The standard fungicide is bordeaux mixture, made in several forms. The second most important fungicide for the home gardener is ammoniacal copper carbonate. Sulfur dust (flowers of sulfur) and liver of sulfur (potassium sulfide) are also useful in dry or wet sprays for surface mildews. The lime-sulfur wash, primarily an insecticide, also has fungicidal property (p. 195).

Bordeaux Mixture

Copper sulfate, 4 lb.; stone lime or quicklime (unslaked), 4 lb.; water, 50 gal. This formula is the strength usually recommended. Stock mixtures of copper sulfate and lime are desirable. They are prepared in the following way: -

(1) Dissolve the required amount of copper sulfate in water in the proportion of one pound to one gallon several hours before the solution is needed, the copper sulfate crystals being suspended in a sack near the top of the water. A solution of copper sulfate is heavier than water. As soon then, as the crystals begin to dissolve the solution will sink, keeping water in contact with the crystals. In this way, the crystals will dissolve much sooner than if placed in the bottom of the barrel of water. In case large quantities of stock solution are needed, two pounds of copper sulfate may be dissolved in one gallon of water.

(2) Slake the required amount of lime in a tub or trough. Add the water slowly at first, so that the lime crumbles into a fine powder. If small quantities of lime are used, hot water is preferred. When completely slaked, or entirely powdered, add more water. When the lime has slaked sufficiently, add water to bring it to a thick milk, or to a certain number of gallons. The amount required for each tank of spray mixture can be secured approximately from this stock mixture, which should not be allowed to dry out.

(3) Use five gallons of stock solution of copper sulfate for every fifty gallons of bordeaux required. Pour this into the tank. Add water until the tank is about two-thirds full. From the stock lime mixture take the required amount. Knowing the number of pounds of lime in the stock mixture and the volume of that mixture, one can take out approximately the number of pounds required. Dilute this a little by adding water, and strain into the tank. Stir the mixture and add water to make the required amount. Experiment stations often recommend the diluting of both the copper sulfate solution and the lime mixture to one-half the required amount before pouring together. This is not necessary, and is often impracticable for commercial work. It is preferable to dilute the copper sulfate solution. Never pour together the strong stock mixtures and dilute afterward. Bordeaux mixture of other strengths, as recommended, is made in the same way, except that the amounts of copper sulfate and lime are varied.

(4) It is not necessary to weigh the lime in making bordeaux mixture, for a simple test can be used to determine when enough of a stock lime mixture has been added. Dissolve an ounce of yellow prussiate of potash in a pint of water and label it " poison." Cut a V-shaped slit in one side of the cork so that the liquid may be poured out in drops. Add the lime mixture to the diluted copper sulfate solution until the ferro-cyanide (or prussiate) test solution will not turn brown when dropped from the bottle into the mixture. It is always best to add a considerable excess of lime.

"Sticker " Or Adhesive For Bordeaux Mixture

Resin, 2 lb.; sal soda (crystals), 1 lb.; water, 1 gal. Boil until of a clear brown color - one to one and one-half hours. Cook in iron kettle in the open. Add this amount to each fifty gallons of bordeaux for onions and cabbage. For other plants difficult to wet, add this amount to every one hundred gallons of the mixture. This mixture will prevent the bordeaux from being washed off by the heaviest rains.

Ammnoniacal Copper Carbonate

Copper carbonate, 5 oz.; ammonia, 3 pt.; water, 50 gal. Dilute the ammonia in seven or eight parts of water. Make a paste of the copper carbonate with a little water. Add the paste to the diluted ammonia, and stir until dissolved. Add enough water to make fifty gallons. This mixture loses strength on standing, and therefore should be made as required. It is used in place of bordeaux when one wishes to avoid the coloring of maturing fruits or ornamental plants. Not as effective as bordeaux.

Potassium Sulfide

Potassium sulfide (liver of sulfur), 3 oz.; water, 10 gal. As this mixture loses strength on standing, it should be made just before using. It is particularly valuable for the powdery mildew of many plants, especially gooseberry, carnation rust, rose mildew, etc.

Sulfur

Sulfur has been found to possess considerable value as a fungicide. The flowers of sulfur may be sprinkled over the plants, particularly when they are wet. It is most effective in hot, dry weather. In rose houses it is mixed with half its bulk of lime, and made into a paste with water. This is painted on the steam pipes. The fumes destroy mildew on the roses. Mixed with lime, it has proved effective in the control of onion smut when drilled into the rows with the seed. Sulfur is not effective against black-rot of grapes.