PROTECTING PLANTS 197 



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 to- 

 gether. This is not necessary, and is often impracticable for commer- 

 cial work. It is preferable to dilute the copper sulfate solution. Never 

 pour together the strong stock mixtures and dilute afterward. Bor- 

 deaux 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 mix- 

 ture, 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 hun- 

 dred gallons of the mixture. This mixture will prevent the bordeaux 

 from being washed off by the heaviest rains. 



Ammoniacal copper carbonate. — Copper carbonate, 5 oz. ; ammo- 

 nia, 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 



