Bordeaux mixture
Overview
 
Bordeaux mixture is a mixture of copper(II) sulfate and slaked lime used as a fungicide
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...

 in vineyards. It is used mainly to control garden, vineyard, nursery and farm infestations of fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

, primarily downy mildew
Downy mildew
Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to Peronosporaceae. In commercial agriculture, they are a particular problem for growers of crucifers, grapes and vegetables that grow on vines...

 which can result from infections of Plasmopara viticola
Plasmopara viticola
Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet conditions release zoospores. Zoospores are splashed by rain into the...

. It was invented in the Bordeaux region of France, where it is known locally as Bouillie Bordelaise.
Encyclopedia
Bordeaux mixture is a mixture of copper(II) sulfate and slaked lime used as a fungicide
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...

 in vineyards. It is used mainly to control garden, vineyard, nursery and farm infestations of fungi
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...

, primarily downy mildew
Downy mildew
Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to Peronosporaceae. In commercial agriculture, they are a particular problem for growers of crucifers, grapes and vegetables that grow on vines...

 which can result from infections of Plasmopara viticola
Plasmopara viticola
Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet conditions release zoospores. Zoospores are splashed by rain into the...

. It was invented in the Bordeaux region of France, where it is known locally as Bouillie Bordelaise. This fungicide has been used for over a century and is still used, although the copper can leach
Leaching (chemical science)
Leaching is the process of extracting minerals from a solid by dissolving them in a liquid, either in nature or through an industrial process. In the chemical processing industry, leaching has a variety of commercial applications, including separation of metal from ore using acid, and sugar from...

 out and pollute streams.

Main uses

As well as its use to control fungal infection on grape vines the mixture is also widely used to control potato blight, peach leaf curl
Taphrina deformans
Taphrina deformans is a fungus and plant pathogen, one of the causal agents of peach leaf curl, the other being a virus.-Life Cycle:T.deformans infects species of the genus Prunus including P. amygdalus and P. persica . Infected leaves develop a whitish bloom as infection progresses...

 and apple scab
Apple scab
Apple scab is a disease to Malus trees, such as apple trees, caused by the ascomycete fungus Venturia inaequalis. The disease manifests as dull black or grey-brown lesions on the surface of tree leaves, buds or fruits. Lesions may also appear less frequently on the woody tissues of the tree. Fruits...

. It is approved for organic use and so is often used by organic gardeners where non-organic gardeners would prefer other controls.

History

In the 19th century there were several outbreaks of vine diseases among the Vitis vinifera
Vitis vinifera
Vitis vinifera is a species of Vitis, native to the Mediterranean region, central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran....

vines of the classicial European wine regions. These outbreaks were caused by pests to which these vines lacked resistance, carried on vines brought to Europe as botanical specimens of American origin. These pests included not only the Great French Wine Blight
Great French Wine Blight
The Great French Wine Blight was a severe blight of the mid-19th century that destroyed many of the vineyards in France and laid to waste the wine industry...

 caused by the aphid
Aphid
Aphids, also known as plant lice and in Britain and the Commonwealth as greenflies, blackflies or whiteflies, are small sap sucking insects, and members of the superfamily Aphidoidea. Aphids are among the most destructive insect pests on cultivated plants in temperate regions...

 Phylloxera vastatrix, but also mildew
Mildew
Mildew refers to certain kinds of molds or fungi.In Old English, it meant honeydew , and later came to mean mildew in the modern sense of mold or fungus....

 and other diseases caused by fungi.
After the downy mildew
Downy mildew
Downy mildew refers to any of several types of oomycete microbes that are obligate parasites of plants. Downy mildews exclusively belong to Peronosporaceae. In commercial agriculture, they are a particular problem for growers of crucifers, grapes and vegetables that grow on vines...

 had struck, botany professor Pierre-Marie-Alexis Millardet
Pierre-Marie-Alexis Millardet
Pierre-Marie-Alexis Millardet was a French botanist and mycologist born in Montmirey-la-Ville.He was a student at the Universities of Heidelberg and Freiberg, and later became a professor of botany at the Universities of Strasbourg , Nancy , and Bordeaux .Millardet is chiefly remembered for his...

 of the University of Bordeaux
University of Bordeaux
University of Bordeaux is an association of higher education institutions in and around Bordeaux, France. Its current incarnation was established 21 March 2007. The group is the largest system of higher education schools in southwestern France. It is part of the Academy of Bordeaux.There are seven...

 was studying the disease in vineyards of the Bordeaux region
Bordeaux wine
A Bordeaux wine is any wine produced in the Bordeaux region of France. Average vintages produce over 700 million bottles of Bordeaux wine, ranging from large quantities of everyday table wine, to some of the most expensive and prestigious wines in the world...

. Millardet then noted that vines closest to the roads did not show mildew, while all other vines were affected. After inquiries, he found out that those vines had been sprayed with a mixture of copper sulfate and lime to deter passersby from eating the grapes, since this treatment was both visible and bitter-tasting. This led Millardet to conduct trials with this treatment. The trials primarily took place in the vineyards of Château Dauzac
Château Dauzac
Château Dauzac is a winery in the Margaux appellation of the Bordeaux region of France. The wine produced here was classified as one of eighteen Cinquièmes Crus in the Bordeaux Wine Official Classification of 1855...

, where he was assisted by Ernest David, Dauzac's technical director. Millardet published his findings in 1885, and recommended the mixture to combat downy mildew.

In France, the use of Bordeaux mixture has also been known as the Millardet-David treatment.

Mode of action

Bordeaux mixture achieves its effect by means of the copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...

s (Cu2+) of the mixture. These ions affect enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

s in the fungal spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...

s in such a way as to prevent germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

. This means that Bordeaux mixture must be used pre-emptively, before the fungal disease has struck.

Preparation

Bordeaux mixture can be prepared using differing proportions of the components. In preparing Bordeaux mixture, the copper sulphate and the lime are dissolved separately in water and then mixed together. Calcium oxide
Calcium oxide
Calcium oxide , commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline crystalline solid at room temperature....

 (burnt lime) and calcium hydroxide
Calcium hydroxide
Calcium hydroxide, traditionally called slaked lime, is an inorganic compound with the chemical formula Ca2. It is a colourless crystal or white powder and is obtained when calcium oxide is mixed, or "slaked" with water. It has many names including hydrated lime, builders lime, slack lime, cal, or...

 (hydrated lime) gives the same end result since an excess of water is used in the preparation.

The conventional method of describing the mixture's composition is to give the weight of copper sulphate, the weight of hydrated lime and the volume of water in that order. The percentage of the weight of copper sulphate to the weight of water employed determines the concentration of the mixture. Thus a 1% Bordeaux mixture, which is typical, would have the formula 1:1:100, with the first "1" representing 1 kg copper sulphate(penta-hydrated), the second representing 1 kg hydrated lime, and the 100 representing 100 litres (100 kg) water. As copper sulphate contains 25% copper, the copper content of a 1% Bordeaux mixture would be 0.25%. The quantity of lime used can be lower than that of the copper sulphate. 1 kg copper sulphate actually requires only 0.225 kg of chemically pure hydrated lime to precipitate all the copper. Good proprietary brands of hydrated lime are now freely available but, as even these deteriorate on storage (by absorbing carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

from the air), a ratio of less than 2:1 is seldom used, which corresponds to a 1:0.5:100 mixture.

Risks

Bordeaux mixture has been found to be harmful to fish, livestock and—due to potential build up of copper in the soil—earthworms.

The chemical began being used by the United Fruit Company throughout Latin America around 1922. The mixture was nicknamed 'perico', or 'parakeet', because it would turn workers completely blue. Many workers would get sick or die of poisoning due to the chemical.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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