DISEASES OF GINSENG. 85 



when the rot begins at the crown, the water supply is shut off 

 quickly and tops wilt without the premature coloration. The 

 disease usually affects the cortical tissues just under the epidermis, 

 but often the entire root may suffer. 



The diseased portion will appear of a light brown color in 

 contrast with the white of the healthy parts. The epidermis does 

 not seem to be diseased and the brown discoloration appears be- 

 neath the skin. The boundary line between the diseased and 

 healthy tissue is in most cases definitely defined. In later stages 

 the root will be found to be entirely rotted, being soft and watery 

 and having a very strong, repugnant odor. The disease spreads 

 up and down the root by way of the sap tubes. 



The soft rotted roots when examined under the microscope 

 show an abundance of a fungus belonging to the genus Fusarium. 

 These are common soil fungi and are associated with many soft 

 rots of tuberous crops. Many kinds of bacteria are also found 

 abundant in the decaying tissues- Until more accurate observa- 

 tions and experiments can be made, it will be impossible to give 

 the exact cause of the disease. It is probable, however, that a 

 certain bacterium and a fungus belonging to the genus Fusarium 

 are together responsible for the trouble- 



This disease has been found constantly associated with wet, 

 soggy, poorly drained soils. 



Van Hook describes a bed enclosed with eight-inch boards, 

 four inches in ground and with the top of the bed very little if 

 any above the level of the walks. That portion of the garden 

 where the rotting was worst was shaded by an apple tree. The 

 garden was poorly ventilated, having two fences within, and one 

 on either side of a row of fruit trees. The soil was packed and 

 wet. This is an extreme case, but serves to show the chief condi- 



