This section is from the book "The Standard Cyclopedia Of Horticulture Vol2", by L. H. Bailey. See also: Western Garden Book: More than 8,000 Plants - The Right Plants for Your Climate - Tips from Western Garden Experts.
A bluish green copper compound that settles out when freshly slaked lime and a solution of copper sulfate (blue-stone) are mixed. Many formulas have been recommended and used. The 5-5-50 formula may be regarded as standard. In such a formula the first figure refers to the number of pounds of copper sulfate, the second to the stone or hydrated lime, and the third to the number of gallons of water. Bordeaux must often be used as weak as 2-2-50, on account of injury to some plants.
To make fifty gallons of bordeaux mixture, proceed as follows:
(1) Pulverize five pounds of copper sulfate (blue vitriol), place in a glass, wooden, or brass vessel, and add two or three gallons of hot water. In another vessel slake five pounds of quicklime in a small amount of water. When the copper sulfate is all dissolved, pour into a barrel and add water to make forty or forty-five gallons. Now strain the lime into this, using a sieve fifty meshes to the inch or a piece of cheese-cloth supported by ordinary screening. Stir thoroughly, and add water to the fifty-gallon mark. The flocculent substance which settles is the effective fungicide. Always stir vigorously before filling the sprayer. Never add the strong lime to strong vitriol. Always add a large amount of water to one or the other first. Blue vitriol used alone would not only wash off quickly in a rain, but cause a severe burning of fruit and foliage. Lime is added to neutralize this burning effect of the copper. If the lime were absolutely pure, only slightly more than one pound would be required to neutralize this burning effect.
For many purposes an excess of lime is not objectionable and may be desirable.
Fig. 1291. Tip-burn of potato leaf. - A physiological difficulty or disease, due to some so-called "constitutional" disorder or obstruction (Vermont Experiment Station).
For nearly ripe fruit and ornamentals an excess of lime augments spotting. In such cases the least amount of lime possible should be used. Determine this by applying the cyanide test (2).
(2) Secure from the druggist 10 cents' worth of potassium ferrocyanide (yellow prussiate of potash) and dissolve it in water in an eight-ounce bottle. Cut a V-shaped slit in one side of the cork, so that a few drops of the liquid can be obtained. Now proceed as before. Add lime with constant stirring until a drop of the ferrocyanide ceases to give a reddish-brown color.
(3) When bordeaux mixture is desired in large quantities, stock solutions should be made. Place one hundred pounds of copper sulfate in a bag of coffee-sacking, and suspend in the top of a fifty-gallon barrel, and add water to the fifty-gallon mark. In twelve to fifteen hours the vitriol will be dissolved and each gallon of solution will contain two pounds of copper sulfate. Slake a barrel of lime, and store in a tight barrel, keeping it covered with water. Lime so treated will keep all summer. It is really hydrated lime. This is often dried, pulverized, and offered on the market in paper bags of forty pounds each, under such names as ground lime, prepared lime, hydrated lime, and the like. If the paper is not broken, the lime does not air-slake for a long time. One and one-third pounds of hydrated lime equals in value one pound of quicklime. Air-slaked lime cannot be used in preparing bordeaux mixture.
Arsenical poisons can be combined with bordeaux mixture.
For use on nearly mature fruit and on ornamentals. Does not discolor. Weigh out three ounces of copper carbonate, and make a thick paste with water in a wooden pail. Measure five pints of strong ammonia (26° Baume) and dilute with three or four parts of water. Add ammonia to the paste, and stir. This makes a deep blue solution. Add water to make fifty gallons.
For use in the above formula, it may be secured as a green powder, or may be prepared as follows: Dissolve twelve pounds of copper sulfate in twelve gallons of water in a barrel. Dissolve fifteen pounds of sal-soda in fifteen gallons of water (preferably hot). Allow the solution to cool; then add the sal-soda solution to the copper-sulfate solution, pouring slowly in order to prevent the mixture from working up and running over. A fine precipitate is formed which will settle to the bottom if allowed to stand over night. Siphon off the clear liquid. Wash the precipitate by adding clear water, stirring, and allowing to settle. Siphon off the clear water, strain the precipitate through muslin, and allow it to dry. This is copper carbonate. The above amounts will make about six pounds.
See Sulfate of copper.
Used for disinfecting pruned stubs and cleaned-out cankers, at the rate of one part in 1,000 parts of water. Can be secured from the druggist in tablet form in vials of twenty-five each, and costing 25 cents. One tablet makes a pint of solution. Make and store solution in glass and label "poison."
A pungent, clear liquid, very irritating to eyes and nose. Obtained at any drugstore at about 40 cents a pint. Used for potato-scab, oat smut, bunt in wheat, soil disinfection, and so on.
Offered for sale in the following forms: (a) Ground rock or ground limestone; air-slaked lime is of the same composition, i.e. a carbonate of calcium. (b) Lump, barrel, stone, or quicklime; this is burned limestone, and should test at least 90 per cent oxid of calcium, (c) Prepared, ground, or hydrated lime; this is water- or steam-slaked quicklime, dried and pulverized. Used as an applicant to the soil to correct acidity, for club-root of cabbage, and for preparing spray mixtures.
In the many possible combinations, lime-sulfur is coming to be equally as important as bordeaux mixture, in the control of many plant diseases.
(1) Flowers of sulfur or very finely powdered sulfur is often dusted on plants for surface mildews.
(2) A paste o'f equal parts of lime, sulfur, and water. This is painted on the heating-pipes in the greenhouse, and is valuable for keeping off surface mildews.
(3) Home-boiled dilute lime-sulfur. This solution has been widely used in the past as a dormant spray, particularly for San Jose' scale and peach leaf-curl. It is likely to be supplanted by (4) or (5). For preparation see page 1043.
(4) Home-boiled concentrated lime-sulfur - When a great deal of spraying is to be done, a concentrated lime - sulfur solution may be boiled at home and stored in barrels to be used as needed. For method of preparation see page 1043.
Fig. 1292. Perithecium of apple scab, showing spores.
Test with a Baume hydrometer, which has a scale reading from 25° to 35°. Dilutions are reckoned from a standard solution testing 32°. If the solution tests only 28°, it is not so strong as standard, and cannot be diluted so much as a solution testing 32°. The table shows the proper dilution for solutions testing 25° to 35° Baume:
Decimals are given in all cases, but for practical purposes the nearest even gallon or half gallon can be used, unless appliances for more accurate measurement are at hand. It is understood in making all dilutions that water is added to one gallon of the concentrate to make the stated amount. Do not measure out the stated amount of water and add the concentrated solution to it.
(5) Commercial concentrated lime-sulfur - As manufactured and placed on the market is a clear amber liquid, and should test 32° to 35° Baume. It costs about 20 cents a gallon retail, and comes ready to pour into the spray tank. For apple and pear diseases. Arsenate of lead can be used with this solution, and increases its fungicidal value.
(6) Scott's self-boiled lime-sulfur - This is a mechanical mixture of the two substances, and is really not boiled, the heat being supplied by the slaking lime. In a small barrel or keg place eight pounds of good quicklime. Add water from time to time in just sufficient amounts to prevent burning. As soon as the lime begins to slake well, add slowly (preferably through a sieve) eight pounds of sulfur flour. Stir constantly, and add water as needed. As soon as all bubbling has ceased, check further action by adding a quantity of cold water, or pour into a barrel or tank and make up to fifty gallons. Keep well agitated. Very effective against peach scab and brown rot. Several other formulas have been used: 10-10-50 and 5-5-50. Arsenate of lead can be used with this mixture.
By using boiling water and allowing the hot mixture to stand for half an hour, a stronger spray mixture than the above can be secured. It cannot be used safely on peaches, but has been used successfully on grapes for surface mildew. The addition of sulfate of iron or sulfate of copper, one or two pounds to fifty gallons, has been used for apple rust.