What is Coptyzin, and how does it work to control Psa in Kiwifruit?


COPTYZIN is a copper bactericide for the control of Psa in Kiwifruit.

Active Ingredient: 95 g/L copper (Cu), chelated by tetraethylene pentamine (TEPA) in the form of a soluble concentrate.

Coptyzin also contains 5 g/L of zinc (Zn), chelated by triethylene tetramine (TETA)

Key reasons to use Coptyzin

  • Has full label claim registration for the control of Psa
  • Completely soluble concentrate with unique chemistry
  • Efficacy with less elemental copper
  • Evenly spread copper that adheres to the leaf surface quickly but is also systemic
  • No adjuvants required
  • Can be mixed with most other sprays
  • Coptyzin can be applied throughout the year (but avoid spraying on open flowers).
  • Being a liquid formulation, it is easy to measure the required dosage.
  • Coptyzin won't leave stains on your sprayer.

The unique chemistry of Coptyzin:

The TEPA chelating agent is a long chain of polyamines and polyethyleneimines which are able to form very stable chelates. The high stability constant of 22.4 (logarithmic value) allows the CuTEPA to release the copper ions gradually over a period of time.

Copper TEPA Chelate

The CuTEPA chelate is not only highly soluble, but it is also positively charged.

Leaves have negative charges on the outside (they have a cation exchange capacity CEC) and therefore they will retain cations and positively charged molecules such as the CuTEPA chelate in Coptyzin, thereby increasing the copper concentration on the outside of the leaves.

Coptyzin covers the leaves with copper a lot more evenly. It creates a very fine film of copper, (almost up to molecular level) affording protection using a much smaller dosage compared to other copper sprays.

For example, Coptyzin sprayed at 1.5L per Ha in 1000L of water will deliver 142.5 grams of elemental copper. Compare that to Nordox at 37.5 grams in 100L water, the copper content at 1000L water per Ha is 281.25 grams (almost double that of Coptyzin ), and Kocide Opti at the rate of 70 grams per 100L of water delivers 210 grams of copper per Ha at the water rate of 1000L per Ha. This comparative information has been sourced from the Zespri Crop Protection Programme.

In the context of rising copper levels in the soil after years of applications to control Psa, the above differences become significant over time. Coptyzin is better for the environment and easier on the vines.

Coptyzin is active at the surface of the leaves but it is also gradually absorbed by the plant. It is mobile through the xylem sap and also via the phloem without creating phytotoxicity when used at label dosage rates.

Left: a lush and healthy canopy using TEPA chelated Cu prevention and kiwifruit vine nutrition program.

Right: an orchard using other forms of treatment for Psa management and prevention.

Coptyzin:

  • Stimulates the production of lignins, increasing the physical resistance of the cell wall (essentially of the exterior cells)
  • Stimulates the production of phytoalexins. These are non-specific defence molecules that plants produce and they have an influence on the germination of spores, the growth of fungi and the development of bacteria.
  • The TEPA-chelated copper within Coptyzin enables the copper to be exchanged with, and integrated into other SAR-proteins, that protect the plant (SAR = Systemic Acquired Resistance).

Coptyzin also contains Zinc

Zinc works together with other nutrients to detoxify free radicals. Therefore it reduces the potential damage to cells and it slows down the plant's ageing process. Zinc also ensures the stability and integrity of the cell membranes.
The Zinc contained within Coptyzin will help the plant to maintain its integrity and to recover from possible damage provoked by bacterial attacks. Zinc also stimulates the production of auxins, which will help to avoid slowdowns in growth, and if necessary it will help restart growth.

Dosage and use of Coptyzin

Refer to the Coptyzin label.