# US 12,108,756 B2 · Photodynamic method of inhibiting growth of a microbial plant pathogen

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- Number: US 12,108,756 B2
- Document ID: US12108756B2
- Status: Granted
- Kind: B2
- Application number: 17/278,657
- Filed: 2019-09-24
- Published: 2022-04-14
- Granted: 2024-10-08
- Earliest claimed: 2019-09-24
- Assignees: TDA Research, Inc.
- Applicants: TDA Research, Inc
- Inventors: Christopher Brian France; William Bell
- Web page: https://patentgrep.com/patent/US12108756B2

## CPC

- A01N 25/00: Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application {, e.g. seed treatment or sequential application}; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
- A01N 59/20: Copper
- A01N: PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF (preservation of food or foodstuff A23); BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES (preparations for medical, dental or toiletry purposes which kill or prevent the growth or proliferation of unwanted organisms A61K); PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS

## Abstract

We describe methods and materials for inhibiting the growth of a microbial pathogen of a plant. The method comprises the steps of applying to the plant a combination of a dye-bearing compound which is a reactive oxygen species photosensitizer; and a copper compound, which increases the microbial lethality of the dye-bearing compound towards the microbial pathogen; and exposing the plant to light to activate the combination of the dye-bearing compound and the copper compound and inhibiting growth of a microbial pathogen of a plant. The combination of the dye-bearing compound and the copper compound may result in a synergistic ability to reduce the growth of a plant pathogen.

## Claims

### Claim 1

A method for synergistically inhibiting growth of a microbial pathogen of a plant, comprising:
applying to the plant a combination comprising:
a dye-bearing compound which is a reactive oxygen species photosensitizer, wherein the dye-bearing compound is provided at a concentration between about 1 and 100 ppm on a mass basis; and
a copper compound to increase the microbial lethality of the dye-bearing compound towards the microbial pathogen, wherein the copper compound is provided at a concentration between about 3.98 and 39.8 ppm of copper on a mass basis; and
exposing the plant to light to activate the combination of the dye-bearing compound and the copper compound and inhibiting growth of a microbial pathogen of a plant;
wherein the copper compound and the dye-bearing compound are provided in amounts that are synergistically effective to inhibit growth of the microbial pathogen.

### Claim 2 (depends on 1)

The method of claim 1, wherein the copper compound is a copper salt, and wherein the copper salt and the dye-bearing compound are provided in amounts that are synergistically effective to inhibit growth of the microbial pathogen, wherein said combination increases microbial pathogen log kill by at least 1 order of magnitude, compared to the log kill that is expected based on an additive efficacy model, wherein the additive efficacy model determines the expected percent kill as calculated by the expression, P=X+Y(100−1)/100, wherein P is the expected percent kill of the pathogen using the combination of the reactive oxygen species photosensitizer and the copper salt, X is the percent kill of the pathogen when the reactive oxygen species photosensitizer is used alone, and Y is the percent kill of the pathogen when the copper salt is used alone.

### Claim 3 (depends on 2)

The method of claim 2, wherein the dye-bearing compound is selected from the group consisting of a riboflavin, a derivatized riboflavin, a lumichrome, a derivatized lumichrome, a curcumin, a fluorescein, an eosin Y, an erythrosine, a flavin-containing compound and a rose bengal B.

### Claim 4 (depends on 3)

The method of claim 3, wherein the dye-bearing compound is riboflavin.

### Claim 5 (depends on 1)

The method of claim 1, wherein the copper compound is a copper salt selected from the group consisting of a copper (II) sulfate, a copper (II) nitrate, a copper hydroxide, a copper carbonate, a copper chloride, a copper oxide, and a copper bromide.

### Claim 6 (depends on 1)

The method of claim 1, further comprising applying an ascorbate to the plant to increase the microbial lethality of said combination towards the microbial pathogen.

### Claim 7 (depends on 5)

The method of claim 5, wherein the dye-bearing compound is provided at a concentration between about 5 and 50 ppm on a mass basis.

### Claim 8 (depends on 1)

The method of claim 1, wherein exposing the plant to light comprises exposing the plant to natural light.

### Claim 9 (depends on 1)

The method of claim 1, wherein exposing the plant to light comprises exposing the plant to artificial light.

### Claim 10 (depends on 1)

The method of claim 1, wherein said combination is applied to the plant by at least one of soil drenching, pipetting, irrigation, spraying, listing, sprinkling, pouring.

### Claim 11 (depends on 1)

The method of claim 1, wherein the microbial pathogen comprises either a bacterial pathogen, a cyanobacterial, an algal, a fungal pathogen, or a viral pathogen.

### Claim 12 (depends on 1)

The method of claim 1, wherein the plant is a non-woody crop plant, a woody plant, a turfgrass, a fruit-bearing tree, a nut-bearing tree, or an ornamental plant.

### Claim 13 (depends on 1)

The method of claim 1, wherein said combination further comprises at least one agriculturally acceptable adjuvant.

### Claim 14 (depends on 13)

The method of claim 13, wherein the agriculturally acceptable adjuvant is selected from the group consisting of a surfactant, a penetrant, a wetting agent, a spreading agent, a humectant and an emulsifier.

### Claim 15 (depends on 1)

The method of claim 1, wherein the copper compound is a copper salt, and wherein the dye-bearing compound and the copper salt are applied simultaneously to the plant.

### Claim 16 (depends on 1)

The method of claim 1, wherein the copper compound is a copper salt, and wherein the dye-bearing compound and the copper salt are applied sequentially to the plant.

### Claim 17 (depends on 1)

The method of claim 1, wherein the copper compound is a copper salt, and wherein the copper salt is used at a concentration below 39.8 ppm of copper on a mass basis to avoid unwanted damage to the plant or the environment.

### Claim 18 (depends on 1)

The method of claim 1, wherein the copper compound is a copper salt, and wherein the dye-bearing compound and the copper salt are suitable for organic agricultural practices.

### Claim 19 (depends on 1)

The method of claim 1, wherein the copper compound is a copper salt, and further comprising applying to the plant an ascorbic acid and a sodium bicarbonate to react with the copper salt to generate a reactive oxygen species.

### Claim 20 (depends on 2)

The method of claim 2, further comprising applying to the plant an ascorbate salt to react with the copper salt to generate a reactive oxygen species.

### Claim 21 (depends on 1)

The method of claim 1, wherein the dye-bearing compound which is a reactive oxygen species photosensitizer is selected from the group consisting of a riboflavin, a derivatized riboflavin, a lumichrome, a derivatized lumichrome, a curcumin, a fluorescein, an eosin Y, an erythrosine, and a rose bengal B; and wherein the copper compound is a copper ion-bearing organic complex to increase the microbial lethality of the dye-bearing compound towards the microbial pathogen.

### Claim 22 (depends on 21)

The method of claim 21, wherein the copper ion-bearing organic complex is provided in an amount sufficient to increase microbial pathogen growth inhibition compared to the microbial pathogen growth inhibition of the reactive oxygen species photosensitizer alone.

### Claim 23 (depends on 22)

The method of claim 22, wherein the copper ion-bearing organic complex and the dye-bearing compound are provided in amounts that are synergistically effective to inhibit growth of the microbial pathogen, wherein said combination increases microbial pathogen growth inhibition to an extent that is greater than the sum of the microbial pathogen growth inhibition of the reactive oxygen species photosensitizer and the copper ion-bearing organic complex when each is used alone.

### Claim 24 (depends on 22)

The method of claim 22, wherein the copper ion-bearing organic complex and the dye-bearing compound are provided in amounts that are synergistically effective to inhibit growth of the microbial pathogen, wherein said combination increases microbial pathogen log kill by at least 1 log, or at least 1 order of magnitude, compared to the log kill that is expected based on an additive efficacy model, wherein the additive efficacy model determines the expected percent kill as calculated by the expression, P=X+Y(100−1)/100, wherein P is the expected percent kill of the pathogen using the combination of the reactive oxygen species photosensitizer and the copper ion-bearing organic complex, X is the percent kill of the pathogen when the reactive oxygen species photosensitizer is used alone, and Y is the percent kill of the pathogen when the copper ion-bearing organic complex used alone.

### Claim 25 (depends on 21)

The method of claim 21, wherein the dye-bearing compound is riboflavin.

### Claim 26 (depends on 21)

The method of claim 21, wherein the copper ion-bearing organic complex is selected from the group consisting of a copper ethanolamine, a copper EDTA, a copper ion complexed to a crown ether, and a copper ion complexed to polyethylene glycol.

### Claim 27 (depends on 21)

The method of claim 21, wherein said combination further comprises at least one agriculturally acceptable adjuvant.

### Claim 28 (depends on 27)

The method of claim 27, wherein the agriculturally acceptable adjuvant is selected from the group consisting of a surfactant, a penetrant, a wetting agent, a spreading agent, a humectant and an emulsifier.

### Claim 29 (depends on 21)

The method of claim 21, wherein the dye-bearing compound and the copper ion-bearing organic complex are applied simultaneously to the plant.

### Claim 30 (depends on 21)

The method of claim 21, wherein the dye-bearing compound and the copper ion-bearing organic complex are applied sequentially to the plant.

### Claim 31 (depends on 21)

The method of claim 21, wherein the copper ion-bearing organic complex is used at a concentration below 100 ppm on a mass basis to avoid unwanted damage to the plant or the environment.

### Claim 32 (depends on 21)

The method of claim 21, wherein the dye-bearing compound and the copper ion-bearing organic complex are suitable for organic agricultural practices.

### Claim 33 (depends on 24)

The method of claim 24, further comprising applying to the plant an ascorbic acid and a sodium bicarbonate to react with the copper salt to generate a reactive oxygen species.

### Claim 34 (depends on 24)

The method of claim 24, further comprising applying to the plant an ascorbate salt to react with the copper salt to generate a reactive oxygen species.