ON GRAPE MILDEW. 137 



fectly incapable of answer. The prospects afforded by its pre- 

 vious history are by no means comfortable. We have to contend 

 with an enemy against which, as regards its diffusion, we are 

 perfectly powerless, since every breeze may bring thousands of 

 its minute microscopic germs from an infected district to one 

 which is at present untainted. Nor less is any notion of tlie 

 destruction of the fungus on the diseased vines, by washing, 

 fumigation, &c., in places where vines are extensively cultivated, 

 completely out of the question. Under these circumstances 

 there reniains only the by no means powerful consolation that, 

 as in analogous diseases produced by other fungi, even though it 

 may not entirely vanish, it may be expected to be at all widely 

 extended, and, consequently, decidedly injurious, only in certain 

 years. A remedy is the more difficult, or rather the more im- 

 possible, because it relates to a woody perennial plant, and there- 

 fore a multitude of variations in the mode of culture which are 

 available in annual plants, as different ways of planting, the 

 choice of a favourable site, rotations of cropping, &c., are 

 clearly inapplicable. It appears also that all such remedies as 

 depend on variations of culture, even were they more easily 

 applicable to the vine, would not be crowned with much success, 

 since, at least as far as my own experience goes, no particular 

 rules are deducible from the condition of diseased vineyards, 

 according to which the occurrence of the evil is regulated as 

 regards the exposure towards a particular quarter of the heavens, 

 the geological nature of the subsoil, the lower or higher training 

 of the plants, the age of the vineyard, the circumstance whether 

 it had been recently planted on virgin soil, or was of the growth 

 of many centuries, &c., since none of these points seem to have 

 the slightest influence, and only in particular spots, a low situ- 

 ation and the moisture of the soil, appear to be favourable. Al- 

 though particular kinds of vines, as the crowfoot (Trollinger) and 

 muscatels, suffer extremely, this is but a proportional difference, 

 since in other places sorts of the most various nature were 

 attacked ; and even should experience clearly prove the especial 

 tendency of particular varieties to contract the infection, this 

 point could scarcely induce any great alteration in the cultivation 

 of the vine, as the choice of sorts depends upon so many other 

 circumstances. 



At least for the present what is possible to be done in the way 

 of alleviation must be confined to culture on a small scale in con- 

 servatories or on walls, since the small quantity of vines Avhich 

 are cultivated in such situations admit of some special treatment. 

 These situations are moreover, as was remarked above, the most 

 perilous, because they afford the most favourable ground for the 

 malady, and form the centre from which it extends to the vine- 



