Observations upon the Potato Rot. 23 



It has been said that the leaves are first affected ; and that 

 the withering of these leaves, as if they had been struck by a 

 blight^ is the first sign or warning of the presence of the de- 

 stroyer^ But I am inchned to doubt the correctness of this 

 statement. The first indication of the presence of the disease, 

 is upon the haulm or stalk. This, if carefully examined, will 

 be found to be covered with mmute black specks, strikingly 

 resembling in appearance the excrement of the fly, and visible 

 to the naked eye. These specks are a species of fungus, 

 which attacks the plant, in most cases very suddenly, and 

 which, in my estimation, is the chief cause of the rot. As 

 soon as their roots (for they are parasitic^ have penetrated 

 through the cuticle of the stalk, the sap, from Avhich they 

 derive their nourishment, becomes vitiated, and the withering 

 of the leaves is the immediate consequence. This withering 

 of the leaves affects the health of the plant, and renders it 

 more susceptible to the attacks of the fungus. Soon the pith 

 of the stalk becomes diseased, and, if examined with a lens, 

 will be found to contain many of these black specks, showing 

 that the fungus is there. Finally, it extends down the stalk 

 to the roots, or parts cormecting the stalk with the tubers. 

 These roots are completely hollowed out by the fungus, or in 

 other words, their interior is entirely destroyed, or, eaten up. 

 The skin of the tuber is next attacked, and this becomes dis- 

 colored. By lifting up the skin carefully, and examining tiie 

 tuber with a lens, the same black specks will be found, show- 

 ing that the fungus is there. Last of all, the roots of the 

 fungus penetrate the cells of the tuber, destroy their texture, 

 and, by breaking down their walls, the contents of contiguous 

 cells are brought together, and corruption, or putrifaction 

 ensues. This is the last stage of the disease, or the 7'ot. The 

 above is a brief sketch of the progress of the disease, which I 

 have endeavored to clothe in language comprehensible by 

 every farmer. 



In harvesting a field of potatoes, those who have carefully 

 noticed the appearance of the stalks, have been able to tell 

 what hills were affected by the rot, and what were not ; and 

 not only so, but the same observation enabled me to tell what 

 tubers in any particular hill were affected. The stalks of 

 those hills which are affected, are rotten at the bottom, near 



