On the Potato Disease. 
377 
the colour does not become darker than usual, but remains of a 
darkish fawn. Of course a white potato should be used, not a 
purple one. I cut one in halves, scraping one half and grating 
the other, and there was considerable ditterence in the colour of 
them, much of the black tint being no doubt owing to the action 
of the acid of the potato on the iron of the grater. I am still of 
opinion, therefore, that, as so many potatoes have kept perfectly 
sound up to the present time, these had in no way imbibed the 
'principles of disease. 
If I have been right in attributing the late disease to atmos- 
pheric causes, it must follow, strictly speaking, that there can be 
no remedy for it in the power of man capable of general appli- 
cation. That must be left to One who has given its peculiar 
seasons to every land and its imalterable laws to the humblest 
herb. Still it is our duty to try every means. Lime and sulphur 
may in some cases under glass be of service in destroying mildew, 
but I have seen them tried without the least advantage as to 
curing the disease. The only elFectual remedy, if it may be so 
called, is to pull up the haulm entirely as soon as the disease has 
seized the stalks ; a great many potatoes were saved by those who 
adopted this method, although they will not be quite so good as 
if they were left to ripen on the haulm. Cutting off the haulm 
Avill not be so efficient in many instances, as the lower parts of 
the stalks are often as bad as the upper parts. Those who cut 
the haulm off before the spots appeared upon it, however, state 
that it was equally effectual. The above will, I believe, be the 
only means of mitigating the effects of the disease, if it should 
appear again, which I do not however in the least anticipate,* 
unless an equally ungenial season should occur, in which case it 
would probably be more severe ; and where persons have not been 
particular in planting sound sets, if on wet cold land, I have no 
doubt they will have a weak and gappy crop ; for, although I have 
raised healthy potatoes from diseased sets myself, and have seen 
the same produced by others, yet they are not to be relied on out 
of doors, as I have before experienced. 
Preventive measures are perhaps more in our pow er than re- 
medial, namely, to plant only sound sets in light open well- 
drained and well-prepared soil, with less manure than usual — for, 
as Miller truly observes, the wall-flowers which grow on old walls 
seldom rise so high, and have tougher roots, and firmer stalks, 
and smaller leaves than those which are planted in gardens ; but 
in severe winters, when these are frequently killed, those upon 
walls will receive no injury. And there can be no reason why 
potatoes grown on a poor light soil should not also become more 
* At present they look beautiful everywhere. 
