On the Prevention of Curl and Dry-Rot in Potatoes. 1 73 
most (if not all) plants in greater perfection than land that has 
been in tillage, is tantamount to saying that in our ordinary routine 
of cropping some element or elements are removed from the soil 
which we do not restore to it in the manures which we apply. 
Hence it follows that the longer we continue such a repetition of 
crops and manures, the greater will be the deficiency of the sub- 
stances which we fail to supply, until at length some one crop, 
more dependent than others on those particular elements, tails to 
grow with its accustomed vigour, and is attacked by diseases and 
parasites previously unknow n. If all land were of similar quality, 
and had been treated alike in every respect, this falling off of cer- 
tain crops would have been simultaneously remarked on its first 
occurrence ; but with the infinite variety of soils, mode of cropping, 
and manuring which prevail on different farms, and even on dif- 
ferent fields of the same farm, the question is so complicated as to 
remain still doubtful. The remedy for this unavoidable (because 
as vet indefinable) deterioration of soil, is to resort occasionally to 
fresh land for seed, and to make use of every available variety of 
manure, until the advance of science shall enable chemists to 
point out the deficiency and suggest the remedy in each indi\idual 
instance. — 3rd. Change of practice. Another cause to which 
some little weight is due is the decidedly improved practice ob- 
servable amongst the farmers of the present day. They have 
better teams, superior implements of husbandry, and, stimulated 
by the more enterprising of their class, are less in the habit of 
dawdling over their seed-time, and thinking it of little importance 
whether they sow or plant a month earlier or later. It is rare 
now to see a man planting potatoes in the middle or latter end 
of June, though even yet I occasionally see an instance of it, and 
am told that a generation back it was by no means uncommon. 
Potatoes planted thus in the middle of summer on undrained, 
perhaps unenclosed, land, would, in ordinary seasons, be taken up 
unripe ; on the occurrence therefore of failure in the crop of a 
good stirring farmer, it would be easy for him to get seed from a 
neighbour whose potatoes grew well because they were late 
planted and badly ripened, and thus for a time the curl would be 
stopped. 
The foregoing remarks will make it sufficiently plain that 
the principal remedy I propose for the potato failure is the use 
of unripe sets. As, however, there are two ways of procuring 
unripe sets — one by planting late, the other by taking them up 
early — it may be w ell to point out some reasons for preferring the 
former plan. Potatoes that are taken up early have so great a 
tendency to vegetate during winter, that it is scarcely possible to 
prevent their being weakened by premature growth before the 
time of planting arrives. By planting late we not only avoid this 
