194 



JOUKNAL OF HORTICULTURE AND COTTAGE GARDENER. 



[ March 14, 1867. 



my trouble, for anything more beautiful in the way of fruit- 

 bearing than these hitherto-barren trees I have seldom looked 

 upon. They were, both when in fruit aud blossom, the admira- 

 tion of all who saw them. 



Since the pinching plan has been adopted upon the trees in 

 question, no winter pruning has been necessary, and they are 

 showing now every livelihood of being, with the permission of 

 the sparrows and the spring frosts, us abundantly fruitful in 

 1867 as they were in 1866. — Beta. 



In a communication from a correspondent signed ".T. T.," 

 en propagating and pruning Black Currants, I am not a little 

 surprised to find him saying, " The Black Currant likes plenty 

 of sun and air, and does not succeed so well as the Red Cur- 

 rant in the shade." So far from sun and air being indispen- 

 sable for the successful cultivation of the Black Currant, and 

 so far from its requiring in all cases the treatment which he 

 describes, I give an instance to the contraiy. The sun's rays 

 never reach the Black Currant bushes planted in the orchard 

 here, quite under the shade of Apple and Pear trees, from .June, 

 when the trees are in full leaf, until after the fruit is gathered, 

 and ."ill who see the produce declare they never saw such fine 

 Black Currants. The bushes bear immense crops of large, 

 equal-sized berries. 



My object in biinging this f&ct under the notice of your 

 readers is that they may be encouraged to plant any garden 

 ground that may be shaded, with the utmost confidence of 

 success. 



It may interest your readers to know that plants of Cineraria 

 maritima, without any protection, have withstood the late 

 severe winter in an open border on the east coast of Scotland. — 

 H. R., -F'/c. 



CAUSE OF THE POTATO DISEASE. 



I AM fond of Roses, no one can be more so, and Mr. Ead- 

 clyffe is fond of Roses ; but, then, if he were to grow a mul- 

 tiplicity of Potatoes, he could not find sufficient room for 

 Roses ; and if I were to cultivate as miiny kinds of these as 

 Mr. Radclyffe does, I could not find siiflicipnt room to grow 

 and study the more lowly, though valuable. Potato. I am no 

 final-cause man either ; to me it would be distressing not to 

 think of beyond. 



However, I am called upon by Mr. Radclvffe, at page 144, to 

 enlighten him upon " the great mystery of the natural world ;" 

 but I wish he had deputed the task to more competent hands. 

 1 always held that the spot on the leaf was the cause of the 

 gangrene in the tuber; but nature's laws generally admit of 

 two methods of inquiry, philosophers call them Induction and 

 Deduction — ways leading to the same end by different tracks. 



In the first year of the disease I was living at Stanton Lacy, 

 near Ludlow, and we had a large piece of ground planted with 

 a then favourite Potato of mine, called the Birmingham Blue. 

 I prided myself on the appearance of the croj). and had almost 

 begun to calculate the money it would return in the shape of 

 bacon when consumed by the pigs, when the lightning and the 

 thunder came, and in a few days afterwards the tops of the 

 Potatoes were black and offensive in their odour. From annual 

 observation ever since, I have invariably found that the leaves 

 of Potatoes show the fatal spot in close thundery weather ; 

 merely wet or damp weather does not cause the leaves to 

 become atlected, aud I have never found the tubers diseased 

 when the foliage has escaped being smitten by, as I believe, 

 the electric fluid. For instance : last season the haulm of the 

 Early Ten-week was ripe and gone before the lightning came, 

 and although I allowed the crop to remain in the ground side 

 by side with the other kinds to the last, not a single tuber 

 became affected. The conductors rrere not there ? Those 

 ■which remained of the first-early Potatoes raised on warm beds, 

 escaped also for the same reason. Not so the produce of the 

 sample of the very same seed and sorts in the garden. Their 

 tubers became affected more or less, as I have already stated, 

 in consequence of the foliage being sufficiently immature and 

 green to allow it to become stricken. I have always found it to 

 be so, and this seems to me reasonable ; for at the mid-state 

 of growth the system is eager and susceptible, and the sap 

 which feeds the roots then descends in its fall flow ; should it -^ 

 become vitiated at this time — it is at a mid-state that the i 

 disease shows itself— in the leaf, through the agency of some | 

 poisonous gas as yet unaccounted for in the atmosph' i' ''e , 

 upbole system of the plant aud the tubers must become uiitcily i 

 affected ; and when the Potatoes are growing upon a wet un- 



drained soil, or where raw manure is overstimulating their 

 growth, so sure in those cases is destruction to be more fatal. 



Now, as the Potato disease is sure to visit us annually more 

 or less, and the later the better, and as it will ever be an im- 

 possibility for any chemical labour to prevent the atmosphere 

 becoming charged with electricity, the wisest plan (or us to act 

 upon is to try and combat the disease by good cultivation. We 

 must not give way to the too-common habit of allowing the 

 soil to lie soddened, uncared for, and ovcnun v.'ith weeds and 

 by all the children until the last moment in spring, when a 

 hundred other matters require attention, to be then hurriedly and 

 improperly dug, and to be planted in a similar manner. Worse 

 still, the Potatoes themselves are too often subjeeted to a like 

 careless treatment ; they are, probably, kept in masses, heated, 

 forced into germination, and deprived of their long premature 

 shoots over and over again, till almost all the strength of the 

 tubers is exhausted; then, as a final stroke, with some cruel 

 crooked instrument, they are cut to pieces and placed along 

 with raw manure in drills at planting, thus adding as it were 

 insult to injury, and laying the surest foundation for disease 

 that could possibly be thought of. Almost to a certainty it 

 was this sort of ill-treatment which weakened the Potato in 

 the first instance, and laid it open to attack. Eschew the 

 practice as you would avoid the plague. 



I may be thought to allow too much fancy to mix with my 

 reason. I answer, that for the unknown phenomena of the 

 disease the naturalist must sometimes theorise. If all the 

 facts were known, nothing would be wanting but an appeal to 

 reason. Imagination and appearances combined with experi- 

 ment must be the landmarks, and this is the utmost I can 

 offer by ways of elucidation. Tli^ cause will, doubtless, some 

 day become scientifically known, be worked out in the chemist's 

 laboratory, in the same way as hundreds of other hidden things 

 in nature have been unfolded to us ; and we need not consider 

 it strange that this has not been done yet, for, to bring the matter 

 home, it is not so very long since the real nature of glass and 

 soap became understood through chemical investigations. Dis- 

 coveries, too, are repeatedly made by men knowing nothing 

 about chemistry. 



I wish Mr. Radclyffe every success in his experiments with 

 the dissolved vitriol, though I fear it will prove a failure in 

 respect to eradicating the disease. No doubt it will kill the 

 fungus on the tubers, and so it would on the leaf, though in 

 my opinion the mischief is done before the fungus appears. I 

 think the latter is an effect, and not a cause of the disease. 

 Stephen's conclusions, however, are all true, except, perhaps, 

 as regards the " skulkers." I should not feel so sure of them, 

 and I do not like skulkers, but, honour to Stephen. 



I will, in conclusion, quote a passage from a paper by Liebig 

 (to whose writings and those of other scientific observers I am 

 indebted for all my information relative to science), in the 

 " Cornhill Magazine," where he refers to Schcenbein's dis- 

 covery of ozonised oxygen. It will serve by analogy to sup- 

 port my idea of induction as regards the Potato disease. 

 " Scha'nbein had found that atmospheric air, when electrical 

 spaiks are passed through it, acquires new properties, the 

 most noticeable of which consists in a most powerful affinity 

 of its oxygen, to a degree hitherto unknown. In such air a 

 number of bodies, such as silver, upon which oxygen in non- 

 electrised air has no influence whatever, becomes oxidised. 

 Now, the question is. How did Schoz'nbein arrive at the con- 

 clusion that phosphorus slowly burning in the air puts the 

 air into the same state as the electrical spark ? This con- 

 clusion was founded on the observation that electrised air 

 smells like phosphorus, and, vice versa, slowly burning phos- 

 phorus like electrised air. Furthermore, Schombein has dis- 

 covered that the smelling matter possessed the oxidising effects. 

 So the conclusion of the formation and existence of the same 

 thing, the ozone, in two, according to their nature, totally dif- 

 ferent processes, originated in the observation of the same im- 

 pression upon one of the senses, that of smell. If the leader- 

 ship in this combination of ideas had been left to the under- 

 standing, the discovery most probably would not have been 

 made, for the understanding would not have been able to 

 reconcile these two facts— the formation of an agent possessing 

 most powerful oxidising properties, through, or by the side of, 

 a body as highly oxidisableas phosphorus." 



Now, when I wrote to Mr. Gardner to come and see my Po- 

 tatoes growing last season, I said, " Come quickly, as I seem to 

 scent the disease in the air." My sense of smell is most acute ; 

 and in those seasons when crops have been much affected, a 

 fortnight or so before the spotting of the leaves could be seen. 



