How to make Bordeaux and Burgundy mixtures in small quantities.

Date:
[1950]
Catalogue details

Licence: Public Domain Mark

Credit: How to make Bordeaux and Burgundy mixtures in small quantities. Source: Wellcome Collection.

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    DIG FOR VICTORY LEAFLET No. 9 OW TO MAKE BORDEAUX AND BURGUNDY MIXTURES IN SMALL QUANTITIES H BORDEAUX MIXTURE he is the original and still the most effective fungicide for use against potato blight. It is also useful against leaf spot of celery, leaf curl of peaches and almonds, as well as against a number of other diseases affecting mainly the foliage of plants. Materials to use Bordeaux mixture is prepared from copper sulphate (bluestone), lime and water. The copper sulphate, which should be at least 98 per cent pure, is best bought in the form of powder or granular crystals, as these dissolve much more readily in water than the large blue crystals. Quicklime in lump form, fresh and free from impurities, was formerly the most common form of lime used, but nowa- days, ‘‘ hydrated lime ”’ is more con- venient ; as sold commercially it is free from grit and very pure. It should always be used quite fresh, for the material soon loses its strength in bags that have been opened and kept for some time. Both copper sulphate and hy- drated lime can be purchased in small amounts from shops supplying horti- cultural requisites. Preparing the mixture The ingredients for making 24 gallons of spray are : Copper sulphate 4 oz. Hydrated lime 3 0Z. Clean water. . 24 gal. A clean wooden, earthenware or (unchipped) enamelled bucket or other container to hold 24—3 gallons is best, for copper sulphate corrodes metal vessels, but a galvanized bucket may be used if it is well washed afterwards. Measure out 24 gallons of clean water into the container ; pour off about a quart into an earthenware or enamelled jug, and stir into this the 4 oz. of copper sulphate. While it is dissolving, put the 5 oz. of hydrated lime into the water remaining in the container and stir well to make a milky solution. When all the copper sulphate has dissolved, slowly pour the blue solution from the jug into the milk of lime in the bucket, stirring well all the time. The characteristic sky-blue colour of Bordeaux mixture will appear, and the spray is then ready for immediate use. Prepared in this way, the mixture should be quite safe for use on most plants. To make sure, the bright, clean blade of a penknife (not stainless steel) should be dipped into it for about a minute. If the blade becomes tarnished or darkened with a deposit of copper, more hydrated lime must be added. A more sensitive test is to dip a piece of blue litmus paper, obtainable from the chemist, into the mixture. It should remain blue ; if it turns pink, more lime must be added.
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