Chapter VIII 



Enemies 



)HE iris formerly was regarded as im- 

 mune from disease and from insect attacks, 

 but, like many other plants after they be- 

 come subjects of cultivation, during recent years it 

 has become somewhat more liable to them — mainly 

 as the result of improper treatment or of environment. 

 It is still, however, unusually free from serious troubles. 



DISEASES. — There are several diseases caused by 

 vegetable parasites, which are not common. Rot is 

 the most serious disease. It has been a subject of 

 considerable study by a number of noted Plant Pathol- 

 ogists* and they have discovered the cause of it, 

 and have ascertained some of the conditions most 

 favorable for its development. This rot is caused by 

 the Bacillus carotovorus, which is supposed to be the 

 same bacterium that produces the soft rot in many 

 corhmon vegetables and other plants. Ordinarily it 

 enters through the tender growing tissues of the rhi- 

 zome at the base of the leaves or through wounds in 

 the body of it. Usually when an Iris plant becomes 



*Including the following who courteously have furnished information as to 

 their conclusions from their investigations: 

 Dr. H. H. Whetzel, Professor at Cornell Universitv. 

 Dr. L. M. Massey, Assistant Professor at Cornell University. 

 Dr. E. P. Clinton, Botanist at Conn. Agricultural Experiment Station. 

 Professor E. M. R. Lamkey, Floricultural Pathologist at University of Illinois. 



