DISEASES 153 



Spraying is not a curative measure, for the 

 reason given above, that the growing portion of 

 the fungus is in the tissues of the leaf, and cannot 

 be reached by the fungicide. What spraying will 

 do, if applied in time, is to prevent the first infec- 

 tion of leaves, by covering the surface with a sub- 

 stance poisonous to the germinating spores. 



To accomplish this object the disease should be 

 anticipated; in other words, spraying should 

 commence before the disease appears. An ex- 

 perienced planter will know at what particular 

 season of the year infection is most likely to occur. 

 When a disease is present spraying will arrest its 

 progress, by destroying the spores that alight on 

 the surface of the foliage. 



Bordeaux mixture is, perhaps, the best for 

 spraying, and it can now be procured in the dry 

 condition, ready for dissolving in water when re- 

 quired. As a rule, spraying is continued for too 

 long a time. The moment the solution commences 

 to drip from the foliage it is time to stop. Always 

 commence with a solution containing more water 

 than is prescribed in the directions given, and 

 gradually decrease the amount of water until the 

 leaves show injury. As some plants will bear a 



