Bordeaux mixture (also called Bordo Mix) is a mixture of copper(II) sulphate (CuSO4) and quicklime (CaO)used as a fungicide. It is used in vineyards, fruit-farms and gardens to prevent infestations of downy mildew, powdery mildew and other fungi. It is sprayed on plants as a preventive treatment; its mode of action is ineffective after a fungus has become established. It was invented in the Bordeaux region of France in the late 19th century. If it is applied in large quantities annually for many years, the copper in the mixture eventually becomes a pollutant. As such its sale and use is illegal in Great Britain and most of the European Union. Despite this, it has been promoted as an ‘organic’ pesticide.
Bordeaux mixture—a combination of copper sulfate, lime, and water—is an effective fungicide and bactericide that has been used for decades to control diseases of fruit and nut trees, vine fruits, and ornamental plants. These natural minerals, when mixed in the correct order, provide long-lasting protection to plants against diseases.
The ability of Bordeaux mixture to adhere to plants in rainy weather makes it an excellent choice for a winter fungicide. Applying Bordeaux after trees break dormancy generally isn’t recommended, because it can injure leaves.
Among Bordeaux’s many uses are applications in fall and winter to manage:
- Fire blight on pears and apples;
- Leaf curl and shot hole on peaches and nectarines;
- Downy mildew and powdery mildew on grapes;
- Peacock spot on olives;
- Walnut blight on walnut; and
- Black spot on roses.
The following precautions are needed during preparation and application of Bordeaux mixture.
- The solution should be prepared in earthen or wooden or plastic vessels. Avoid using metal containers for the preparation, as it is corrosive to metallic vessels.
- Always copper sulphate solution should be added to the lime solution, reverse the addition leads to precipitation of copper and resulted suspension is least toxic.
- Bordeaux mixture should be prepared fresh every time before spraying. In case, the mixture has to be stored for a short time or a day, jaggery can be added at the rate of 100kg/100 litres of the mixture.
- Bordeaux mixture is sometimes phytotoxic to apples, peaches, new shoots/leaf.
Advantages of Bordeaux mixture
- Very easy and can prepared by farmers themselves.
- Can act as fungicide, bactericide and algaecide.
- Applicable to tomato, potato, chilli, other vegetables, fruits (orange, lime, lemon), beetel vine, ginger, flower and ornamental plant diseases such as foot rot, stem rot, leaf spot, leaf blight, anthracnose, canker, damping off, black spot, downy mildew, late and early blight etc.
- The chemicals required for this is copper sulphate and lime which is easily available in the market.
- All the diseases controlled by copper based fungicides such as leaf spot, blight diseases can be controlled by this.
- It is less toxic to human as compare to other commercial fungicides.
Modec of action
Bordeaux mixture achieves its effect by means of the copper ions (Cu2+) of the mixture. These ions affect enzymes in the fungal spores in such a way as to prevent germination. This means Bordeaux mixture must be used preventively, before the fungal disease has struck.
Thorough coverage of the spray on the plants is necessary. The Bordeaux spray continues to adhere well to the plant during rain, though in the long term it is washed off by rain. Commonly in practice, it is applied just once a year, in the wintertime.
Prices of Bordeaux Mixture
$1,700.00-$2,100.00/ Metric Ton.