Know Your Copper Fungicide
A new broad spectrum fungicide has been proven to kill different fungi and bacteria in ornamentals.
Fungicides have been used for more than 400 years from as simple as a brine solution, which was used for cereal seed treatment, to the introduction of very complex organic chemical compounds in the earlier half of the 20th century. There are different classes of fungicides that are classified according to their chemical structure. One of them is copper-based fungicides or copper fungicides. It has been used to protect crops after the ‘accidental’ discovery of the Bordeaux mixture by Pierre-Marie-Alexis Millardet in the late 1800s.
Disease control with the use of a copper based fungicide is done by disrupting the functions of the cellular proteins of fungi and bacteria. This is because when cupric ions are released in the presence of moisture, it destroys the secondary and tertiary structures (denaturation) of these proteins upon contact. Once these proteins are denatured, its functions are lost.
Copper is an essential micro element needed by plants. It is an important component of proteins found in some enzymes which are involved in regulating some biochemical reactions. Copper is also responsible for chlorophyll formation and promotes seed production and formation. Excess concentration especially on the roots can largely affect as growth and morphology.
In the Philippines, the common copper based fungicides are copper oxychloride, copper hydroxide and cuprous oxide. Nordox 50 WP is the only copper fungicide in the market with cuprous oxide as its active ingredient. It is a broad spectrum fungicide used not only to kill different fungi but bacteria as well. It also breaks the resistance of these pathogens wherein it disrupts the disease build up in an area where there is a history of infection. Nordox 50 WP is produced in Norway by NORDOX AS, the worldleading producer of superior cuprous oxide for agrochemical use. It is super micronized with particles slightly larger than 1 micron that is why it is very effective in preventing and controlling the development of fungi.
Particle size and solubility
With copper fungicides, the effectivity to control fungi and bacteria is not determined by the number of applications per area or how many grams of active ingredient were applied, rather it depends on how long it retains on the plant surface. The longer it is retained the more effective it is in controlling pathogens.
The particle size of Nordox 50 WP is only 1.2 microns while copper hydroxide and copper oxychloride is 1.8 and 2.5 microns, respectively. Given its fine particle size, it gives a more uniform dispersion when mixed in water as compared to other fungicides. With even dispersion, the active ingredient is not settling at the bottom of the sprayer giving a more uniform application from the very start of application up to the last drop of the mixture. Since Nordox 50 WP is very fine, it has higher surface contact, so it can adhere longer on the plant surface giving better protection. This is the other two copper fungicides which have tendencies to settle and give an inconsistent mixture and can be easily removed by rain and wind when applied on leaves. The other copper fungicides with larger particles are easily removed from the leaf surface by rain or wind and then accumulate in the soil injuring the roots which adversely affects plant growth.
Another criterion to consider aside from the size of the particle is the solubility of the copper fungicides. This is because solubility determines the release rate of cupric ions. The copper in Nordox 50WP are more insoluble than the two copper fungicides. Being more insoluble, it provides a slower, controlled release of cupric ions on the leaf surface providing the plant longer, more cost efficient protection compared with other fungicides. If the copper source is very soluble, there is a tendency of releasing too many cupric ions that can damage the leaf.
Nordox 50WP is the cheapest copper fungicide in the market. It comes in a 1 kilogram box with a suggested retail price of Php600.00 and a recommended rate of 2 grams per load. Each load would cost about Php11.00 to Php17.00 depending on the rate. Although its price is almost the same as the other fungicides, the cost per knapsack load is cheaper and you save about 9% as compared to copper hydroxide and 118% as compared to copper oxychloride. These savings can be doubled or tripled especially during rainy season because with other fungicides, there is a need for a sticker and reapplication since these can be easily washed off by rain. Reapplication means added production costs. With Nordox 50WP, once you have applied it, you are certain that it stays there to give your plant better protection against diseases caused by fungi and bacteria.