488 
On the Potato Disease. 
of management ; one appeared exceedingly vigorous and thick, 
the haulm having run into a mat ; they covered the ground almost 
as thickly as vetches ; those had been planted whole, and the rows 
not more than 20 inches apart ; it was a white variety with 
numerous eyes, which threw up several stalks from each tuber : in 
some cases I observed that the tops had grown to the length of 
54 feet, and were of course prostrated. I need not add that their 
leaves were all rotten before the plants were full grown, except a 
very few leaves on the tops; when they were taken up the roots 
measured 2 pecks to the rod ; three out of four of which were 
nearly rotten, and all the remainder affected. 
The other lot was planted with the same variety and at about 
the same time ; but the man, being short of seed, had made, 
contrary to his usual practice, a set with nearly every eye, and 
planted them 30 inches by 12 apart, — that is, he put his rows 
2^ feet distant from each other, and the sets in the rows 12 inches 
from each other ; consequently, having plenty of room, the stalks 
grew strong and erect, and the ground was not covered with them, 
so that the air could circulate freely about them. This piece, 
although it looked what we call thin, produced 5 pecks to the 
rod, and not more than one tuber in twenty was the least affected. 
I could adduce numerous instances similar to this, but I think this 
sufhcient to pi'ove that cutting potatoes for sets has nothing to do 
with the disease in question. 
It has been urged that the weather had nothing to do with the 
disease, because it had been known before even in the previous 
dry season. Certainly I have myself seen it formerly and in many 
instances. In the year 1842 I had some potatoes sent me for 
Ash-leaf kidneys, which turned out to be mixed with a variety 
called the Purple-cut kidney : they were planted on a piece of 
rich ground, and all came up strong ; the Purple cuts, however, 
soon got the advantage of the Ash-leaf, and at last completely 
overran them, so that the Ash-leaf were kept perpetually in the 
dark and damp: the stalks of the Purple-cut variety, from being 
planted in a damp and rich spot, grew in some instances 8 feet 
long. Upon taking up the crop there appeared several dark- 
brown spots which spread rapidly over the potato, precisely in the 
same way as the spots of 184.5, after being exposed to the sun. 
In the same year my Dutch potatoes, planted the beginning of 
August for the purpose of digging as a substitute for young 
potatoes in winter and spring, were also affected with precisely the 
same disorder ; and I have found it in this variety for several 
vears, which I attribute to the damp cold season setting in while 
the stems and foliage are in so tender a state ; I have never 
observed it when they have been clean cut down with a sharp 
frost and their vegetation stopt at once. In 1843 I saw a })it 
