Diseases of the Potatoe. 23 
each tuber had emitted shoots of three or four inches long. 
They were then carefully detached with their fibrous roots, 
from the tubers, and were committed to the soil: where 
having little to subsist upon except water, I concluded the 
cause of the disease, if it were the too great thickness of the 
sap, would be effectually removed, and I had the satisfaction 
to observe, that not a single curled leaf was produced; though 
more than nine-tenths of the plants, which the same identical 
tubers subsequently produced, were much diseased. 
In the spring of 1808, Sir John Sinclair informed me that 
a gardener in Scotland, Mr. Crozer, had discovered a method 
of preventing the curl, by taking up the tubers before they 
are nearly full grown and consequently before they became 
farinaceous. Mr. Crozer, therefore, and myself, appear to 
have arrived at the same point by very different routes; for 
by taking his potatoes, whilst immature, from the parent stem, 
he probably retained the sap nearly in the state to which my 
mode of culture reduced it. I therefore conclude that the 
opinions I first formed, are well founded, and that the disease 
may be always removed by the means I employed, and its 
return prevented by those adopted by Mr. Crozer. 
Another disease affects the seed, and is called the fatlure, 
or ¢aint, which consists of the destruction of their vital pow- 
ers. Many conjectures have been hazarded as to the cause 
of the failure, and most of them have ascribed it to the fer- 
mented state of the dung, to the drought of the season, to the 
heating of the sets, to the tuber being cut into sets, and other 
secondary causes; but all these conjectures leave untouched 
the principal consideration in the question, how these cir- 
cumstances should induce failure now, and not in by-gone 
years. Cut sets have been used for many years without 
causing failure. Farm-yard dung in various states of de- 
composition, has been used as long for raising potatoes. The 
extraordinary drought of 1826 caused no failure, while in 
comparative cool seasons the disease has made great havoc. ~ 
