84 



MYCOLOGY 



northwest, west and southwest. ' Now it is found in Connecticut, 

 New York, throughout New Jersey, and as far west as the Alleghany 

 mountains in Pennsylvania. In isolated areas, it occurs in Virginia 

 and West Virginia, endangering the future of the chestnut tree in 

 America (Fig. 27). 



Wherever the cultivation of the higher plants extends, the fungi 

 pecuUar to these plants will be found, as the wheat rust, Puccinia 



Fig. 27. — Map of the eastern United States showing distribution of chestnut 

 blight disease in 191 1. Horizontal lines indicate area with approximately all the 

 trees dead; vertical lines approximate area where infection is complete; dots indicate 

 advanced points of infection. {From Gager, after Melcalf, U. S. Farmers' Bull. 467. : 



graminis, in Europe, America and Australia. The damping-off fungus, 

 Pythium de Baryanum, which is death to seedlings, has been studied bj 

 German, English and American botanists, as a reference to the litera- 

 ture will show. The downy mildew, of the grape, Plasmopara viticola 

 apparently of eastern American origin, is found now in Europe and 

 California, where it has become a serious pest. 



The black knot, Plowrightia morbosa, was apparently at one timt 

 confined largely to the Atlantic seaboard and was particularly abundant 

 in New England and New York. It has now spread across the northeri 



' Cf. Stevens, Neil E.: Some Factors influencing the Prevalence of Endothi: 

 gvrosa. Bull. Torr. Bot. f'lub, .41 : 127 144, March, 11)17. 



