132 ON GRAPE M1I,DEW. 



VII. — On Grape Mildew. By Hugo v. Mohl. 



[Translated from the Botanische Zeitung, Jan. 2, 1852.] 



The attention of the readers of the Botanische Zeitung has 

 frequently been called to the disease which has attacked the 

 vines for some years in the west of Europe, and has been ex- 

 tremely injurious to tliem. Since this epidemic has passed over 

 the boundaries of Germany, and the history of its previous course 

 gives ground for fearing that it may spread widely amongst us 

 next year, some more particular account, which I am enabled to 

 give from observations made last autumn in Switzerland, may 

 not be vmacceptable. 



How far it deserves to be called a new disease may be left 

 undecided. Even supposing it to have appeared from time to 

 time in isolated spots, it must have been in a very trifling degree, 

 since it did not excite the attention of the cultivators of vine- 

 yards, and the fungus attendant on it was imknown to botanists. 

 It was calculated to attract the greater interest last year because, 

 after its first appearance at Margate (see Bot. Zeit., 1848, 

 p. 376), it gradually spread into France, where it appeared at 

 Versailles, in 1848 (see Bouchardat in Comp. Rend, xxxiii. 

 p. 145), the next year, to some extent, at Paris, and finally, in 

 ISol, reached the south of France, at the same time rapidly 

 travelling the whole length of Italy from tlie coast of Liguria to 

 Naples, then, as autumn approached, taking a retrograde course 

 through the Tyrol as far as Botzen, overrunning nearly the 

 whole of Switzerland northwards to Winterthur, and, at last, 

 trespassing on certain isolated points of Germany at the Hard- 

 gebirge, in Baden at Salem, and in Wiirtemburg at Stuttgart 

 and Cannstatf. 



On its first appearance in England, as also at Versailles, 

 Paris, and Grenoble, it seems to have been confined to the 

 vines in hothouses, and from thence to have spread to those on 

 walls, and, finally, to the vineyards. In districts where grapes 

 are cultivated exclusively in the open air, the disease in 1851, 

 in many places which I visited, as, for instance, in great part of 

 Switzerland and AViirtemburg, attacked those vines which were 

 grown on walls, and, where it had attacked the vineyards, the 

 bunches on the walls suffered far more than those on vines in 

 the open field ; and I was convinced that, in particular spots, 

 where the malady was at present much confined, it had passed 

 from the trellises to the neighbouring vineyards. It reached 

 the greatest heio:ht on those trellises which stand vinder the 

 wide-spreading roofs of the Swiss houses, and by which they are 

 protected from the rain. 



