214 Diseases of Greenhouse Crops 



likely that this disease will become troublesome in 

 greenhouses where begonia is grown on a large scale. 



Root Rot 



Caused by Rhizoctonia solani Kuhn. 



The symptoms of root rot on begonia are the 

 same as those described for alternanthera. The fun- 

 gus also causes a damping off disease on young be- 

 gonia cuttings. 



Root Knot (fig. 43), see Nematode, p. 28. 



Caladium {Caladium sp,) 



Cultural Considerations. Caladiums should never 

 be allowed to become pot bound. They require a 

 medium temperature, plenty of water, ventilation, 

 and drainage. As the growing season is over and 

 the plants lose their leaves, the pots should be laid 

 on their sides and the water withheld sufficiently 

 to prevent growth. 



Diseases of the Caladium 



Caladiums, it seems, are very hardy. The fungi 

 recorded on matured parts of this plant may be men- 

 tioned : 



Cercospora caladii Cke., Macrophoma surinamen' 

 sis (B. and C.) Berl. and Vogl., Monilia prunosa 

 Cke. and Mass.; Sphd^rella caladii (Schw.) Sacc, 

 Uromyces caladii (Schew.) Farl. 



