Sepienilier 12, 1872. j 



JOURNAL OP HORTICULTUEE AND COTTAGE GARDENER. 



209 



light, free from frost till planting time, and am very 'careful 

 not to injure their first and best shoots. A few days before 

 planting I go to the trouble of delving-ont with a penknife 

 every shoot except one, the first and best. One shoot is quite 

 sufficient to leave on a moderate-sized tuber, with careful 

 planting in order not to rub it off, and where this twilight- 

 single-layering plan is at once adopted, it signifies nothing 

 whether a Potato-set is greened by the sun in the open air or 

 no. It becomes sufficiently greened and toughened when 

 spread out in moderate light, in preparation for seed. My 

 piride has got a sufficient fall this year never to allow my seed 

 Potatoes to be destroyed in future. 



Very rich people might cover an acre of ground or so with a 

 .glass structure, and grow Potatoes under it, giving plenty 

 of ventilation and artificial watering. This, I consider, is 

 the only way to set the disease at defiance, with the glass as 

 a nonconductor and repellant of the fungoid rain during 

 thundery, hot, muggy weather. I grew my newest crosses 

 from seed under glass last season, and not a symptom of disease 

 appeared on them. I shall lose two-thirds of them this year 

 from disease in the open ground. What do you think of that ? 

 The best strains of the best sorts studied and combined for 

 flavour, form, and appearance, years of trials dashed away just 

 at the close of a lifetime! Still I hope for consolation, for out 

 of about a thousand seedlings I may fairly calculate on some 

 three hundred sorts of my pretty ones being left — enough you 

 may possibly think for any man with a conscience. — Upwards 

 .and Onwards. 



We are of opinion that the outcry proclaiming the extensive 

 jjrevalence of this scourge is vastly exaggerated. We know 

 from personal inspection that the Potato disease is not preva- 

 lent in the Isle of Man, where it is the principal crop, and 

 from whence thousands of tons are annually exported. We 

 also hear that in Ireland the disease is not excessively de- 

 veloped. The Irish Farmers' Gazette, one of the most ably con- 

 ducted journals of that island says, " So far as Ireland is con- 

 cerned, it would be folly to deny that the state of the Potato 

 •crop is far from being satisfactory. Disease exists in a large 

 number of districts, and owing to the unfavourable weather for 

 planting last spring, until a considerable part of the season had 

 jiassed, the tubers in many parts of the country are small and 

 immature, so that, as a County Kilkenny farmer expressed it, 

 a large extent of ground has to be ' stript ' before a sufficient 

 ■quantity of fair-sized tubers can be obtained to send to market. 

 With all this, there is nothing like a panic in Ireland, nor is 

 -there the slightest dread that ' a second Irish famine ' is about 

 to occur, asaLondon daily, noted for its sensational proclivities, 

 recently asserted." 



Much do we marvel to see any man of intelligence affirm 

 -that lightning accompanied by storms in early autumn 

 -occasions the disease. The wet accompanying the high tempe- 

 ratures of that season may promote the progress of the putre- 

 faction of the tubers, but the disease was in them before the 

 -occurrence of these storms. 



Twenty-five years since the writer of this published as follows : 

 — This disease was most extensively destructive of the tubers of 

 the Potato crop in the British Islands in 1S45 and 1846. But 

 dt is not a new disease to the vegetable nosologist, nor confined 

 to these Islands. 



In July, August, or early in September, whilst the fibres 

 ■connecting the tubers with the stem are still full of sap and 

 the vital circulation is still in force, this disease makes its ap- 

 pearance. The leaves and stems become blotched with black 

 decayed parts : the putrefaction or ulceration is moist, and, if 

 the weather be wet and ungenial, proceeds so rapidly, that an 

 unpleasant effluvium is very perceptibly evolved. The stems 

 ■ulcerating and decaying whilst the fibres connecting the tubers 

 with them are still vigorous, the infectious ichor is communi- 

 cated with the sap, and, passing into the still immature and 

 juicy tubers, imparts to them the gangrene. The infection is 

 first apparent at the end nearest the connecting fibre, spreads 

 gradually throughout the liber of the tuber, rendering it brown 

 like a decayed Apple, and lastly, causing the putrefaction of 

 the whole interior. Previously to this final decay the increased 

 specific gravity of the tuber is very remarkable, amounting to 

 about one-third more than when the Potato is healthy. When 

 boiled the infected portions become black ; but when sub- 

 mitted to a dry heat of about 200° they rapidly part with 

 moisture, and the progress of the ulceration is checked, if not 

 •entirely stopped. 



When the disease makes its appearance before the stems and 



foliage are dead, it has been judiciously recommended by Dr. 

 Lindley that these should be pulled up. This, of course, pre- 

 vents the communication of infected sap to the tubers. Cut- 

 ting off the stems has been found ineffectual, apparently 

 because some of the stem then remains to impart the sap. 

 Messrs. Dillistone, of Stunner Nursery, Suffolk, say, "We 

 tried the plan of p ullin g up the haulm immediately upon per- 

 ceiving the disease this year on the early varieties — viz., 

 Shaws, Ash-leaved Eidney, &c, and the result is all that could 

 be desired. We have lost scarcely any. The tops were left on 

 the ends of some rows of Shaws for the sake of experiment, 

 but nearly all the Potatoes spoiled. Mowing off the tops we 

 find to be useless." 



It has been suggested that either fungi or insects are the 

 cause of the disease ; but I think both these are excluded by 

 the fact that it appears in every quarter and latitude of the 

 globe — in the frigid climate of North America, in the temperate 

 locality of Devonshire, and between the tropics at St. Helena. 

 Now, I know of no fungus or insect that has its habitat alike 

 uninfluenced by heat or cold; and even less conceivable is it 

 that a fungus or insect is just created for the purpose of de- 

 stroying the Potato crop. The fungus or insect, it is more 

 rational to conclude, must have existed throughout time, and 

 its ravages have only been felt by increasing degrees, as the 

 Potato has gradually reached a state of disease fitted for the 

 nutriment of the parasite. The same and other facts preclude 

 unfavourable seasons from being the cause of the disease, 

 though they may hasten its progress. The disease was quite 

 as prevalent in 1846 as in 1845, yet no two years could have 

 had seasons more different. It is quite clear that no local 

 cause — such as the employment of any particular manure, the 

 staple of the soil, or the mode of culture — can be the origin of 

 the disease, for the crop has been grown on all possible 

 varieties of arable soil, with and without manures, and in 

 various modes ; the sets have been dug-in and dibbled-in ; the 

 plants have been earthed-up and left unearthed ; yet in all and 

 in each has the disease appeared. The cause, then, must be 

 one of universal applicability, for the disease is epidemic in 

 the widest sense of the term. Does it arise from the vital 

 powers of the varieties being exhausted ? No ; for, in many 

 instances, the most recently raised from seed are as productive 

 of diseased tubers as the oldest cultivated kinds. Does it 

 arise from the almost universal practice of taking up the 

 tubers as soon as the stems are dying or dead, and keeping 

 those tubers out of the soil for four, five, or more months ? 

 I am of opinion that this is the cause. The practice is nearly 

 universal : it is the practice throughout Europe, as it is in 

 America, St. Helena, and the hill districts of Hmdostan ; and 

 in all those regions the disease prevails. It is not the practice 

 in New Zealand, and there the disease is unknown. 



Now, has the withdrawal of bulbs and tubers from the soil 

 the effect of gradually rendering them and their progeny 

 diseased ? I think no horticulturist or vegetable physiologist 

 will answer in the negative. A writer in the Gardeners' Chro- 

 nicle of the year 1846 (p. 478) , most correctly observes that 

 the bulbs of Hyacinths, Tulips, and Crocuses keep well in the 

 ground, but if taken up have a strong tendency to decay. 

 But what effect has this treatment upon the plants to which 

 they give birth ? Why, it imparts to them disease. The 

 strain, the beauteous variegation of the Tulip's petals, are the 

 effects of disease. Leave the bulb in the soil throughout the 

 year and it returns to its natural vigour and simple colours. 

 No variety occasioned and preserved by such artificial treat- 

 ment will endure beyond a few years. It is no effectual objec- 

 tion that seedling Potatoes are now affected with the same 

 disease, for such diseases are hereditary in vegetables as well 

 as in animals, and the seedling's tubers have been subjected 

 to the same keeping out of the soil for months as were its 

 parents. Neither is it an effectual objection to say that only 

 of late years the disease has prevailed, for it has been noticed 

 for full fifteen years, and it is only by such detention from the 

 soil through a series of years that the disease is advanced to 

 its prevailing malignant form. It is only thus that varieties 

 of the Tulip and Dahlia are gradually destroyed.* 



Tubers and bulbs kept out of the soil, whether freely ex- 

 posed or in covered heaps, all undergo the same chemical 

 changes — absorbing oxygen and emitting carbonic acid, and 



* It is no new disease — no modern introduction into the lists of vegetable 

 nosology. I have noticed it for the last fifteen years. From 1S30 to 1841 it 

 seriously iojured the Potato crops of Germany, and is noticed by Von 

 Martius as the Potato gangrene. — Von Martius " On the Epidemics of Pota- 

 toes." 



