196 CaiLse of the Potato Disease. [Oct., 



FACTS WHICH SEEM TO BEAR UPON THE CAUSE 

 OF THE POTATO DISEASE. 



The same week when the potato-vine exhibited the first in- 

 dication of disease, many trees in the vicinity of Albany were 

 affected in a manner similar to this plant. The leaves of several 

 elms for instance began to dry and grow brown upon their edges, 

 and in a few days it terminated in the death of those leaves, when 

 they fell off. Besides the elm, a few maples, horse-chesnut, plum, 

 bass, button-w^ood, and the vine, were affected in a manner quite 

 similar to the elm. It did not appear that all the individual trees 

 of the same species were attacked w4th this kind of blight. 

 Those individuals however, whose leaves were rather succulent or 

 juicy, were most liable to this affection. 



This affection of the leaves, inasmuch as it came at the time 

 we were first visited with extremely hot weather, and which was 

 accompanied at times with a hot south w^ind, must be attributed 

 to this peculiar state of the weather, or to an atmospheric influ- 

 ence. Several elm trees, and many button-woods .have died, it 

 would seem from the effect of some malady which has attacked 

 in the first place the leaf. The operation of the malady is simi- 

 lar upon the potato plant. It has been observed that the most 

 tender leaves dry upun their edges; the dryness extends soon to 

 the whole leaf, but the most vigorous part of the herbage resists 

 the attack the longest; but as the plant itself is gradually weak- 

 ened by loss of the leaves, the whole herbage after a while dies. 

 The tree however may and does resist for two or three seasons, 

 the branches dying successively. The approximate cause of the 

 death of the leaf, seems to be a dry, hot, and parching atmo- 

 sphere: it may perhaps be only a predisposing cause. Real 

 causes of disease are obscure; when, however, antecedents and 

 consequents are so closely connected tis in the cases we have 

 been considering, we cannot refuse to give or attribute to the 

 phenomena considerable importance, especially when they pre- 

 serve the same standing and relation for several years in succes- 

 sion, as is the case with those affections of trees and potato 

 plants. 



