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A little-known Mildew of the Apple 



By a. T. Grout 



(With Plate 364) 



Late in the autumn of 1892 (November) a mildew was ob- 

 served on a few belated leaves clinging to the adventitious shoots 

 from the stump of a young apple tree in Newfane, Vt. The shoots 

 were gathered and the leaves closely examined for perithecia, but 

 none could be found. An accidental examination of the twigs 

 showed that the mycelium had spread over the upper portions 

 and here and there were darker spots covered with more closely 

 matted mycelium. Under the microscope these spots were found 

 to contain abundant perithecia, like those figured in plate 364, figs. 

 I and 2. At that time I found no one in New England who 

 knew this mildew. It was, however, described in Ellis and Ever- 

 hart's North American Pyrenomycetes (then recently issued) as 

 Sphacrothcca mali (Duby) Burrill. Prof. Burrill there remarked 

 that he had not had access to any European material of this fun- 

 gus that was at all satisfactory, but from the description and the 

 fact that it was scarcely possible that the introduced Pyriis Mains 

 should have an exclusively American parasite of this kmd, he 

 concluded that the American plant was the one described as Ery- 

 .y;///^' w^/^' Duby, Botan. Gall. I : S69. 1830. 



A careful examination of the exsiccati in the Harvard and 

 Columbia herbaria, including the Ellis herbarium, failed to bring 

 to light any European material of Bysiphc mali Duby which con- 

 tained perithecia in condition to be of any use. The European 

 exsiccati contained leaves only, while the perithecia In the Amer- 

 can plant were invariably found on the young twigs. 



In 



M 



M 



Berichte der Deutschcn botanischen Gescllschaft a historical and 

 descriptive account " Ueber eincn in Sudtirol aufgetretenen 

 than des Apfels " in which Professor Magnus completely confirms 

 Professor Burrill's conclusions. As his article and plate will be 

 accessible to comparatively few in America, this article and an en- 



(37:5) 



