Violet Diseases 357 



ing as an irregular discoloration which extends in- 

 wards. Affected foliage rots and becomes unsightly. 

 The acervuli are thin and few in numbers; the co- 

 nidia are yellowish. 



Phyllosticta Leaf Spot 



Caused by Phyllosticta viola Desm. 



Symptoms. This disease is characterized by nu- 

 merous circular whitish spots, averaging about an 

 eighth of an inch in diameter. Often the spots run 

 together and involve the entire leaf (fig. 74, a.). 

 The pycnidia are found on the dead tissue of the 

 spots. The disease is commonly found on out-of- 

 doors violets, but it is also met with under green- 

 house conditions. The same disease also attacks the 

 pansy. 



Organism. The pycnidia of the fungus are 

 brown, minute, and numerous. The spores are mi- 

 nute and subcylindrical. 



Control. It is probable that spraying with a stan- 

 dard fungicide will control the disease. All infect- 

 ed material should be destroyed by fire. 



AscocHYTA Leaf Spot 



Caused by Ascochyta viola Sacc. 



This disease is characterized by scorched appear- 

 ing patches on the leaves. The affected plants soon 

 become unsightly while the blossoms produced are 

 stunted and valueless commercially. Little is known 



