(c) Slake 2 pounds of good, fresh quicklime and add water to make 2 gallons of milk of lime. Add 1 pound of white arsenic and boil hard for forty min utes. Add water to bring the resulting compound up to 2 gallons. Use I or 2 quarts of this stock solu tion to 50 gal lons of water or Bordeaux.
London Pur ple. — This is used in the same propor tion as Paris green, hut as it is more caustic it should be ap plied with two or three times its weight of lime, or with t h e Bordeaux mixture. T h e composition of London purple is variable, and unless good reasons e x is t for supposing that it contains as much arse nic as Paris green, use the latter poison. Do not use London purple on peach or plum trees unless considerable lime is added. Once much used.
Hellebore.— Fresh white hellebore, 1 ounce ; water, 3 gallons.
Apply when thoroughly mixed. This poison is not so energetic as the arsenites, and may be used a short time before the sprayed parts mature. For insects which chew. Much used for currant-worms.
Fungicides.
The Bordeaux mixture, with variations in the propor tion of water to suit the particular kind of plant and grade of development of the crop and of the disease, has become practically the universally used medium for spraying purposes. The standard formula is as follows : Copper sulfate, 3 to 6 pounds ; quicklime, 4 pounds ; water to make 50 gallons.
This solution is often used successfully at half strength on delicate foliage. The solution of copper sulfate is some times used without the lime on diseases of woody parts, such as apple canker and anthracnose of raspberry canes. In case of such use, the spraying must be done at a time before the foliation begins.
The Bordeaux mixture may be combined with Paris green and other arsenites, as explained under those heads on the preceding page, and thus destroy both insects and fungous diseases at the some time that the caustic or injurious effect of the arsenic is lessened.
There are many proportions in which the ingredients are combined to make Bordeaux mixture. The 6-4-50 for mula is not now often used, as the amount of copper sulfate (or blue-stone) is greater than need be. The 3-4-50 formula is now much used.
Make stock solutions by dissolving 1 lb. sulfate to I gal. water in a barrel ; and by dry-slaking the lime and then adding water till one gallon holds 1 lb. lime. Dilute these stock solutions before they are put together.
There must be lime enough to kill the caustic action of the copper sulfate, This may be tested by dropping a solution of ferrocyanide of potassium on the surface of the Bordeaux mixture: if the drops turn brown or red, more lime should be added.
Ammoniacal Carbonate of Copper.—Copper carbonate, 5 ounces ; ammonia (26° Beaum6), 3 pints ; water, 45 gallons.
Make a paste of the copper carbonate with a little water. Dilute the ammonia with 7 or 8 volumes of water. Add the paste to the diluted ammonia and stir until dissolved. Add enough water to make 45 gal lons. Allow it to settle and use only the clear blue liquid This mixture loses strength on standing. For fungouL diseases.
Copper Sulfate Solution.—Copper sulfate, 1 pound ; water, 15 to 25 gallons.
Dissolve the copper sulfate in the water. This should never be applied to foliage, but must he used before the buds break. For peaches and nectarines, use 25 gallons of water. For fungous diseases, but now largely supplanted by the Bordeaux mixture. A much weaker solution is recommended for trees in leaf.
Potassium Sulfid Solution.—Potassium sulfid (liver of sulfur), to 1 ounce ; water, 1 gallon.
This preparation loses its strength on standing, and should therefore be made immediately before using. Particularly valuable for surface mildews.
Maxwell Dust-Spray.— Fresh lime, 1 barrel ; copper sulfate, 25 pounds ; concentrated lye, 5 pounds ; powdered sulfur, 25 pounds ; Paris green, 6 pounds.
Spread lime in a large, shallow box, breaking into as small lumps as possible. Dissolve the copper sulfate in six gallons boiling water ; also dissolve the lye in five gallons hot water. Keep separate. Sprinkle copper sulfate solution over the lime. Follow with lye water. If the lime does not all crumble to a dust, use clear water to finish. Screen the lime through a fine sieve, rub the sulfur through the sieve into the lime, add the Paris green and thoroughly mix both with lime. Lime should crumble to powder, not granules.
Copper sulfate water must be used hot, or the copper will recrystallize. Mixing should be done out-of-doors or in a separate building, as lime in slaking becomes very hot.
Missouri Experiment Station dust-spray. (To make 70 pounds of stock powder): —Copper sulfate, 4 pounds; quicklime, 4 pounds ; water in which to dissolve copper sulfate, 2i gallons ; water in which to slake quicklime, 27i gallons ; air-slaked lime thoroughly sifted, 60 pounds.
Dissolve the copper sulfate and slake quicklime separately, each in 2h gallons water. Pour at same time milk of lime and copper solution into a third vessel and stir thoroughly. Surplus water is then strained out and remaining wet material is thoroughly mixed with the 60 pounds of air-slaked lime. All lumps must be sifted out and the mixture must be perfectly dry. One pound each of sulfur and Paris green may be added.
The dust-sprays are useful where water is scarce or land is too rough or steep for the regular spraying machines.