94 DISEASES OF GINSENG. 



examined, this fungus is quite constantly to be found associated 

 with the disease lesions, and may be isolated in pure cultures from 

 them. Observation has shown that limed gardens generally suffer 

 most from the disease and it is well known that this fungus thrives 

 only in alkaline soils or alkaline media. Unfortunately we have 

 not yet found time to make the necessary inoculation experiments 

 to establish the pathogenicity of this fungus on ginseng. How- 

 ever, its well known and established parasitism on the roots of 

 other plants together with the other evidence at hand, makes 

 almost certain what the results of such inoculation experiments will 

 be. It may be said, therefore (until disproven), that the Thelavia 

 hasicola causes the root lesions known commonly as "end rot", 

 "fiber rot", and "rust" or "scab." This fungus forms three kinds 

 of spores (seeds) as shown in (Fig. 42). The small hyaline conidia 

 produced rapidly in great abundance probably serve to spread the 

 disease from root to root through the soil, carried, perhaps, by 

 movements of the soil water, earth worms, etc. The large brown 

 conidia are resting spores germinating only after a period of rest, 

 several months perhaps in many cases. They thus serve to carry 

 the fungus over from one season to another in the soil. It is pro- 

 bably these spores, for example, that start the disease in seedling 

 beds. The ascospores, produced 8 in a sac or ascus, probably 

 serve also to carry the fungus over fi-om year to year. It will 

 thus be seen that the fungus is well equipped with means of pro- 

 pagation and perpetuation. These spores on germination send out 

 mycelium which penetrates the epidermis of the root and branch- 

 ing, spreads into the inner tissues, destroying them and bringing 

 them into this rotted condition. Being very small and numerous, 

 the spores are very readily transported on roots or in soil, and so 

 may be widely distributed. Moreover, as the fungus is probably 

 a normal inhabitant of many soils, it is probably naturally present 



