 6  alkyl, C 1 -C 6  haloalkyl, C 2 -C 10  alkoxyalkyl, C 2 -C 1 o alkylthioalkyl, C 3 -C 6  alkenyl, which is unsubstituted or substituted by halogen, C 1 -C 4  alkoxy or C 1 -C 4  alkylthio; C 3 -C 6  alkynyl; phenyl or C 1 -C 6  aralkyl, wherein the phenyl nucleus is unsubstituted or substituted by halogen, C 1 -C 4  alkyl, C 1 -C 4  alkoxy,    C 1 -C 4  haloalkyl, nitro or cyano; one of R 3  and R 4  is methoxy; or    R 3  and R 4 , together with the nitrogen atom to which they are attached, form a 5- or 6-membered heterocyclic ring system which may contain an additional oxygen or sulfur atom in the ring; and the metal or ammonium salts thereof.    
   
   
       20 . A composition according to  claim 18 , wherein the Class A gibberellin synthesis inhibitor is trinexapac-ethyl.  
   
   
       21 . A composition according to  claim 18 , wherein the Class B gibberellin synthesis inhibitor is encompassed by the formula:  
     
       
         
         
             
             
         
       
       wherein  
       R 5  is alkenyl, alkynyl or optionally substituted aralkyl;  
       Y is ═N— or ═CH—;  
       R 6  is cycloalkyl, alkyl or haloalkyl; and  
       R 7  is hydrogen, methyl or alkenyl, or an ester, an ether, an acid addition salt or a metal complex thereof.  
     
   
   
       22 . A composition according to  claim 21 , wherein the Class B gibberellin synthesis inhibitor is paclobutrazol.  
   
   
       23 . A composition according to  claim 18 , wherein: 
 the Class B gibberellin synthesis inhibitor is encompassed by the formula:                          wherein    R 8  is 2-pyrazinyl, 3-pyridyl, or 5-pyrimidinyl;    R 9  is phenyl, pyridyl, C 1 -C 12  alkyl, or C 3 -C 8  cycloalkyl;    R 10  is trifluoromethoxyphenyl, tetrafluoroethoxyphenyl, pentafluoroethoxyphenyl, 3,4-(difluoromethylenedioxy)phenyl, or 2,2,4,4-tetrafluoro-1,3-benzodioxanyl;    X is hydrogen, hydroxy, lower alkoxy, lower alkylthio, or lower alkanoyloxy;    or an acid addition salt thereof.    
   
   
       24 . A composition according to  claim 23 , wherein the Class B gibberellin synthesis inhibitor is flurprimidol.  
   
   
       25 . A composition according to  claim 18 , wherein: 
 the Class A gibberellin biosynthesis inhibitor is trinexepac-ethyl, and wherein the trinexepac-ethyl is present in the composition at a concentration of about 0.5 to about 3 pounds per gallon.    
   
   
       26 . A composition according to  claim 18 , wherein: 
 the Class B gibberellin biosynthesis inhibitor is flurprimidol, and wherein the flurprimidol is present in the composition at a concentration of about 0.5 to about 3 pounds per gallon.    
   
   
       27 . A composition according to  claim 18 , wherein: 
 the Class B gibberellin biosynthesis inhibitor is. paclobutrazol, and wherein the paclobutrazol is present in the composition at a level of about 0.5 to about 3 pounds per gallon.    
   
   
       28 . A composition according to  claim 26 , adapted for application to turfgrass.  
   
   
       29 . A composition according to  claim 27 , adapted for application to turfgrass.  
   
   
       30 . A method according to  claim 28 , wherein the turfgrass comprises one or more grasses selected from Bermudagrass ( Cynodon dactylon ); Annual ryegrass ( Lolium multiflorum ); Bentgrass ( Agrostis  spp.); Kentucky bluegrass ( Poa pratensis ); and Perennial ryegrass ( Lolium perenne ).  
   
   
       31 . A composition according to  claim 18 , which comprises an aqueous carrier.  
   
   
       32 . A composition according to  claim 18 , wherein the Class A and Class B gibberellin biosynthesis inhibitors are present in a molar ratio of about 1:0.625 to about 1:5.