DISEASES OF GINSENG. 79 



CHAPTER XXII. 

 DISEASES OF GINSENG. 



Root Rots Of Ginseng, 

 (by prof. w. h. rankin.) 



During the progress of the work on the diseases of ginseng, 

 much information has accumulated concerning the different root 

 rots. These diseases are probably of more importance to the 

 grower than he would ordinarily suspect. An attack of Alterna- 

 ria blight stops the growth for the season and stunts the plant, the 

 root, however, is intact and growth proceeds the next year. So 

 it is with the other leaf diseases. But a disease affecting the root 

 either destroys it immediately or injures it to the extent that it is 

 unmarketable. The loss of a few roots each year means considera- 

 ble when totaled. JThe root rots are due mostly to certain common 

 soil fungi and bacteria, which grow abundantly and become para- 

 sitic under certain soil conditions. For example, the fungus 

 causing the fiber rot or end rot is present in almost all cultivated 

 soils, but it only becomes a parasite on root crops when the soil is 

 heavily limed or in some other way made alkaline. A knowledge 

 of this fact makes it possible to protect the plants from this fungus 

 by using fertilizers that will make the soil acid instead of alkaline. 

 The soft rot develops only in heavy, soggy soil, therefore the par- 

 asite causing the disease is rendered harmless by thorough soil 

 drainage. Such methods of control are called "soil treatments." 



The first essential in working with a root disease is to un- 

 derstand the organism and the conditions under which it becomes 

 a parasite. This discovered, a soil treatment is generally available 



