CHAPTER XL 



DISEASES OF TREES AND VINES 



A few suggestions concerning pathological conditions which 

 arise in trees and vines and prescription of treatment and remedies 

 may be helpful : First, diseases demonstrated to be caused by fungi 

 and bacteria; second, abnormal conditions, of which the causes are 

 not yet clear. 



Effect of mildew on young growth of grape vine. 



Powdery Mildews. Fungi which bring upon the leaf surface the 

 appearance of a whitish powder and afterwards cause the leaf to 

 curl and dry without producing marked swelling, perforation or dis- 

 coloration, can be checked by the use of sulphur. The chief of these 

 is the mildew of the grape, the mildew of the apple, appearing chiefly 

 on the young growth, etc. The way to use sulphur for these fungi 

 is to throw finely ground or sublimed sulphur on the young foliage 



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