DISEASES OF GINSENG. 95 



in the soils of most ginseng gardens. When conditions (of which 

 all?:alinity seems to be most important) become especially favorable 

 it quickly shows its parasitic habit. 



Effect of the Disease on the Plant. — If a ginseng plant 

 suffering from the fiber rot be dug up and the soil carefully re- 

 moved it may be observed that the tiny feeding roots fibers are at 

 first killed back to the larger root branches. Here new fibers sent 

 out densely covered with the water gathering root hairs. These 

 being exposed to the great number of spores produced on the 

 diseased fibers, soon are attacked and killed. Again new fibers 

 arise to succumb in turn to the attacks of the fungus, and so on 

 during the entire season. The water gathering organs being thus 

 repeatedly destroyed the plant soon begins to show the effects in 

 the loss of the natural deep green color of its leaves and their pre- 

 mature coloration. The drain on the plant to rebuild repeatedly 

 the destroyed feedling roots weakens the entire root structure. 

 The fungus now attacks the larger fibers and even the main root 

 itself, rotting off the lower portion (Fig. 41) or infesting the epi- 

 dermis and outer flesh of the root, causing "rust". With the 

 destruction of all the fibrous roots the water supply is finally cut 

 off and the tops wilt. In wet weather, diseased plants may show 

 a little premature coloration and may go through the season and 

 mature seed. If they do succumb they wilt suddenly with the 

 final rotting away of the last fiber. In dry seasons not only are 

 the fibers less easily rebuilt but they are at the same time less 

 efficient. To supply the large leaf surface with its required 

 amount of water from a very dry soil calls for a full quota of ab- 

 sorbing rootlets in prime condition. The cutting off of these by 

 the rot results in starvation of the top, its loss of color, premature 

 coloi'ation and final death. Diseased plants which pull through 

 the first season, start the second season under a great handicap. 



