1. Understanding how Coppers Work TIM TORR EASTPACK
PSA
Understanding how Coppers Work
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2. How does Copper work Protective bactericides
Must be applied before significant bacterial innoculum arrives.
Not systemic – no re-distribution will occur post application.
Require moisture to be present on plant surface to be active.
Copper particles gradually desintegrate releaseing Cu+ and Cu++ ions.
Cu++ ions are absorbed by bacteria and destroy the enzyme system in the pathogens.
Copper is most effective on those diseases that need free water present to develop
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3. How does Copper work
Cu+ and Cu++ ions are pathogen killers in water on the leaf
- Leaf surfaces are wetter than the atmosphere, this is the “boundary layer effect”.
- Plants excrete acids on to leaf surface.
- pH below is required to produce Cu++ and Cu+ ions
Too rapid release of these ions causes plant damage!
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4. Leaf chemistry pH 5-7 Tim Torr
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5. Leaf chemistry pH 5-7 Tim Torr
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6. Bactericidal effect I Tim Torr
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7. Bactericidal effect II
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8. Bactericidal effect III
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9. Copper Bactericides There are five basic types of Copper compounds
Copper oxychloride
Copper hydroxide (Kocide , Champ etc…)
Tribasic copper sulphate (Green and Blue Coppers)
Copper ammonium complexes (dark blue liquids, e.g. Liquicop)
Cuprous oxide (Red coppers, e.g. Nordox)
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10. Copper Bactericides They have different characteristics.
Important characteristics are
Solubility
and
Particle size
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11. Solubility Soluble Coppers In-Soluble Coppers
Erode faster and require more frequent applications
In-Soluble Coppers
Release a lasting supply of Cu++ and Cu+ ions in the acidic environment of the plant surface
Require less frequent re-application
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12. Solubility Least soluble Most soluble Solubility is a factor of
Cuprous oxide Oxychlorides Hydroxides Copper sulphate
Least soluble Most soluble
Solubility is a factor of
Particle size
Temperature and moisture
Form and formulation
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13. Particle Size
The smaller the particle size the greater the number of particles per gram of copper applied.
This dramatically improves the coverage of the product on the plant.
The smaller the particle size the greater the surface area per gram of copper applied.
This means that there is far more surface area available to react and release Cu++ and Cu+ ions
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14. The effect of small particle size on coverage

15. Particle Size
Smaller particle size gives greater retention of the product on the plant surface because there is a greater proportion of the particle in direct contact with the plant surface relative to their weight.
Copper product particle retention is influenced by
Rainfall, direct dislodgement or solubilisation by the water present.
Wind events, can dislodge the larger particles.
Rubbing against other parts of the plant
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16. Loss of Copper product from the leaf surface of Gold kiwifruit leaves during a simulated rainfall event.
The remaining product is becoming more persistent as the larger particles disappear.
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17. Cupric hydroxide Cu(OH)2 - Crystal structure - 2.5 microns av.
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18. Cuprous oxide Cu2O (Nordox) - Fine cubes - less than 1.0 microns av
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19. Copper Phytotoxicity
Too many Copper ions at any one time can cause damage to the plant.
Darkening of the leaf veins
Dead spots on the leaves
Marking on the Fruit
Thickening of the leaf cuticle
Loss of vigor of shoots
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22. Copper Phytotoxicity
Can be caused by anything that results in a large number of Copper ions being absorbed by the plant…
Slow drying conditions
pH of spraying solution is too low (below 6.5)
Form of Copper is too soluble e.g. Copper sulphate
Product rate is too high
Impurities in the sprayed product e.g. heavy metal contaminants or chlorides
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23. Summary Coppers Are not systemic
Release copper ions on the plant surface
Copper ions are the real “active ingredient”
Coppers need to be applied before the bacteria arrives
Can be very persistent on the plant surface
Small particle size is more effective
Small particle size is more persistent
Insoluble Copper formulations last longer
Need to be applied in good drying conditions
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24. Any Questions ?
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