64 DISEASES OF GINSENG. 



diseased lesions. The seed hecids are commonly affected also. 

 The green half-grown berries show brown discolored spots, the 

 little stem bearing the berry becomes brown and shrivels and the 

 blasted berry falls (Fig. 24). This shelling of the berries, which 

 may occur any time up to the ripening, is often a puzzle to the 

 gi'ower. In practically all of these cases, which have been investi- 

 gated this shelling has been due to the Alternaria Blight. There 

 is so far no evidence that the disease ever directly attacks the roots 

 of the plant. It is distinctly an above-ground disease. It affects 

 the root indirectly 1:iy killing the toi)S, thus stunting or preven- 

 ting further root growth. Roots of plants that have blighted badly 

 one season appear never to recover fully from the shock, and even 

 though their tops for succeeding seasons are protected from the 

 disease, they never copipare favorably with plants of the same age 

 which have never suffered from the blight. 



CAUSE OF THE DISEASE. The blight is caused by a fungus 

 ( Alteriuiria jjanax Whetzel), a minute parasitic plant that lives 

 and grows within the tissues of the leaves, stems, and berries of 

 the ginseng plant. It pushes its root-like mycelium through the 

 leaf or stem tissues of the ginseng, killing the living substance of 

 the host and appropriating for itself the foods and juices thus made 

 available. From this mycelium it sends forth to the outside clus- 

 ters of short brown stalks, on the ends of which are produced the 

 seed-like spores (Fig. 1. in tig. 2.5), singly or in short chains of 

 two or more. Both the mycelium and the spores are very minute 

 and can be distinguished only by the aid of a microscope. The 

 spores are dark brown in color with cross walls in both directions, 

 dividing them into a number of small chambers or cells. Each 

 cell of the spores is capable of germination, sending forth, when 

 placed for an hour or so in water, a large sprout or germtube 

 (Fig. 26). These germ-tubes, if the spores be on a ginseng leaf or 



