126 PRESENT STATUS OF THE INDUSTRY. 



for shading and constructing beds we had hoped to 

 replace the crop indefinitely. But nature has certain 

 requirements that man must recognize or meet with 

 disappointment. 



"Another forcible argument against succession of 

 crops is that disease and insect pests are likely to get 

 into the soil, and though perhaps the smallest, nema- 

 todes are by no means of the least importance. While 

 we do not know much about these minute creatures, 

 their work is plainly visible in the form of nodules 

 from the size of a turnip seed to that of a marble on 

 the fibrous rootlets. Enlargements are often formed 

 on the body of the root and around the neck also. 

 I have seen them as large as a hen's egg on the neck 

 of a root. When opened they show a large number 

 of minute red cells in which the nematodes breed, 

 though the outer surface is smooth and white. The 

 tendency is to impair the vitality and lessen the seed 

 production of the plant. In time softening and degen- 

 eration of the affected parts takes place, and ultimately 

 more or less decay of the root. We think they also 

 work in what seems like red rust on the bodies of 

 roots, where they form slight depressions; and in the 

 fibrous rootlets of old roots, destroying the entire 

 system of feeders, resulting in consumption of root. 

 We are coming to the conclusion that it may not be 

 possible to cultivate ginseng without nematodes. We 

 find them scattered over a considerable area, and not 

 only in garden culture, but also on wild roots and in 

 forest nurseries. Professor Slingerland says they are 

 found on clematis roots and that they are a great pest 

 in the German sugar beet fields. We have seen them 

 on sugar beets in this country. We would caution 

 against planting infected stock. When the nodules 

 are confined to the rootlets they may be picked off, 

 but, with all the precautions that may be taken, very 

 likely they, will be found when roots are dug for 



