372 



The Spraying of Plants. 



family, and they are beautifully and delicately marked. They 

 fly mostly in the evening. The ground color is a soft gray, but 

 there are various markings of a darker color, some red or 

 reddish-brown parts being present. 



Treatment. Hand picking is the most common method of 

 destroying the larvae, but any of the poisons in use against 

 chewing insects would answer the purpose as well. 



TURNIP. 



INSECT ENEMIES. 



Maggot. See under CABBAGE. 



FUNGOUS DISEASES. 



VEKBENA. 



Mildew ; Rust (Erysiphe Cichoracearum, DC., or Oidium ery- 

 siphoides, Fr.). See under CUCUMBER. 



FUNGOUS DISEASES. 



VIOLET. 



Mildew. See under PANSY. 



Rust ; Spot ; Violet Disease 

 (Cercospora Violce, Sacc.). All 

 violet growers are familiar 

 with this disease (Fig. 92), 

 which causes the formation 

 upon violet foliage of small, 

 circular, grayish -white spots 

 having a dark center. The 

 first appearance of the disease 

 may occur during summer, 

 while the plants are in the 

 open ground. Or it may not 

 be visible until late in win- 

 ter. Surrounding conditions 

 appear to have a strong influ- 

 ence in the development of the 

 fungus. Too much heat, care- 

 lessness in watering, fresh stable manure, and improper ven- 

 tilation have all been advanced as immediate causes of the 



FIG. 92. Violet disease. 



