Begonia Diseases 213 



constricted slightly at the septum. The Conidio- 

 phores are short and cylindric. 



The Begonia (Begonia sp.) 



Cultural Considerations. Begonias have become 

 a very popular plant commercially. The tuberous 

 type is extensively grown imder glass. Throughout 

 the season, the plants require frequent applications 

 of liquid cow manure. They require an abundance 

 of light and air, but are very sensitive to draughts 

 and to exposure to direct sunlight. The best tem- 

 perature required is about 65 degrees F. In the 

 summer, the house should be frequently syringed in 

 order to keep it cool. 



Diseases of the Begonias 



Begonias, althou^ considered hardy plants, are 

 subject to a few important diseases. 



Powdery Mildew 



Caused by Oidium sp. 



Stewart* records a powdery mildew attacking the 

 stems but not the leaves of begonia. The trouble 

 appears as a white powdery fungus growth charac- 

 teristic of all similar mildews. Only the Oidiirai 

 or conidial stage of the fungus is present. It is not 



•Stewart, F. C, New York (Geneva) Agr. Expt. Sta. Bui. 388: 

 33». '9JO- 



