Graves: Diseases of Trees in New York 



113 



Melanconium oblongiim Berk, has been collected many times 

 in the U. S., but almost entirely, so far as the writer can ascer- 

 tain, on Juglans cinerea.^ Berkeley first described it from speci- 

 mens from the United States in 1873-4.^ From an examination 

 of published descriptions of Melanconium species and from a 

 study of exsiccati we suspect that the organism has several aliases, 

 but until the criminal evidence is more conclusive it is not worth 

 while to discuss them here. Dr. Shear collected the fungus in 

 1893 in close association with Diaporthe jitglandis E. & E., and 

 according to a note by him in the herbarium of the N. Y. Botan- 

 ical Garden, he believed the latter species might be the perfect 

 form of Melanconium oblongum. 



The spores of the fungus are brown, elliptical-oblong, with 

 homogenous granular contents, or often containing one or more 

 drops or vacuoles, and measure about 20 fx in length. 



It is possible that the fungus may prove to be a slow parasite, 

 but of course the only evidence in support of this is its constant 

 association with the disease. However, another species of this 

 genus, Melanconium sacchari, is usually accredited with being 

 the causal agent of a destructive disease of sugar cane.* There 

 is need of further work, particularly inoculation experiments, to 

 throw light on the question.*^ 



IL Nectr.ia Canker OF THE Sweet Birch (5^^///a/£'n/aL.) 



This was easily to be reckoned the most destructive disease of 

 the sweet birch in the New York area, and is causing a great deal 

 of damage. The writer has had the trouble under observation 

 since 1909, having first observed it in a forest at Orange, Conn. 



2 Collected by Ellis at Newfield, N. J., on Juglans regia, 1892. The writer 

 has made an effort to find the fungus on Juglans nigra L., but without success. 



3 Berkeley, M. J. Notices of North American fungi. Grevillea 2: 153. 

 1873-4- 



4 Cook, Mel. T. The diseases of tropical plants. Pp. 81 ff. New York, 

 T913. 



4a Healthy twigs of butternut, brought into the greenhouse in March, 1919, 

 and inoculated from a pure culture of the fungus, had, on April 26, as this 

 paper is going to press, developed 33 infections out of 59 inoculations. 19 

 of these 33 showed spore pustules of Melanconium oblongum. Checks re- 

 mained uninfected. A similar series on black walnut gave negative results. 



