Fungicides 447 



ness of distribution effected. From 1.25 to 2.5 pounds are ap- 

 plied per tree in each application. '* In localities where apple 

 scab is less abundant than in the lake counties, as seems to be 

 the case in most of the Hudson River section, the quantity of 

 sulfur applied per tree may be reduced. It would be well, 

 however, to regard these as minimum amounts until expe- 

 rience has shown that they can be reduced with safety." 



Dusting appears to be slightly more expensive than spray- 

 ing. The cost of materials is higher, but this factor in the 

 total cost is partially overcome by the lower cost of applica- 

 tion. The chief advantage in dusting, however, lies in the 

 extreme rapidity with which the dust can be applied. This 

 appears to permit the application of the fungicide at periods 

 when the weather conditions favor infection with apple scab, 

 and to result in comparative flexibility in the spray schedule. 



Ammoniacal solution of copper carbonate. — This solution 

 contains no sediment, and on drying leaves no unsightly 

 marks. It may therefore be used when the spotting that 

 the Bordeaux mixture causes precludes the use of that 

 fungicide. The mixture consists of a solution made by dis- 

 solving copper carbonate in ammonia-water in the following 

 proportions : 



Copper carbonate 6 ounces 



Ammonia, about 3 pints 



Water 50 gallons 



Weigh out the proper amount of copper carbonate. Set a 

 very small portion of this aside, and dissolve the remainder 

 of it in diluted ammonia, using only enough ammonia to 

 dissolve it. Then add the portion of copper carbonate which 

 was reserved. This will insure the use of no more ammonia 

 than is necessary. It is better to have a little too much of 

 the carbonate in the solution than to have too much ammonia. 

 The strong solution made in this way can be diluted with the 

 proper amount of water. The copper carbonate may be 

 purchased directly from the drug-store, or it may be prepared 

 at home. 



