Coleus Diseases 245 



black mass of spores which are hyaline when looked 

 at individually. 



Coleus 



Cultural Considerations same as Geranium, p. 

 260. 



Diseases of the Coleus 



Coleus is an imusual hardy plant in the sense that 

 it is subject to so few diseases. 



Damping Off 



Caused by Rhizoctonia solani Kuhn. 



It seems that the variegated green varieties are 

 more susceptible to damping ofF than the variegated 

 red and yellow. Infected cuttings show lesions at 

 the stem and above the surface of the soil. As the 

 lesions spread and work in deeper in the tissue, the 

 cutting topples over. For a description of the causal 

 organism and methods of control, see p. 20. 



Broom Rape 



Caused by Orobanche ramosa L. 



Coleus is often subject to the attacks of a broom 

 rape (fig. 51). The trouble was found by Hal- 

 sted and Kelsey * on greenhouse plants. Orobanche, 

 the broom rape genus, is of interest to greenhouse 

 growers, because of its parasitic nature. Broom rape 



* Halsted, B. D., and Kelsey, J. A., Nevr Jersey Agr. Expt. Sta., 

 23rd Ann. Kept.: 408, 1902. 



