January 28, 1892. ] 
JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. 
69 
leaves of the Potatoes, never later than the beginning of the 
harvest. This can be done with a hoe in allotments, or with a 
plough in fields, and should cover the tubers on both sides of the 
row not less than 4 inches thick with fine mould. Now the 
previous moulding having been round or flat on the top, next to no 
hollow is formed, as in ordinary moulding, or if there is the top 
must be rounded. That is not mentioned in the “ instructions,” 
but we consider it necessary that the conidia be given no place 
about the stems, but as in the first moulding give them a chance 
of being washed into the furrows, and there spending their forces 
on “ desert air.” At the same time as the “ protective moulding ” 
the tops are to be bent over to one side of the row, there to scatter 
the conidia, not over the tubers, but on the moisture of the furrows, 
and when the tops begin to wither, most of the leaves having 
fallen, they are to be cut off, removed, and burnt. In the course 
of a few days the tubers may be lifted, and Mr. Jensen recom¬ 
mends disinfecting them—at least the seed tubers—by placing 
them for four or five hours in a dry-air chamber at a temperature 
of from 100'’ to 105°. This system is based on the principle that 
the conidia and the zoospores are w^ashed by rain from the leaves 
to the soil, and through the soil on to the tubers. The plan is in 
some respects much older than the Potato disease, for double 
earthing was practised in the warp lands of Lincolnshire and 
Yorkshire before its general prevalence in 1845. The first earthing 
was small, the cultivator striving to help the crop by giving the 
plants a little warm sweet soil whilst getting the sun into the 
ground for forwarding the crop later on ; and the second earthing- 
up was to prevent the drought getting into the earth and save the 
tubers from greening. More, to secure fine, more saleable tubers, 
fewer “chats,” the tops were drawn over into the furrows, and this 
let the sun into the tops, and these, in more light, and the tubers 
having more heat, had more starch within them—flour balls little 
less nutritious than wheaten loaves. Then the tubers were sweated 
—placed in “ pies ” (several hundred yards in length in many 
cases)—and the superfluous moisture expelled, a drain-pipe being 
inserted at the apex at every 4 to 6 feet distance, or a “ straw 
chimney” placed through the covering of straw, and a little 
earth to prevent its displacement, let off the steam. The system 
answered well before the disease was generally known—it has 
answered well since wherever it has been adopted. 
The offering by Earl Cathcart, through the Royal Agricultural 
Society, of £100 for an essay on the Potato disease, resulted in an 
expression of opinion that the Potato plant was weakened by 
continuous propagating from the tubers, therefore liable to fall an 
easy prey to the fungus, more so than varieties raised from seed, 
and it was recommended to raise varieties by that means such as 
would resist disease. That, no doubt, resulted from the well 
known fact that some varieties were hardier and more disease- 
resisting than others. The outcome was the withholding of the 
£100, no award being made ; but, if the essayists received no 
satisfaction from the Royal Agricultural Society they have had 
the consolation of not labouring in vain, for cultivators and con¬ 
sumers have profited by the introduction of new and disease- 
resisting varieties of Potatoes ; to wit, Magnum Bonum and 
Scotch Champion, with others better in some respects than the 
older varieties. 
Then, attempts have been made to supplant the varieties of 
Solanum tuberosum by other tuber-producing species of Solanum. 
The efforts have not been successful so far, though some have 
beeh found, as S. Commersoni, resisting or uninjured by Phytoph- 
thora infestans, that spenies and S. Maglia proving most promising, 
yet they are a long way from becoming substitutes for the Potato, 
and when they are improved by cultivation, who knows whether 
they will be disease-proof ? No variety is under all circumstances 
and in all conditions disease-proof, therefore it is a question of 
combating the diseases, and those enemies to which cultivated 
plants are subject, if we mean to have the continued use of their 
products. 
Prevention. —Sulphate of copper, or blue vitriol, has long been 
used on the Continent, first, I believe in France, as an annihilator 
of fungoid parasites on Yines, and in recent years has been 
experimented with there and in America for the prevention of 
diseases of fungoid origin, and the results have been such as to 
leave no doubt that the copper cure, as it is called, is efficacious, 
and with due care perfectly safe. The sulphate of copper 
dissolves in four parts of cold water and two of hot water. It is 
insoluble in alcohol, but readily dissolves in ammonia. Indeed 
copper salts are characterised by their tendency to form com¬ 
pounds with ammonia, an excess of ammonia added to a solution 
of copper sulphate resulting in a deep blue solution of ammonio- 
cupric sulphate. Aramoniacal solutions of copper are not, however, 
about to be alluded to, and they are only mentioned for avoidance 
in treating the Potato, for ammonia is as bad for blackening 
Potato tops—though it will not cause the tubers to rot—as the 
Potato fungus, and the sulphate of copper has a very offensive 
styptic taste, and is extremely poisonous. That must be kept in mind 
in treating the Potato disease, and raises a very important question. 
Is copper sulphate safe to use against the Potato disease ? Dr. 
Haselhoff, the German scientist, has pointed to copper salts being 
a possible source of danger, and shown that the dry substance of 
plants grown in soil impregnated with copper sulphate to decrease 
in proportion to the quantity of that salt present. Against that we 
have to place the facts that in France, where it has been used 
longest, and in America, where it is generally used for preventing 
attacks of parasitic fungi, no injurious effects have been experienced 
by cultivators, but on the contrariwise good benefit has resulted, as 
the British grower knows to his cost by the much finer and cleaner 
fruit American growers send to British markets, and no evil con¬ 
sequences have followed the consumption of produce, the plants 
producing it having been kept free from parasites by the judicious 
employment of copper sulphate. 
The Mixture. —Copper sulphate in simple solution with water 
is so styptic (and that means antiseptic) that it is not safe to use 
on tender foliage at a strength of 1 lb. to 25 gallons of water. At that 
strength it may destroy oospheres, but the evidence points to treat¬ 
ment of the “fruit” as not benefited, that is, from the cultivator’s 
point of view—namely, destroyed. Nothing less than a 1 per cent, 
solution, 1 lb. of sulphate of copper to 10 gallons of water, having 
that effect on the “outer coat” as to kill the oosphere within it. 
No plant will stand the solution at that strength unless ligneous 
and quite dormant, therefore treatment before growth for the 
destruction of “ rests ” is totally inapplicable to the Potato. Nor 
does iron sulphate afford any shelving of the disease, for to destroy 
Potato disease “ rests ” a 50 per cent, solution at least is necessary, 
and no plant like the Potato will stand that, whilst a 6 per cent, 
solution of iron sulphate has proved innocuous against the 
phytophthora, therefore we may dismiss iron sulphate or green 
vitriol as ineffective, no use, in fact, in regard to the fungus, how¬ 
ever well it may serve the Potato plant internally in resisting its 
enemy from without or in repelling invasions. Thus we have to 
fall back on copper sulphate, and that is no use in simple solution, 
consequently we must take off its styptic properties, make it 
oxidise slowly and in such manner as not to injure the Potato, yet 
powerful enough to destroy the oospheres, conidia, or zoospores of 
the fungus. A 6 per cent, solution when hydrated with lime is 
too much for the Potato tissues, blackening them, and a wrongly 
compounded 2| per cent. Bordeaux mixture is quite as disastrous 
as the fungus, whilst a stale mixture is neither good for the Potato 
foliage nor the soil (if the German scientists are right), or harmful 
to the fungus. If stale air slaked lime is used the copper sulphate 
is as styptic and hurtful as the simple solution, killing or seriously 
damaging the Potato plant and decreasing the yield of Potatoes. 
When the mixture is prepared beforehand it has no effect on the 
fungus, but it may injure the plant, though that is uncertain, and 
is no use whatever, worse than useless, material wasted, labour lost. 
Proper Formula of Bordeaux Mixture for the Potato 
Disease. —Sulphate of copper, powdered, 2f lbs. ; quicklime, light 
lumps fresh from the kiln, 2f lbs. ; water, 10 gallons. Place the 
powdered copper crystals in a tub, pour in 3 gallons of water, 
stirring until the water is blue. Pour the blue solution into an 
empty tub, and 3 gallons of water into the tub containing the 
copper, stirring the latter as before. This will dissolve all the 
copper sulphate, when pour this also into the other tub. Place 
the lime in the empty tub, slake with water, and add enough water 
to make a thin whitewash. Pour the whitewash into the copper 
solution through a coarse sack stretched over the top of the tub. 
This removes all small pieces of lime and dirt. After pouring in 
all the whitewash, add the remainder of the water—10 gallons in 
all being used—and thoroughly stirred, the mixture is ready 
for use.—G. Abbey. 
(To be continued.) 
A Sheffield Dinner. 
When a Journal representative received instructions to go and 
attend a dinner a few days ago he bowed to the call of duty as readily 
as Mr. Archibald Forbes, when that brilliant war correspondent was 
instructed by a laconic telegram to “ Go and do the Zulu war. Bu> 
“ the way was long, the night was cold,” and perhaps he had dimcuLty 
in repressing a shiver or two at the prospect of a journey of 1^ miles 
to eat his dinner in the grey gloom of a frosty January day. By-and- 
