How to prepare the Bordeaux mixture
The Bordeaux mixture is an anticryptogamic used for some harmful diseases of plants (above all the peronospora of the tomato). It was already used in Roman times, as a compound based on copper and calcium, diluted in water.
Bordeaux mixture is a contact anticryptogamic, based on copper (which is a metal that damages the cell walls of fungi that damage many crops.
The Bordeaux mixture is a product based on copper and, therefore, useful for treating fake diseases that attack roots, leaves and fruits of our agricultural products.
Being able to prepare the Bordeaux mixture “on the farm” we avoid the addition of coformulati (often harmful) that we would give to our plants (and therefore to us through feeding).
To prepare the Bordeaux mixture we need three simple elements:
Copper sulfate (CuSO4), purchased in powder form (to facilitate dissolution), but if not available also in flakes.
Lime, preferably alive, i.e. calcium oxide, CaO. If you can not find it, you can also use the lime turned off or hydrated, ie calcium hydroxide, Ca (OH) 2, deriving from the extinguishing reaction involving the quicklime: CaO + H2O → Ca (OH) 2.
The proportions that we must use for the mixture are: 1 kg of copper sulphate and 1 kg of lime per 100 liters of water.
The mixture should be prepared in non-metallic containers (one of 20 and one of 150 liters, or identical proportions on different quantities and therefore with containers of different capacities) and mixed with the help of a wooden stick.
At this point dissolve 1kg of copper sulfate in 10 liters of water in our 20 liter container. Let’s make sure that the mixture dissolves completely, leaving no residue (if the copper is in flakes let’s put it a day before in water to facilitate its melting).
Then dissolve the kg of lime in the remaining 90 liters of water, in the 150 liter container. Now mix them together, adding the copper sulphate to the lime mixture, always in this order and then mix to mix everything.
The Bordeaux mixture should be used within the following day in order not to make it lose its effectiveness. The preventive treatment must be carried out before it rains in order to counteract the development of the mushrooms beforehand and by acting (especially on the leaves) from the bottom upwards. It is advisable not to use this product for soft tissues and in the presence of flowering as it contrasts the setting.
Another warning is not to absolutely abuse these products because the copper (heavy metal) present in it if it accumulates in the ground, inhibits and depresses the microbial activities useful for the synthesis processes of the humus.
It should be avoided to reach the limit of about 6kg / Ha per year, which, inter alia, is the legal limit allowed.