EXPERIMENT STATION BULLETINS. 323 



sel dissolve the carbonate of soda (sal-soda), pour together and mix 

 thoroughly; when all action has ceased, add the ammonia water, and before 

 using dilute with the remainder of the water. 



AMMONIA SOLUTION OF COPPER CARBONATE. 



Copper carbonate can be obtained as a dry powder, and is prepared for 

 use as a fungicide, as follows: Dissolve 3 ozs. of copper carbonate in one 

 quart of ammonia water (26°), and dilute to 32 gallons. If copper car- 

 bonate can not be readily obtained, the formula given as modified eau 

 celeste can be used instead, and will be found considerably cheaper. A 

 commercial ammoniacal carbonate of copper is known as liquid copperdine. 

 A mixture that will be practically the same, on solution, can be made by 

 mixing one half pound of powdered copper sulphate and one pound of 

 carbonate of ammonia. This can also be purchased pulverized and mixed, 

 ready for use by merely adding 32 gallons of water. 



The commercial name of this mixture is dry copperdine. 



Of the various copper mixtures, none have proven more satisfactory 

 than the above, which was first recommended by Prof. S. W. Johnson, 

 director of the Connecticut experiment station.* It is also cheaper 

 than any except the Bordeaux mixture, and although the latter is fully as 

 effectual as a remedy, is not likely to clog the pump or nozzle, or to spot 

 the clothing of the operator, and disfigure the fruit, which is so serious a 

 fault in that remedy. 



Commercial carbonate of copper suspended in water has been tried, but 

 is hardly satisfactory; however, if the precipitate formed in making 

 modified eau celeste is used without being dissolved in ammonia, it will be 

 found quite satisfactory, if applied at once. 



POTASSIUM SULPHIDE. 



For some diseases, such as the gooseberry and other powdery mildews, a 

 solution of sulphide or sulphuret of potassium (commonly known as 

 " liver of sulphur " ) is an excellent remedy. The usual formula is one 

 ounce to three gallons, and for diseases of the above class it is a cheap and 

 effective remedy, and is particularly desirable in case pf the gooseberry 

 mildew, as it does not discolor the fruit, as would the copper compounds. 



DISEASES OP THE GRAPE. 



Few, if any, of our cultivated plants are attacked by more fungous 

 diseases, or are more injured by them, than is the grape. It seems as if, 

 whatever be the nature of the season, there is some destructive grape dis- 

 ease for whose development it is especially adapted. 



Probably the best known and, in the past, the most destructive diseases of 

 the grape are the mildews. These are of two kinds, and are commonly 

 known as the downy and the powdery forms. 



The downy mildew (Fig. 1.) works in the interior of the leaves, and 

 gives the upper side a yellowish appearance; in a short time the spores 

 are produced on the 'extremity of minute threadlike stems, that protrude 

 through the stomata on the under side of the leaves, and look like downy 

 or frosty patches. The spores soon drop off, and, if they fall on a moist 



* Connecticut Experiment Station Report, 1890. 



