CHAPTER XXXVII. 
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. 
Powdery Mildews.—Fungi which bring upon the leaf sur- 
face the appearance of a whitish powder and afterwards cause 
the leaf to curl and dry without producing marked swelling, 
perforation or discoloration, can be checked by the use of sul- 
phur. ‘he 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 described in Chapter XXV. 
Apple and Pear Scab on Fruit, Wood and Foliage. 
Leaf-Spotting, Puncturing or Deforming Fungi—These 
classes are usually distinguishable by the results they produce. 
The mildew of the peach produces dense, whitish patches on the 
leaves and growing fruit; the curl-leaf fungus of the peach pro- 
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