Understanding how Coppers Work TIM TORR EASTPACK PSA Understanding how Coppers Work TIM TORR EASTPACK TIM TORR EastPack ph 0272 057 520 tim.torr@eastpack.co.nz

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 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 6.5-7.0 is required to produce Cu++ and Cu+ ions Too rapid release of these ions causes plant damage! Tim Torr

Leaf chemistry pH 5-7 Tim Torr TIM TORR EastPack ph 0272 057 520 tim.torr@eastpack.co.nz

Leaf chemistry pH 5-7 Tim Torr TIM TORR EastPack ph 0272 057 520 tim.torr@eastpack.co.nz

Bactericidal effect I Tim Torr TIM TORR EastPack ph 0272 057 520 tim.torr@eastpack.co.nz

Bactericidal effect II Tim Torr TIM TORR EastPack ph 0272 057 520 tim.torr@eastpack.co.nz

Bactericidal effect III Tim Torr TIM TORR EastPack ph 0272 057 520 tim.torr@eastpack.co.nz

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 Bactericides They have different characteristics. Important characteristics are Solubility and Particle size Tim Torr

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 Tim Torr

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 Tim Torr

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

The effect of small particle size on coverage

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

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. Tim Torr

Cupric hydroxide Cu(OH)2 - Crystal structure - 2.5 microns av. Tim Torr

Cuprous oxide Cu2O (Nordox) - Fine cubes - less than 1.0 microns av Tim Torr

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 Tim Torr

Tim Torr

Tim Torr

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 Tim Torr

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 Tim Torr

Any Questions ? Tim Torr