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Grower Solutions Magazine
Lefroy Valley

Grower Solutions - Dec 2001

iquicop is a liquid copper formulation with no crystalline nature. As a result of this, Liquicop does not cause any wear on your spray equipment, is easy to measure and does not leave your tractor and driver covered in blue powder.

Why is liquid better than crystalline copper?

Crystalline copper (copper oxychloride, copper hydroxide) is not very soluble, and at best forms a suspension of small crystals. These crystals are then pumped through your impeller, filters and nozzles and cause excessive wear. The droplets land on the leaf and start drying down. As this happens, the suspended micro- crystals act as seed crystals for the small amount of soluble copper to re- crystalise onto. This results in relatively large crystals settling loosely on the leaf surface. The same can be said for the other “liquid” coppers available on the Australian market which are simply crystalline copper in suspension.

Liquicop, on the other hand, is never a crystal - in fact it is manufactured from a solid piece of copper which is brought into the solution by electrolysis. Once it is mixed (no pre- mixing required) and pumped smoothly through your spray- rig, the droplet starts drying down on the leaf. There are no seed crystals so the copper starts to crystalise onto the leaf surface (trichomes and cuticle). Texture of various leaf surfaces provide anchorage for Liquicop e. g. A: Trichomes (hairs) on Kalanchoe leaf, B: Onion cuticle

These crystals are now the same as crystaline copper, but are firmly attached to the leaf, and coat the leaf surface, rather than as lumps of copper on the leaf. Which would you rather use to keep bugs out of your house - insect screen or burglar bars? The finer the gaps in your defence, the less chance of a successful infiltration.



Copper hydroxide on a leaf surface. Note the size of crystals and how they concentrate and leave gaps on the leaf (800 times magnification).

Liquicop on the leaf surface. Note fine crystal formation and even distribution over the surface (800 times magnification).

The Liquicop crystals are also much smaller (i. e. their surface area to mass ratio is higher) and have more surface area for re- dissolving whenever there is irrigation or dew - high risk periods for fungal and bacterial infection. The better adhesion of crystals to the leaf does however extend withholding periods.

Why is pH important with copper sprays?

The optimum pH for all copper sprays is pH 6- 7. With crystalline coppers this is less critical as so little copper is in the solution that phytotoxicity is minimal, but so is the effectiveness. With Liquicop which is 100% soluble, pH is more important. As you decrease the pH, the risk for burning increases - as you increase the pH the formation of copper oxide increase. Copper oxide crystalises on the leaf but is almost completely insoluble, leaving you no residual protection.

Mixing instructions 

Two factors are important:

1.  Correct pH before adding any other chemicals.

2.  Add Liquicop last to the mix. A fully tested compatibility list is available. Preferably check the pH prior to adding Liquicop to complicated cocktails.

How does copper control disease? 

Liquicop interferes with enzyme function and protein synthesis in pathogens.    

Other benefits:
1. Lower concentration of copper in Liquicop reduces the possibility of copper toxicity in the leaf or in the soil.

2. Easily dosed by volume.

3. No unsightly blue residues on crops due to more even distribution.

4. Safe for use in high concentration aerial applications as long as adequate coverage is achieved.

5. Liquicop is environmentally compatible, and has no effect on pollinators.

6. Liquicop’s formulation should not cause flower drop in sensitive crops, but should preferably not be applied at peak flowering periods.

By: Steve Ansermino

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