700 JOURNAI. OF FORESTRY 



through a period of time, perhaps short but maybe long. At least 

 present indications are that it will require one rotation, or 30 years, to 

 render the trees practically immune after the disease has reached its 

 climax. Perhaps this period can be speeded up by keeping the sprouts 

 frequently cut back when small and thus having them longer in a 

 vigorous growing condition and favoring the immunization process. 

 But this might delay the process by decreasing the struggle. It is 

 worth at least an experiment on small areas. 



In order to show whether resistance is increasing sample plots 

 could be laid out in the older infected areas and examined at stated 

 intervals. Even repeated observation of a few young coppice groups 

 under average forest conditions would give definite comparative data. 

 It may take only a few years to get certain results but it may take 

 several decades. 



In conclusion the purpose of this article is suggestive and to encour- 

 age definite systematic observation on the basis of the hypothesis : that 

 chestnut is developing by natural processes immunity to the blight 

 through struggle zinth it. Further, that from present information, the 

 present stand of chestnut throughout its entire range is doomed; that 

 if chestnut survives it will be due to its sprouting capacity and to its 

 increase in resistance to the disease after the climax of the epidemic 

 has passed, with its complete destruction of merchantable material. 



REFERENCES ON RESISTANCE TO CHESTNUT BLIGHT. 



1. Metcalf, Haven. — The immunity of the Japanese chestnut to the bark disease, 



U. S. Plant Indus. Bur. Bui. 121:55-56, 1908. 



2. Fleet, Walter Van. — Chestnut breeding experience, Journ. Heredity, 5 :19-25, 



1914. 



3. Morris, Robert T. — Chestnut-blight resistance, Journ. Heredity, 5 :26-29, 1914. 



4. Anderson, P. J., and Rankin, W. H. — 'Endothia canker of chestnut, Cornell 



Univer. N. Y. (Agri. Exp. Sta.) Bui. 347, June, 1914, at pp. 533 and 534. 



5. Graves, A. H. — Resistance in the American chestnut to the bark disease:, 



Science, N. S., 48:652-3, Dec. 27, 1918. 



6. Collins, J. F. — Notes on resistance of chestnut to the blight. Phytopathology, 



10:368, July, 1920. 

 7. Anonymous. — Resistant chestnut, Am. Bot., 25 :25, 1919. 



