VINE DISEASES, 153 



developed at the bottom of tlie row or chain. The mildew 

 develops ou the upper surface of the leaves, young shootis, 

 and fruit. 



During the autumn thesiinimsr form of fruit ceases to 

 be produced, and in its place minute balls, at first 

 yellowish, and afterwards blackish brown, appear in con- 

 siderable numbers on the mycelium still present on the 



[Photo: H. A. Smith. 

 BUNCH OF GRAPB3 INFECTED WITH MILDEW. 



leaves, shoots, and fruit. These minute balls, smaller 

 than the head of a small pin, represent the winter form of 

 fruit, containing spores in their interior. Examined 

 under a microscope, these winter fruits are very beautiful, 

 being provided with a circle of delicate spreading spines, 

 each of which is more or less curled at the tip. These 

 winter fruits remain unchanged until the following spring. 



