On the Potato Disease 
491 
7 in 100 among seven varieties of manure, which consisted of — 
1, guano at the rate of 3 cwt. per acre ; 2, cow-dung, 20 tons per 
acre ; 3, refuse of manufactory, woollen dust, &c., 10 tons per acre ; 
4, horse-dung, 20 tons per acre ; 5, bones, 20 bushels per acre ; 
6, lime, 30 bushels per acre ; and soot, 20 bushels per acre ; 7, 
charcoal dust, 18 cwt., and wood ashes, 2 cwt., mixed, per acre. 
The guano, mill-dung, and horse-dung produced the greatest 
weight; the pieces manured with guano and with mill-dung pro- 
duced 10 in 100 that curled in the leaf and showing signs of 
decay ; those pieces manured with cow-dung, horse-dung, and 
bones, produced 8 in 100 with curled yellow leaves; those pieces 
manured with lime and soot produced 7 in 100 with curled leaves, 
but not to so great extent as the others; while the piece manured 
with charcoal and ashes had not a diseased leaf on it; the plants 
throughout looked of the most healthy and sturdy growth of any 
in the field, and the crop, though weighing less than the crops 
on the more highly manured ground, weighed more than the crop 
manured with soot and lime, and stored in a vastly superior de- 
gree to any other part of the field. In 1844 the whole piece was 
planted with mangold wurzel, and the piece on which the char- 
coal and ashes was used could be seen to a foot by the beautiful 
dark and robust leaves of the plants. I have not had the oppor- 
tunity of testing it upon potatoes to any extent myself, but we 
find in page 619 of the ' Gardener's and Land-Steward's Jour- 
nal ' a communication from Mr. Barns, gardener to Lady Rolle, 
of Bicton, stating that in some experiments he made with various 
manures, in 15 cases the only 5 lots of potatoes that were taken 
up sound were those manured with charred material mixed with a 
little soot and lime. 
Fourthly. Give plenty of room, so that the air may have free 
access to the foliage to dry off any damp that may be lurking 
about it; this point is of the utmost consequence, as all my ex- 
periments and observations have fully proved to me at least. In 
1845 I planted a piece of ground with potatoes, on one part of 
which the rows were 3 feet apart, and on the other part 2 feet 
from row to row ; I tried this experiment not with a view to see 
which would be most healthy, but to decide a dispute about which 
would produce the best crop and the best sample. The part 
where the rows were 3 feet apart yielded 5^ pecks per rod, and 
the part where the rows were 2 feet apart yielded 5J pecks to 
the rod ; ihe first were affected with the disease at the rate of 
1 in GO, and the second at the rale of 1 in 1 5. 
These then seem to me the four points we have to build upon 
in endeavouring to mitigate though we may not avert the future 
progress of the disease. 
With regard to the treatment of the tubers in planting, I can 
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