CHESTNUT BARK DISEASE. 453 



than Diaporthe. It has two saprophytic or semi-parasitic 

 relatives in this country, known as Endothia radicalis and 

 Endothia gyrosa. The latter also occurs on chestnut, and the 

 chestnut blight, being very similar morphologically, has been 

 referred to it by the writer as a parasitic variety called Endo- 

 thia gyrosa var. parasitica. Others have considered the two 

 as entirely distinct species, and still others as forms so closely 

 related as to be identical morphologically. 



(5) While no record, either here or abroad, has been found 

 of any previous outbreak of the blight fungus, there have been 

 reported at different times in the past century unknown chest- 

 nut troubles in the southeastern United States that possibly 

 may have been due to it. 



(6) The blight fungus has been considered by Metcalf as 

 an importation from Japan, and by Shear as introduced from 

 Europe, while the writer maintains that it is a native fungus, 

 which, because of peculiar conditions detrimental to the host, 

 has assumed unusual virulence and widespread prominence. 



(7) These conditions unfavorable to the host were in part 

 the unusually severe winter of 1903-04, which injured trees in 

 general in the northeastern United States, and after which 

 the blight suddenly made its appearance, and in part the sub- 

 sequent unfavorable seasons for trees, especially the last 

 four or five years, when summer droughts were unusually 

 severe. 



(8) If the writer's conclusions are correct, then it is useless 

 to try to make a widespread fight against the fungus, since it 

 will, under conditions favorable to the host, return in time to 

 its former inconspicuous parasitism. If they are incorrect, 

 it is still a question whether or not the cutting out and 

 quarantine method is effective and can be carried on so 

 economically and extensively as to be of practical value. 



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