DISEASES OF THE VINE. ] 591 



exuded by aphides or by scale-insects, and is not directly 

 injurious to the plant. 



Irregular dull brownish spots are produced on the 

 surface of the leaf, of which the affected area soon dies, 

 and is followed by the formation of small whitish dots 

 which are the basidia of a fungus Gfoeospormm physalos- 

 forum-, Cav. The berries may become affected in the same 

 manner, but the disease never assumes a serious aspect. 

 Collctotrichum ampclinum* Cav. is a fungus which pro- 

 duces small irregular spots of a light olive green or 

 yellowish brown colour, on the under surface of the leaf. 

 This fungus is common on Vitis Labrvsca (the Isabella 

 grape), the leaves of which are often entirely covered by 

 these small spots, particularly if the plant shows signs of 

 chlorosis. 



Dark spots, often hardly distinguishable, are pro- 

 duced on the under surface of the leaf by the fungus 

 Ma cr emporium Vitis, Sorok., and small irregular or 

 roundish spots of an olive green colour which sooti become 

 brown and dry are due to Sphaerella Vitis, Fckl. These 

 fungi are checked by frequent dustings with sulphur. 



Gloeospotium cmpelophagum, Sacc. is the cause of 

 the so-called small-pox of the vine, or anthracnosis of the 

 leaf. The lesions consist in roundish spots or promi- 

 nences, which are at first brown and soon their central 

 part becomes grey or reddish. The disease is apt to 

 recur year after year, and as a preventive, all affected 

 leaves should be collected and burned. 



Cladosporium viticolum, Ces. and C7. Roesleri, Catt. 

 are two fungi which produce roundish or elongated brown- 

 ish spots along the nerves, invading both sides of the 

 leaf, and are more frequent on the lower leaves of the 

 shoots. Cercospira vituoia, Sacc. causes dry brown spots, 

 often quite large, on the upper surface of which are de- 

 veloped a number of minute black dots. Dendryphium 



