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PSA. Understanding how Coppers Work TIM TORR EASTPACK. How does Copper work. Protective bactericides Must be applied before significant bacterial innoculum arrives. Not systemic – no re-distribution will occur post application.

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PSA

Understandinghow Coppers Work

TIM TORREASTPACK


How does copper work
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

Tim Torr


How does copper work1
How does Copper work

  • Cu+ and Cu++ ionsare 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 6.5-7.0 is required to produce Cu++ and Cu+ ions

  • Too rapid release of these ions causes plant damage!

Tim Torr







Copper bactericides
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)

Tim Torr


Copper bactericides1
Copper Bactericides

  • They have different characteristics.

  • Important characteristics are

    • Solubility

      and

    • Particle size

Tim Torr


Solubility
Solubility

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

Tim Torr


Solubility1
Solubility

Cuprous oxide Oxychlorides Hydroxides Copper sulphate

Least soluble Most soluble

Solubility is a factor of

  • Particle size

  • Temperature and moisture

  • Form and formulation

Tim Torr


Particle size
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

Tim Torr



Particle size1
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

Tim Torr


Tim Torr


Cupric hydroxide cu oh 2 crystal structure 2 5 microns av
Cupric hydroxide Cu(OH) kiwifruit leaves during a simulated rainfall event.2 - Crystal structure - 2.5 microns av.

Tim Torr


Cuprous oxide cu 2 o nordox fine cubes less than 1 0 microns av
Cuprous oxide Cu kiwifruit leaves during a simulated rainfall event.2O (Nordox) - Fine cubes - less than 1.0 microns av

Tim Torr


Copper phytotoxicity
Copper Phytotoxicity kiwifruit leaves during a simulated rainfall event.

  • 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

Tim Torr


Tim Torr kiwifruit leaves during a simulated rainfall event.


Tim Torr kiwifruit leaves during a simulated rainfall event.


Copper phytotoxicity1
Copper Phytotoxicity kiwifruit leaves during a simulated rainfall event.

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

Tim Torr


Summary
Summary kiwifruit leaves during a simulated rainfall event.

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

Tim Torr


Tim Torr


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