April; '12] CHESTNUT BARK DISEASE DISCUSSION 227 



Mr. Berger (Florida). Does this disease act to anj' extent on 

 other trees? 



Mr. Metcalf: The Chinquapin is absolutely subject to the 

 disease and that species will take the same course as the chestnut 

 tree. The Japanese Chestnut is highly resistant; so much so, that 

 at one time it was thought to be immune to the disease. The Korean 

 chestnut appears to be also highly resistant. The European varieties 

 of chestnut are apparently quite as susceptible as American species 

 and varieties. 



A Member: Where does this disease come from? 



Mr. Metcalf: That is exactly what we would like to know more 

 about. The fact that the disease has obviously spread from a cen- 

 ter, leads me to believe that it is an importation rather than a 

 disease wMch has developed here. The fact that the locality from 

 which it has spread is the same locality into which the Japanese chest- 

 nut was first extensively introduced; that the Japanese and Korean 

 chestnuts are highly resistant and are the only varieties that are at 

 all resistant — all suggests the hypothesis that the fungous parasite 

 may have come from the Orient. However, the origin of the parasite 

 is not a matter of practical importance unless it could be showTi that 

 the fungous parasite is developing spontaneously in many localities 

 from some native saprophji:ic form, in which case the difficulties of 

 control would be greatly increased. This suggestion is, however, so 

 far-fetched that we do not need to consider it seriously until some 

 facts are adduced to support it. The main fact is that the disease 

 is here, and it is up to us to decide whether to fight it with the best 

 means we have at hand or to let it go. 



A jVIeaiber: What are the fundamental principles of natural 

 inoculation? 



Mr. Metcalf: We are not sure that the disease can enter a tree 

 in any way, but through wounds. Any of you who are familiar with 

 the chestnut tree, know of the injuries made by various kinds of insects. 

 I have not the slightest doubt that in ninety per cent of all cases of 

 this disease, the fungus found entrance through lesions made bj' insects. 

 The spores are sticky in character and may be transmitted by water, 

 by birds, by insects, and to a large extent bj^ human agency; doubt- 

 less also in other waj^s. 



]\Ir. Fernald (Mass.): From what we have said, does it not 

 follow that in case this disease is found present on nursery stock 

 there is only one possible treatment, — the absolute destruction of the 

 tree? 



'Sin. jMetcalf: — This is unquestionably the case. I think the 

 specimen here shows the characteristic form of the disease on nursery 



