The Potato Disease & how to Prevent it

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Preface

I SHOULD have preferred to delay the publication of my notes on the Potato Disease for another year, until additional information could have been obtained on one or two points ; but the losses by the disease last year were so very great, and the attention of the public so generally drawn to it, that on consideration I decided to publish without delay such information as I possessed; and if this little work should meet with a favourable reception on the part of the public, any additional information might be readily embodied in future editions.

THE AUTHOR.

Contents

CHAPTKR PAGE

I. Intkoductort, and first Appearance op the Disease 1

II. Theories which have been advanced to account

Chapter I

Notwithstanding all that has been written on the subject of the potato disease, it appears to me that there is an opening for a work treating of it from a practical point of view, and embodying at the same time our most recent scientific knowledge. There are a great many facts with regard to the disease which I have never seen brought before the public ; and, in the case of other facts which have been brought forward, an entirely wrong interpretation has in some instances been put on them. I also find that a great amount of ignorance prevails generally with regard to the disease ; not only amongst gardeners and labourers, but also to a certain extent in the case of others whose education and experience would lead one to expect differently. '

The potato is certainly not cultivated at present in the way it ought to be, nor has any effort been made to meet the at* tacks of the disease upon well defined principles. I hope the remarks contained in the following chapters will be the means of introducing a better order of tMngs.

Some years ago very great interest was taken in the potato disease generally. Its sudden appearance, and the apparent mystery which attended its arrival, the largo loss of life, and the important economic results that it produced in Ireland, all tended to increase the interest in the subject ;

B and almost anything written, however crude, was published with welcome, and conclusions drawn as to its nature and origin before sufficient data had been obtained to enable one to arrive at anything like a satisfactory conclusion. In fact, the potato disease was in fashion. But now, when ample time has elapsed to enable one to procure sufficient data to arrive at an overwhelming conclusion as to the nature and origin of the disease, nearly all interest appears to have subsided ; and, although our losses by the disease are nearly as great as ever, the potato is abandoned to its fate, and the disease allowed to do its vorst. This is not a desirable state of things. Further effi)rts ought to be made to stop its ravages, and I have been trying some experiments lately with that object in view.

The first thing necessary, is to know what the cause of a disease is, and to get a good knowledge of all the symptoms and facts connected with it ; then you are in a much better position to alleviate the symptoms if you do not effect a cure, and are able to direct your efforts just to those points where they are required.

First Ajppea/rance of the Disease,

The first thing to be ascertained, with regard to the disease, was as to the time when it first made its appearance. I have looked over a great many works on Potato Cultivation previously to 1845, but have not succeeded in finding any allusion to it.

In the article on the Cultivation of the Potato in the * Book, of British Husbandry,' published by the Society for the Diffusion of Useful Knowledge, in alluding to the diseases to which the potato was liable, it says that the principal disease affecting the potato is the curl, &c. Again the Gardener's Chronicle andAgricultv/ral Gazette was the principal paper treating on horticultural and agricultural affairs in 1844 ; and, if anything unusual occurred in the agricultural world, you were pretty sure to see some notice of it. The bound volume for 1844, containing all the numbers for that year, is before me ; but I have searched in vain for one single letter or intimation with regard to the potato disease. That alone is quite sufficient to establish the fact that it was not generally prevalent in that year, and one would be almost disposed to go further and say that it did not exist here, which many believe to have been the true state of the

FIRST APPBABANCEvOF THE DISEASE. 3

case ; but there was one writer who said he noticed it in Kent in 184:4, and it is quite possible that it may have existed to a small extent there in that year. It must be remembered that the weather in 1844 was remarkably fine and dry, which no doubt tended to prevent the spread of the disease; but, supposing this to be the true state of the case, it only prevailed to a small extent, and therefore it will be more convenient to refer to it as the disease of 1845. Some writers thought the disease had been prevalent here for many years, and had been observed by them ; but, on carefully reading their remarks, I agree with the Bev. M. J. Berkeley that they were in error, and that it was the dry rot of Martins, a previous fungoid disease, which they had mistaken for the new disease. Martius's ac« count of this disease is copied in the Appendix.

The Disease in England,

The very first intimation that I have been able to find with regard to anything being amiss with the potato crop in England, is a communication from Dr. Bell Salter of Byde, in the Isle of Wight, which appeared in the Gardener's Chrcmicle of August 16, 1845. The following is an extract from his letter : —

'Potato blight— a blight of unusual character, which almost universally afiects the potatoes in this island — having been the last few days repeatedly brought to my notice by several gardeners, I am induced to lay before the readers of the Chronicle such observations as I have yet been able to make on the subject, being desirous to know whether this plague be in reality, as it is here generally supposed, an entirely new one ; whether it be looal or general in other parts of the kiugdom ; and principally, and lastly, what is the best course to pursue when it has made its appearance. The first appearance is a dark spot on the margin of the leaf, which withers the leaf and spreads rapidly to the stem. The discolouration, soon spreads along the stem in the course of the vessels and the whole plant rapidly becomes black, so that within three days after a plant is attacked it has become totally destroyed. With this appearance in the upper part there coexists a fatal change in the tubers : they become likewise spotted at first near the eyes on the upper sur&ce ; the cuticle separates ; the substance becomes friable ; and the

b2 change soon spreads thronghont the whole potato. These are the leading facts of this destmctive visitation, and I regret that I cannot add any remarks which throw light on the sabject. I may, however, make one or two remarks or soggestions respecting the matter. All situations, whether high or low and whatever the nature of the soil, appear to be equally visited. So universal is the evil that the consequences are likely to be very serious, as in a long journey on horseback I have carefully watched every potato ground as I passed along, and not one could I see uninjured.'

The writer speaks of the blight being of an unusual character, and apparently new ; and his desdription of the disease is so good as to enable us to identify it with certainty. This letter was soon followed by others, as the disease gradually spread over the country ; and the correspondence became larger and larger, and that in the Oa/rdener*8 Chronicle alone, before the end of the year, would be sufficient to fill a large volume, although in the previous year there was no mention of the disease whatever.

Dr. Salterns letter appeared in print on August 16 ; and it is probable he wrote it about a week before it was published ; and, as the disease must have been going on for a little time before it became general, we may say that it began in the Isle of Wight about the middle of July. In the following wee^ (August 23), Dr. Bell Salter sent another letter ; and several other correspondents wrote, one from Jersey, speaking of the disease as general there, although not so bad as in the Isle of Wight, and that it had appeared three weeks before he wrote— -say the end of July. Several other letters were written, from which it appeared that the disease had made a general attack on the south coast of England, early in August ; and one writer fromPlymouth spoke of hundreds of acres having been destroyed in Devon and Cornwall, where it must have begun somewhat earlier. At this early stage, writers began to start theories to account for the presence of the disease, of which the following extracts are specimens : — * We find the potato crop in the neighbourhood of Havant is also affected, but not to so great an extent as your columns describe the injury to have been in the Isle of Wight. On digging up the roots, the tubers nearest the surface of the ground are in general the only ones affected, though in some plants the injury ex-

DISEASE IN ENGLAND. 5

tends throughout the potatoes belonging to that root ; but where it does not so extend the rest of the tubers appear perfectly well grown and healthy. It certainly is not a disease of the root, bat appears to be the consequence of an injory done to the haulm and leaf. Is not the cause to be attributed to the severe winds and white frosts experienced a short time ago injuring all above the ground, and preventing the vessels of the plant from drawing up the juices from the roots, and these tubers full of stagnated fluid immediately decay ? Supposing this to be correct, I have practised the cutting off the haulm, with a reaping hook, about an inch below the earth, into where the frosts and winds might be supposed not to have injured the vessels of the plants, hoping, by these means, to induce them to bleed, and thereby relieve the tubers of their stagnated fluids, &c.' Another writer says : — * I believe those persons are perfectly correct who ascribe the potato disease to an excess of moisture to the plant, consequent on the late continued rain and absence of sunlight, and that it has been greatly aggravated by a too retentive soil. Our garden is so thoroughly drained that, in most summers, we suffer excessively from drought ; and, though the haulm of the potatoes grown in it is more or less affected, the tubers themselves are comparatively uninjured; while in a piece of ground, apart &om the garden, having a stiff clayey subsoil, the disease has been much more violent. I am inclined to connect the disease with the sudden heat of the end of June and beginning of July, as in a piece of Dutch potatoes which was not planted before that time scarcely a symptom of disease is perceptible.' These are fair specimens of the ideas of some of the earlier writers on the subject. I could put in a great many more, but they might not be interesting to the reader.

The disease from this period gradually extended northward, and about the middle of August was. noticed in the counties of Gloucester, Wilts, and Oxford* The Eev. M. J. Berkeley wrote to the Oardener*s Ohronicle about this time, stating that the disease had not then appeared in Northamptonshire ; but the following week he wroter to say that it had made its appearance. A little before this ihe disease had appeared in Cambridgeshire/ Bedfordshire, -Hertfordshire, and Buckinghamshire. About this time the <^bease appeared at Netherby, in Cumberland, in an isolated case,

THE POTATO BISBASB.

whilst ihe potatoes in the surronnding fields were unaffected. I attribute this case not to the disease having spread to Cumberland all the way from the south coast ; but believe, for reasons which will be afterwards given, that there was another centre of attack in the neighbourhood of liverpooL By the end of September the disease, or * murrain,' as it Was called, had been observed in Yorkshire and other northern counties. The disease, in fact, gradually spread ; and it will suffice to say that, although some parts of Wales appear to have escaped without much loss, and that in some of the northern counties it did not prevail so extensively, there does not appear to have been a single county in England that entirely escaped its ravages.

The Disease in Bcotland, The disease did not appear in Scotland so soon as in England. Until the end of September it did not seem to

Abstract of the State of the Potato Crop in Seotlandy drawn up from the Retwme to the Home Officet November 18, 1845.

Synods of

Lothian and Tweeddale

Merse and Teviotdale .

PnmfrieB • •

Gallowaj . • •

Glasgow and Ayr

Argylo

Perth and Stirling

Fife ....

Angofi and Meams

Aberdeen • « •

Moray • • .

Boss^

Sutherland and Caithness

Glenelg

Orkney

Shetland • •

49 61 46 29 94 21 40 44 8

24 7 3 3 7 7

8 5

26 88 46 21 22 16 2

3 Pt

«6

8 16 it v9f

DISEASE IN SCOTLAND. 7

ha^e been mnch observed ; bat later in the season it became CQore prevalent, and from the reports in a return to the Home Office, November 18, 1845, the disease was reported as very bad in many places, and there were traces of it in almost every connty. The Shetland Isles and Orkney appeared almost the only places which were exempt. The object of the return waa to ascertain if the potatoes were sound in Scotland, so that tubers could be obtained from that country free from disease. The return was unfavourable, except as before mentioned; but, supposing it had been otherwise, the sound potatoes would not have been of much service when brought into contact with others ; but this fact was not known then. (See table on opposite page.)

From this return it appears that the disease had caused a loss of a quarter of the crop or more in the Synods of Lothian and Tweeddale, Merse and Teviotdale, Dumfries, Galloway, Glasgow and Ayr, Argyle, Perth and Stirling, and Fife ; and less than a quarter of the crop in Angus and Mearns, Glenelg, and Aberdeen ; whilst in Moray, Boss, Sutherland and Caithness, Orkney, and Shetland it had not been then observed.

The Disease in Ireland.

On September 8 the disease was observed at Eansale and Dublin. The Oa/rdener's Ohronicle said, on October 18, 1845: — * In Ireland matters seem to be worse. Although the statements which we found it our duty to make were lately declared to be exaggerations, and the existence of the murrain in Ireland was altogether denied, or asserted to be trifling and quite local, yet it now appears from the Irish papers to be raging in that country, and the most formidable consequences are anticipated.' The Oork Examiner was even of opinion that the Irish potato crop was then so much diseased that the Government was imperatively called on to throw open the ports without delay for the free admission of foreign corn.

Mr. Dillon Oroker, in a letter to the OonstitvMon^ drew the following picture of the crop in the county of Cork : — * I came to Lord Kingstown's yesterday, and grieve to say I found all in this part of the country labouring under the delusion that the pestilence had not reached them, and that all the potatoes were sound ; but, alas ! in a drive of eleven Irish miles, I found every field more or less affected. I stopped on the road wherever I saw a &rmer digging potatoes. I asked if the crop were soiind ; immediately was I answered, " Perfectly so ;" but, on going into the field, I had little difl&culty in speedily convincing each that it was not so.'

The Limerick Ohronicle said that in the connty of Limerick the fields showed unequivocal symptoms of the rot.

The Belfast Ohronicle said that the crop was as defective as report had represented, and that it could not be denied that the rot in that part was general.

The Belfast Protesta/nt Jowmal said that the accounts from the towns round Belfisist were discouraging, and that there was no doubt that in the counties of Down and Antrim the disease had spread to a serious extent*

By the end of the year the disease had spread over the greater part of Ireland, Gal way and other parts on the west coast being the least affected. In October affairs assumed such a serious aspect, that Sir Robert Peel appointed Dr. Playfair and two other gentlemen as commissioners to go to Ireland and inquire into the subject. These gentlemen made every possible inquiry, and published altogether three reports on the disease. The first two touch on matters that are not of much interest to us now ; but an extract from the last, 'which is the most important, is published in the Appendix.

The disease in Ireland assumed a much more serious aspect than in the other parts of the kingdom, on account of the fact of such a large number of people subsisting almost entirely on the potato. It was estimated that 4,500,000 persons lived on potatoes alone for eight months of the year, and that they consumed, on an average, 10 lbs. per diem ; so that 45,000,000 lbs. per diem were required.

The average quantity of potatoes obtained from an acre of land in England used to be estimated at eight tons, or, allowing one ton for seed, at seven tons net. That being the case, the conclusion was arrived at that the potato crop of Ireland, for the mere consumption of those who fed upon it exclusively, amounted to the immense quantity of 10,800,000,000 lbs., and required for its production 688,647 English acres of land. But to this it was necessary to add the potato diet of 3,500,000 persons who only fed upon potatoes in part. If their consumption was taken at 1 lb. per head per diem for the whole year, and it was also assumed that during the four

DISEASE IN IRELAND. 9

months, previously excepted, 1 lb. per head per diem was also required for the rest of the population, already * taken at 4,500,000, we should find the whole consumption of potatoes in Ireland to amount to 12,617,600,000 lbs. per annum, for producing which 804,687 English acres must have been under potato cultivation.

Im ordinary tillage one ton of potatoes was required per acre for seed.* Therefore, merely to plant as much land as seemed necessary to feed the Irish population would have consumed above 800,000 tons, and required 100,000 acres of land in addition.

But as Ireland was an exporting country, sending her potatoes elsewhere in large quantities, it may not be too much to assume that the number of statute acres under cropping with this class was a million, or about one- fourteenth of the whole cultivated land.

Now, when the disease appeared in this country, although prevalent over a considerable part of it, it was not till the following year that its attacks were fully developed ; and the results were disastrous, culminating in the Irish famine, with a loss of thousands of lives ; and the English Government had to contribute 8,000,000?. for the support of the people. Besides this, the disease brought about sundry political changes. The growth of the potato was, in a measure, discontinued, and a large number of people emigrated to the United States of America ; and, in a few years, the population was reduced by at the least three millions ! Now, these important facts ought to be borne in mind, and have their due weight assigned to them, in considering the time when the disease first appeared in the country. It certainly does not seem at all probable that such tremendous consequences should have been suddenly produced in this country by a disease which had been prevalent for many years ; neither do I think such was the case.

* A greater weight than is usually planted now.

Chapter II. I

Theories which have been advanced to account for the Origin of the Disease,

The potato is believed to have been introdaced isfc> ihe United Kingdom from Virginia by Sir WaU»r Saileigli, about the beginning of the seventeenth Goa^aarj, and vras coltivated on his estate in J^kad aad in other parts of that conntry in •mwaaS&^mvj for many years, and abont 1694 was introdaced into Lancashire, where its cultivation soon became general, and gradually spread over the other counties of England ; and if we allow several more years from 1694 for this to have taken place, say until 1745, the potato must have been in general cultivation for at least a hundred years previously to 18^5. For many generations the potato was thus cultivated year after year as before mentioned, and no sign of the disease exhibited ; when, all on a sudden, it appeared, and spread rapidly over a wide range of country. What was the cause of the malady, and why did it not appear before 1845 ? This was the most important question of the day, which set everybody speculating as to its origin. From the very first appearance of the disease, and before scarcely any of the facts were known, every writer had a theory of his own. Several attributed it to the cold, wet season of 1845 ; others to the excess of electricity iu the atmosphere, or the exhausted vitality of the tubers ; and others to bad cultivation, frost, and even snails or worms. A German gentleman wrote a pamphlet attributing it to the absence of magnesia in the soil, and several pamphlets were written attributing it to the use of guano and other stimulating manures. Mr. Al&ed Smee started the theory that the leaf of the potato was first punctured by an insect, a kind of aphis, and then the plant was attacked by the disease. He published a book on the subject dedicated to Prince Albert ; and, 1 believe, retained that theory until the day of his death, which occurred not long since. I propose now to bring forward and review some of these theories ; and if I were not afraid of tiring the patience of the reader, I would bring forward and review

THEORIES ADVANCED. 11

every theory that has been advanced ; but perhaps that is unnecessary, although at the same time I do not think I have left any out that are worth consideration.

Several writers have been disposed to attribute the origin of the disease to the electrical state of the atmosphere or an excess of electriciiy in the atmosphere/ because they had observed the first appearance of the disease in potatoes soon after damp, sultry weather, particularly if followed by imin ; and although this theory has been combated, and is not general^ entertained, there are people who are still disposed to cling to it — amongst whom is the Rev. R. Fenn, the Rector of Woodstock, who has been very successful in raising new seedling potatoes. He sent a communication on this subject to the * Horticultural Journal,' 1872, vol. ii. — an extract from which I think will be found interesting, and produce it here, although I cannot agree with his conclusions. Mr. Fenn says : —

I stand firmly hy my old colours — an electrical state of the atmosphere in connection with rain heing a chief and first cause in hringing ahout the potato disease. In the middle of July my new seedling potatoes induced me to go and stay for a few days in the neighhourhood of Bedfont^ to watch their precocity and other particulars. Not a drop of rain had fallen on them for some weeks^ and my supervisor was praying for some to come down. I did not sympathise with him, and my note-hook ran thus : — ' July 10 : Atmosphere hecoming very foul and thickening ; I douht the potato disease is coming sooner than usual this year.' In hjot, 1 hinted at the advisahility of getting them all up, as most of the sorts were already very nearly ripe ; but we had named the day when friends and critics were to meet to admire or pass condemnation on them ; so they were left to their fate and the elements, and I secretly hugged the hope that the already hrewing tempests might pass over without rain, for then I knew my seedlings would remain without spot ; or, otherwise, that the rain would come without the thunder and lightning, and then they would he equally safe. Well| on the 18th, the surcharged clouds could stand it no longer, and on the 19th storms passed over the neighhourhood. But I was forearmed for what I intended to do ; so on that very evening, I worked tiU darky taking up every other root of my choicest proved seedlings from the ridges, and so on for two or three days, both in storm and sunshine, till I had secured as many as I wanted of my precious ones. Many of them have since appeared in the Council Chamber at South Kensington ; and it was lucky for me that my experience in the ways of atmospheric causes led me to make no delay, as those of their fellows, which I allowed to remain in the soil, with the hope of a chance of being afterwards able to show them off in their growiofir state to my friends, &c., were almost destroyed by the disease, whilst not a single tuber is lost or touched by it of those which I lifted before they became scarcely blotched in the haulm.

Again, as regards my newest seedlings, which I raised from the seed apples, under glass last year, one-third of them I planted daring the first quarter of last April, in the open garden, and one-third of them, from want of room, at Bedfont. In the beginning of July I l>egan to have my suspicions about the disease, so I planted the remaining third pcurt in any spare comer of the garden. Now, I beg of you to judge, by the result of these precautions, whether the disease is so profound a mystery as some people will have it to be. Of the April planted lo^ which were all of them, as a matter of course, left to acquire their full growth and features, not two dozen tubers survived the murrain. Those sent to Bedfont were somewhat more lucky ; but of those which I planted in July, the very smallest of the fry, anyhow and anywhere, and ^hich began growing after the atmosphere had become cleared of its electricity, I finished lifting them in the third week of October, a most perfect lot, and surely they have been saturated enough and to spare with mere wet. So if merely plain rain, unaccompanied with tempest, will bring the disease, why is it that this last, and late planted third, was left scathless ? [This will be answered.] I am most thankful to say that they were ] and as the above will serve to show, by simply guarding myself against that state of the atmosphere, which is sure to arrive sooner or later during July and August, I have saved my credit and as many as I chose of my crops, plus the results of years of experimental crossings for the future.

I will now say a few words with regard to the electrical theory. All electrical phenomena, inolnding thunderstorms, are subject to certain fixed laws, which never vary. All thunderstorms are produced by one of the following canses : — Either, first, by the passage of electrical finid from one cloud to another ; or, secondly, from the earth to the clonds ; or, thirdly, from the olonds to the earth. This takes place, how« ever, only nnder the following circumstances : — The cloud or part of the earth from which it passes must be in a positive state of electricity, and the clond or part of the earth to which it does pass in a negative state of electricity; the exchange goes on until both are in the same condition. Another important law is that it moves by conduction — i.e. as some substances, such as metals, water, &c., are conductors, it will pass along them ; but glass, fur, atmospheric air, &c.,