130 Mildew. [Sept., 



nured fields. If then, a period of rapid growth has existed and the 

 plant is surcharged with its natural juice, and there succeeds a dry- 

 scorching sun and winds which carry oti" the juices more rapidly 

 than they can be supplied by the roots, then the tissues dry; first, 

 the leaf withers and becomes black, followed by the same changes 

 in the limb or a portion of the limb, and it usually takes e t-ct 

 around the basis of a flourishing twig or branch, as we represented 

 in a former number of this Journal. The parts themselves which 

 are thus destroyed while in full sap, become, as we should expect, 

 black, and exhibit all the appearances of a gangrene or mollifi- 

 cation; these parts are never restored. 



It is to this peculiar disease we would restrict the term blight, 

 and although our theory of blight may not be correct; still our 

 description of the disease is sufficiently definite to enable any one 

 to think and speak understandingly of its effects and characters. 

 If our views are correct as it regards the cause, it may probably 

 be checked more by culture than by other means. We cannot, 

 however, well obviate the evils arising from too much water 

 which the root receives, and yet, if highly stimulating manures 

 predispose the plant to blight, it will be proper to give the less. 

 Facts, however, are wanting to enable us to reach a correct con- 

 clusion. And we leave it as it now stands for future investiga- 

 tion. We cannot even say whether deep drainage will be of any 

 avail, or drainage which shall carry off all the superfluous water, 

 and lay a field as dry as possible. A tree very rarely dies from 

 drought, though fruit is often affected by it — and it would be 

 only in extraordinary seasons, that fruit trees w'ould suffer by di- 

 minishing the amount of water in the soil by deep drainage. This 

 evil would be only an inconsiderable one compared with that of 

 the blight, and we hope that thorough drainage may be tried. 



MILDEW. 



Unlike blight, mildew is caused by parasitical fungi; fogs, or 

 dews are not the immediate cause of the malady, although we 

 think that certain states of the weather favor the developement of 

 fungi, and so may cultivation, or the want of cultivation; that is, 

 if a plant is not supplied with certain elements essential to a 

 healthy state, it is probable that mildew will attack it. Writers 

 describe several kinds of fungi which are parents of mildew; and 

 each plant seems to be infested with a S})ecific kind; and not 

 liable to injury from those which affect other plants, although 



