Peroxy acid treatment to control pathogenic organisms on growing plants

Abstract

A method of using peracid/acid compositions, where the mole ratio of acid to peracid is less than about 3:1, to treat field or greenhouse grown plant tissue, seeds, fruits, and growing media and containers is described. The peracid/acid system can lower the natural, plant pathogen and human pathogenic microbial load resulting in less waste to molding, spoilage, and destruction because of pathogenic poisons.

We claim:  
     
         1 . A method of controlling microbial pathogens on living plant tissue comprising treating said plant tissue with a dilute aqueous solution comprising an effective amount of one or more aliphatic C 2 -C 12  peroxycarboxylic acids, and an aliphatic C 3 -C 12  carboxylic acid, wherein the mole ratio of aliphatic carboxylic acid to peroxycarboxylic acid is less than about 3:1.  
     
     
         2 . The method of  claim 1  wherein the plant tissue comprises a seed.  
     
     
         3 . The method of  claim 1  wherein the plant tissue comprises a tuber.  
     
     
         4 . The method of  claim 1  wherein the plant tissue comprises a growing plant.  
     
     
         5 . The method of  claim 1  wherein the plant tissue comprises a cutting.  
     
     
         6 . The method of  claim 1  wherein the plant tissue comprises rooting stock.  
     
     
         7 . The method of  claim 1 , wherein the aqueous solution comprises: 
 (a) at least about 5 parts per million (ppm) of one or more aliphatic C 2 -C 12  peroxycarboxylic acids; and    (b) at least about 0.1 parts per million (ppm) of an aliphatic C 3 -C 12  carboxylic acid.    
     
     
         8 . The method of  claim 7 , wherein the peroxycarboxylic acid is peroxyacetic acid, peroxyoctanoic acid, perglycolic acid, permalonic acid, perlactic acid, peroctanoic acid, perhydroxycaproic acid, perhydroxycaprylic acid, mono-methyl peradipate, monomethyl persuccinate, mono-methyl perglutarate, mono-ethyl peradipate, mono-ethyl persuccinate, mono-ethyl perglutarate, mono-isobutyl peradipate, mono-isobutyl persuccinate, mono-isobutyl perglutarate, or a mixture thereof.  
     
     
         9 . The method of  claim 7 , wherein the aliphatic carboxylic acid is propionic acid, hexanoic acid, heptanoic acid, octanoic acid, decanoic acid, dodecanoic acid or a mixture thereof.  
     
     
         10 . The method of  claim 1 , wherein the aqueous solution comprises: 
 (a) at least about 4 parts per million (ppm) of a C 2 -C 7  peroxycarboxylic acid;    (b) at least about 1 part per million (ppm) of an aliphatic C 8 -C 12  peroxycarboxylic acid; and    (c) at least 0.1 parts per million (ppm) of an aliphatic C 3 -C 12  carboxylic acid.    
     
     
         11 . The method of  claim 10 , wherein said C 2 -C 7  peroxycarboxylic acid is peroxyacetic acid, mono-methyl persuccinate, mono-methyl perglutarate, mono-methyl peradipate, mono-ethyl persuccinate, mono-ethyl perglutarate, or a mixture thereof.  
     
     
         12 . The method of  claim 10  wherein said C 8 -C 12  aliphatic peroxycarboxylic acid is peroxyoctanoic acid, mono-ethyl peradipate, mono-isobutyl peradipate, mono-isobutyl persuccinate, mono-isobutyl perglutarate, or a mixture thereof.  
     
     
         13 . A method for controlling microbial pathogens on living plant tissue comprising: 
 (a) diluting in an aqueous liquid a concentrate comprising: 
 (i) about 0.1 to 25 wt-% of one or more aliphatic C 2 -C 12  peroxycarboxylic acids; and  
 (ii) about 0.01 to 30 wt-% of an aliphatic C 3 -C 12  carboxylic acid to form a solution; and  
   (b) contacting said plant tissue with said solution, wherein the mole ratio of aliphatic carboxylic acid to peroxycarboxylic acid is less than about 3:1.    
     
     
         14 . The process of  claim 13 , wherein the C 2 -C 12  peroxycarboxylic acid is peroxyacetic acid, peroxyoctanoic acid, mono-methyl persuccinate, mono-methyl perglutarate, mono-methyl peradipate, mono-ethyl persuccinate, mono-ethyl perglutarate, mono-ethyl peradipate, mono-isobutyl peradipate, mono-isobutyl persuccinate, mono-isobutyl perglutarate, or a mixture thereof.  
     
     
         15 . The process of  claim 13 , wherein the aliphatic carboxylic acid is propionic acid, hexanoic acid, heptanoic acid, octanoic acid, decanoic acid, dodecanoic acid or a mixture thereof.  
     
     
         16 . The process of  claim 13 , wherein the concentrate further comprises about 1 to 15 wt-% of a hydrotrope.  
     
     
         17 . The process of  claim 16 , wherein the hydrotrope is n-octanesulfonate, a xylene sulfonate, an alkylbenzene sulfonate, an alkyl naphthalene sulfonate, an amine oxide, an alcohol ethoxylate, or a mixture thereof.  
     
     
         18 . The process of  claim 13 , wherein the concentrate further comprises a chelating agent.  
     
     
         19 . The process of  claim 18 , wherein the chelating agent is 1-hydroxyethylidene-1,1-diphosphonic acid.  
     
     
         20 . The method of  claim 13 , wherein the concentrate comprises: 
 (a) about 0.1 to 25 wt-% of a C 2 -C 7  peroxycarboxylic acid;    (b) about 0.1 to 20 wt-% of a C 8 -C 12  aliphatic peroxycarboxylic acid; and    (c) about 0.01 to 30 wt-% of an aliphatic C 3 -C 12  carboxylic acid.    
     
     
         21 . The method of  claim 20 , wherein the C 2 -C 7  peroxycarboxylic acid is peroxyacetic acid, mono-methyl persuccinate, mono-methyl perglutarate, mono-methyl peradipate, mono-ethyl persuccinate, mono-ethyl perglutarate, or a mixture thereof.  
     
     
         22 . The method of  claim 20 , wherein the C 8 -C 12  peroxycarboxylic acid is peroxyoctanoic acid, mono-ethyl peradipate, mono-isobutyl peradipate, mono-isobutyl persuccinate, mono-isobutyl perglutarate, or a mixture thereof.  
     
     
         23 . A method for controlling microbial pathogens on living plant tissue comprising: 
 (a) diluting in an aqueous liquid a concentrate comprising: 
 (i) about 1 to 20 wt-% of a C 2 -C 7  peroxycarboxylic acid; and  
 (ii) about 0.1 to 20 wt-% of an aliphatic C 8 -C 12  peroxycarboxylic acid;  
 (iii) about 5 to 40 wt-% of a C 2 -C 7  carboxylic acid;  
 (iv) about 1 to 20 wt-% of an aliphatic C8-C 1-2  carboxylic acid;  
 (v) about 1 to 30 wt-% of hydrogen peroxide; and  
 (vi) about 0.01 to 30 wt-% of another C 3 -C 12  aliphatic carboxylic acid to form a solution, wherein the mole ratio of aliphatic carboxylic acid to peroxycarboxylic acid is less than about 3:1; and  
   (b) contacting said plant tissue with said solution.    
     
     
         24 . The process of  claim 23 , wherein the C 2 -C 7  peroxycarboxylic acid is peroxyacetic acid, mono-methyl persuccinate, mono-methyl perglutarate, mono-methyl peradipate, mono-ethyl persuccinate, mono-ethyl perglutarate, or a mixture thereof.  
     
     
         25 . The process of  claim 23 , wherein the C 8 -C 12  aliphatic peroxycarboxylic acid is peroxyoctanoic acid, mono-ethyl peradipate, mono-isobutyl peradipate, mono-isobutyl persuccinate, mono-isobutyl perglutarate, or a mixture thereof.  
     
     
         26 . The process of  claim 23 , wherein the C 3 -C 12  aliphatic carboxylic acid is propionic acid, hexanoic acid, heptanoic acid, octanoic acid, decanoic acid, dodecanoic acid or a mixture thereof.  
     
     
         27 . The process of  claim 23 , wherein the concentrate further comprises about 1 to 15 wt-% of a hydrotrope.  
     
     
         28 . The process of  claim 27 , wherein the hydrotrope is n-octanesulfonate, a xylene sulfonate, an alkyl benzene sulfonate, an alkyl naphthalene sulfonate, an amine oxide, an alcohol ethoxylate, or a mixture thereof.  
     
     
         29 . The process of  claim 23 , wherein the concentrate further comprises a chelating agent.  
     
     
         30 . The process of  claim 29 , wherein the chelating agent is 1-hydroxyethylidene-1,1-diphosphonic acid.  
     
     
         31 . A method of growing at least one plant on a hydroponic substrate in a hydroponic liquid supply medium to produce usable fruit or vegetable products with reduced microbial contamination, the method comprising: 
 (a) establishing growing and living plant tissue in the hydroponic substrate;    (b) contacting the living plant tissue, the hydroponic substrate and the hydroponic liquid with a dilute aqueous solution comprising an effective amount of one or more C 2 -C 12  percarboxylic acids and an aliphatic C 3 -C 12  carboxylic acid, wherein the mole ratio of aliphatic carboxylic acid to peroxycarboxylic acid is less than about 3:1; and    (c) harvesting an improved product.    
     
     
         32 . The method of  claim 31  wherein the percarboxylic acid is peracetic acid.  
     
     
         33 . The method of  claim 31  wherein the aliphatic carboxylic acid comprises heptanoic acid, octanoic acid, decanoic acid, dodecanoic acid or a mixture thereof.  
     
     
         34 . The method of  claim 31  wherein the percarboxylic acid comprises a mixture of a C 2 -C 7  and a C 8 -C 12  aliphatic percarboxylic acid.  
     
     
         35 . The method of  claim 31  wherein the aqueous solution comprises about 4 to 100 parts per million of a C 2 -C 7  percarboxylic acid and about 1 to about 100 parts per million of an aliphatic C 8 -C 12  percarboxylic acid.  
     
     
         36 . The method of  claim 31  wherein the percarboxylic acid comprises a mixture of peroxyacetic acid and peroxyoctanoic acid.  
     
     
         37 . The method of  claim 31  wherein the aqueous solution comprises about 5 to 1000 parts per million of an aliphatic C 3 -C 12  carboxylic acid.  
     
     
         38 . The process of  claim 31  wherein the living tissue comprises a germinating seed.  
     
     
         39 . The method of  claim 31  wherein the living tissue comprises a growing tuber.  
     
     
         40 . The method of  claim 31  wherein the plant tissue comprises a growing dicotyledon.  
     
     
         41 . The method of  claim 31  wherein the plant tissue comprises a growing monocotyledonis plant.  
     
     
         42 . The method of  claim 31  wherein the living tissue comprises a plant cutting.  
     
     
         43 . The method of  claim 31  wherein the plant tissue comprises rooting stock and a graft.