1904.] 



Potato Disease. 



287 



10 lb. for the 12 lb. of copper, slake it, and mix with hot water, 

 then run in 10 lb. of agricultural treacle (any cheap sugar will 

 do if only small lots are being made), stir up well, heating, if 

 possible, until the lime and treacle have combined, then pour 

 the mixture into the copper sulphate solution as before. This 

 time a green solution of copper saccharate will be obtained, but 

 by the action of the air it will precipitate copper carbonate, 

 which will not be washed off by rain at all readily. This 

 mixture is very effective, but must be used very soon after 

 making up. 



Bordeaux mixture with soda instead of lime may be made 

 as follows : — 



Copper sulphate or bluestone 12 lb. 



Washing soda or soda crystals 15 lb. 



Water 100 gals. 



Follow the instructions given above, using the solution of 

 washing soda instead of the lime and water. 



Another mixture which may be used is " Cupram " : — 



Copper carbonate ... ... ... ... ... 10 oz. 



Ammonia {Liquor Ammonia fortiss. 080) 5 pints. 



Water ... ... ... ... ... ... ... 1 00 gals. 



Add the ammonia to four or five gallons of water, and throw 

 in the copper carbonate little by little, stirring vigorously until 

 dissolved. Then dilute with the rest of the water. A clear 

 blue solution results, which is advantageous in never clogging 

 the nozzles of the sprayer. This mixture can be made up and 

 kept in the concentrated form until required for use. It is 

 particularly suited to fruit trees and work under glass. 



The strength of any of the above mixtures can be varied ;. 

 up to 20 lb. of copper sulphate, with a proportional amount of 

 lime, may be used for 100 gallons of water, but a mixture of 

 this strength should only be used on mature plants with fully- 

 developed leaves. 



Sulphate of copper compositions are poisonous, and the tubs„ 

 pails, or other vessels which have contained Bordeaux mixture,, 

 or in which it has been made, must, therefore, not be used for 

 farm animals. 



Dry powders containing the copper and lime products are 

 sometimes dusted on to the leaves, but it is more difficult to 

 secure adhesion, and the method is more wasteful of copper. 



