Bordeaux mixture

Bordeaux mixture or Kupferkalkbrühe was the first successful fungicide. This is a suspension of calcined lime (CaO ) in an aqueous copper sulfate solution.

History

Through the importation of vines from America that were considered resistant to phylloxera, the causal agent of downy mildew of grapevine (Plasmopara viticola ) was introduced to southern France in 1878. From there it spread to epidemic proportions throughout France and led to large yield losses in vineyards.

Pierre -Marie Alexis Millardet, professor of botany at the University of Bordeaux, had been instrumental in the importation of American vines. On the search for an effective means against downy mildew, he noticed that all the vines were affected in a vineyard of which, except for the plants growing next to a road. These were sprayed according to information from the winemaker with a mixture of vitriol and lime to deter by their unappetizing appearance and the unpleasant taste of the walkers from stealing the grapes. Millardet then presented further experiments (mainly in the Rebgärten of Château Dauzac ). Published in 1885 and several writings in which he recommended the Bordeaux mixture as an appropriate means to combat downy mildew In the French language the method Millardet - David procedure was named after Ernest David, Technical Director of Château Dauzac.

Operation

The Bordeaux mixture containing Cu2 ions, which act in the fungal spores as enzyme poisons and prevent their germination. It has a protective effect, so it must be applied preventively.

Toxicity and ecotoxicity

Bordeaux mixture is strongly alkaline due to the contained quicklime and in particular may result in undiluted form to skin burns. In case of overdose, the treated plants are damaged.

For the consumer, provide any residue of Bordeaux mixture on fruits and vegetables is no risk you are not represent in these quantities harmful to human health and can be easily washed off.

If Bordeaux mixture, as usual in the wine, used for a long time, there is an accumulation of copper in the soil. Then earthworms are very sensitive. The leaching into ground and surface water plays only a minor role. Improper use will lead to increased coulure the vines.

Areas of application and registration situation

Bordeaux mixture is used for the control of downy mildew in grapevines. Their second important field was formerly the control of late blight (Phytophthora infestans ) of potato. In addition, it acts as a repellent to some insects and has ovicidal effect, so it can kill insect eggs.

Today in Switzerland, several preparations are approved, corresponding in composition of the Bordeaux mixture. You can also be used in the wine against downy mildew and gray mold (Botrytis cinerea), in vegetable cultivation, among others against Septoria leaf spot on tomatoes and celery, in Berries and in fruit scab and bacterial canker of cherry.

In Germany and Austria the Bordeaux mixture is no longer authorized as pesticides. There, however, comparable copper-containing preparations with a similar field of application are available.