t\ I 7- TO + Issued March 7, MO. U.S. DEPARTMENT OF AGRICULTURE, ftUREAU OF PLAJST INDUSTRY (uvula, Xo. 52. H. r. 1. allow ay, 1 hi. r of Bureau. WART DISEASE OF THE POTATO \ pANGEROUS EUROPEAN DISEASE LIABLE TO UK INTRODUCED INTO THE UNITED STATES. W. A. ORTON, Pathologist, ETHEL ('. FIELD, 9< u.vmic Assistant, Cotto* wi> Truck Diseases and Sugar-Plant Investigations. •jiiit.;— 10 WMMINO- M ~~| i BUREAU OF PLANT INDUSTRY. Chief oj Bureau, Beverly T.Galloway. Assistant Chief of Bureau, G. Hakold Powell. Editor, .1. E. Rockwell. ' lii: / Clerk, James E. Jones. [Cir. 52] 2 H I [.— 560. WART DISEASE OF THE POTATO; A DANGEROUS EUROPEAN DISEASE LIABLE TO BE INTRO- DUCED INTO Till-: UNITED STATES. INTRODUCTION. A new disease of the potato which has been exciting alarm in Europe i- likely to in' introduced into this counl ry at any time 'This circular is issued t<> call the attention of American growers and importers of potatoes to this danger and to urge their cooperation in an effort to prevent it from securing a foothold here. It is important that any cases discovered he promptly reported and all possible means taken to prevent its occurrence. DESCRIPTION OF THE DISEASE. The disease, which has been known as '"warty disease," "black scab," "canker." and "cauliflower," is one which attacks the tuber principally, and consequently is not observed until harvesting time. In a bad attack of the disease big, dark, warty excrescences, sometimes as large as the tuber itself , appear on its sides or ends. "Thegrowth consists here of a ma-- of coral-like or more or less scabby excres- cences or nodules, similar in appearance to the well-known crown or io.it gall of apple-. The adherent earth can he easily washed oil' when the character of thegrowth becomes more apparent. It is not spongy and not detachable from i he tuber. It i- of a somewhat lighter color at the base and dotted with minute rusty-brown spots over the surface. In an advanced stage the tubers arc wholly cov- ered by this growth, ha\ ing lost every resemblance to potatoes. The\ are lumps of irregular outline, never spherical or oblong, hut simply a mass of ragged and edged excrescences. A -till more advanced stage occurs when the fungus ha- utilized every particle of food stored in the tuber and has reduced it to a brownish-black soft mass giving off a very unpleasant putrefactive odor. Tin- is the most dangerous stage of the disease, and the tubers which have reached it can not be harvested whole. They break in piece-, ami thus the hrow n ish, pulpy ma--, consisting almost entirely of spores of the fungus lClr.52] 4 WART DISEASE <>F THE POTATO. and remains of the cell walls of the potato, is broken up, the spores are liberated in millions, and the land is badly infected for years." (Giissow, L909.) (See Pis. I and II.) In a mild attack the eyes first appear grayish, then turn brown, and finally black, while in a healthy tuber these are whitish or purplish in color. The tuber is only slightly disfigured and its keeping qualities do not seem to be impaired. While the tuber is the part of the plant chiefly affected, infection may take place in all the } T oung tissues of the plant, the roots, stolons, stems, and even the leaves. THREATENING NATURE OF THE DISEASE. All reports indicate that the potato wart is one of the most serious of all known diseases of the potato. It converts the tuber into an ugly, irregular, and utterly unsalable growth. When established in a field it may affect the entire crop, and the land remains so Infected that potatoes can not be successfully grown for six or more years. We quote from writers abroad the following: J. W. Eastham (Yearbook, College of Agriculture and Horticulture, Holmes Chapel, lDO-i-): "When once established in the land it is use- less to grow potatoes again until the pest has been starved out or otherwise destroyed; but so far as is known no other crops are liable to be attacked. Quite the worst case seen in Cheshire occurred on land that had not borne potatoes for six years; 'seed' from the same source as that employed on this land yielded satisfactory results else- where, indicating that spores were not introduced by the seed, whilst the manure employed started no infection elsewhere. This indicates prolonged vitality on the part of the fungus, which would render starving out a very tedious process." E. S. Salmon (Gardeners' Chronicle, litdT): '"It is quite clear, however, that the 'black scab' disease threatens to inflict such serious injury on the potato crop as to warrant the Board of Agriculture taking official action. * * * The disease is viewed with alarm by both the scientific and the practical man, and yet no steps arc being taken to deal with this pest which, if it is allowed to spread through the country and to reach Ireland, will cause losses of hundreds of thousands of pounds." Borthwick (1!K)7), retelling to an outbreak in Scotland, says: "The whole crop was damaged to the extent that they could not be used. They were quite useless, the early varieties being, if anything, worse than the late, especially the early kidneys. The disease was first noticed when the new potatoes began to form. It first appeared on the stems as a greenish looking canker, which attacked the tubers as they grew and soon made them a mass of corruption." [Cir. 52] C» 52, Bureau oil' Plate I. Potato Plant Attacked by Wart Disease. iAfter GussowJ Digitized by the Internet Archive in 2013 http://archive.org/details/wartpotOOunit w \i;t DISEASE OF THE POTA m. , r ) M. C. Potter (Gardening, L908): " From ;ill accounts the disease is spreading rapidly in the infested area- and the amount of damage is yearly increasing. * In certain allotments * * * it lias been found impossible to grow potatoes." John Percival (1909): "Potato warl has already become a serious trouble in many districts in this country, ami it is likely to develop into the worsl pest with which the grower will have to deal unless vigorous measures are adopted to stamp it out." T. Johnson (1909): '" It need- only a very casual acquaintance with the fact- of the case in the British I-les from the time of the discotery of the trouble by Potter in 1!"^ to the present time to warn one of the necessity of taking all possible steps to stamp out a disease which may become as serious as ordinary leaf-blight and less amenable to treatment. it i- now found in many districts in England, Wale-, and Scotland. It is often mi pronounced as to destroy the whole crop, and it is not confined to garden plots. Warty tubers are naturally poorer in food matter than healthy ones, and when not destroyed in the held do not keep well in store. They oughl to be destroyed as Boon as found, and on no account saved for seed." The Gardeners' Chronicle, 1908: "This disease * * * is excit- ing -ome alarm in Germany, where it is said to be spreading. It appeal- to have been recognized as of local occurrence for some time in the neighborhood of Diisseldorf, Elberfeld. During this season it ha- proved so injurious a- to have ent irely dest roved the crop in many gardens where potatoes have been raised year by year." I )r. (). Appel (1908), on the other hand, says: "According to reports of Spieckermann, Schneider, and Josting, who have observed it this year in Germany, the disease is not of economic importance." The British Board of Agriculture and Fisheries made it a notifiable disease in L907 under the Destructive Insects and Pests Acts. L877- 1907. The following report (Gardeners' Chronicle, L909) was made: "The board of agriculture and fisheries de-ire to notify that 2+4 cases of wart disease or black scab in this year"- potato crop had been reported to them up to October '■'>. These cases have occurred in the following counties: Shropshire, 60; Staffordshire, 57: Lancashire, 50; Cheshire, 30; Warwickshire, 25; Worcestershire and Leicestershire, I each; Derbyshire, 3; Merioneth. 2; and I each in Perthshire, Stirling- shire, Dumfrieshire, Cumberland, Nottingham, Berkshire, Flintshire, Brecanshire, and Glamorgan. A few case- among field crops h ; i\ e been found in the counties in which the disease i- most common, but in the great majority of cases the disease has occurred on allotment- or in gardens in which potatoes are constantly grown * * *. The dis- ease has been known in certain districts for ten to fifteen years, and a- growers ha\ e taken no steps to che.k its progress, it is now causing 52] b WART DISEASE OF THE POTATO. serious loss * * *. All cases of wart disease must be notiQed to the secretary, board of agriculture and fisheries * * *. In the case of farmers who sell 'seed' potatoes, notification of the disease is of especial importance, and failure to notify must be regarded as a serious offense * * *. Persons concealing wart disease are liable to prosecution and a penalty of £10." PRESENT DISTRIBUTION OF THE DISEASE. The disease has been reported from England (see p. 5), from Scot- land in Perth, Sterling', and Clackmannan counties; from Ireland in Down County; from Wales; from German}- in Westphalia and the Rhine provinces; and from upper Hungary. It has not yet been brought to the United States so far as known, but has already crossed the Atlantic and become prevalent in Newfoundland, where it was lately discovered b} 7 Dr. H. T. Giissow, Dominion botanist, who pre- sented a very interesting paper on the subject in December, L909, before the American Phyto pathological Society. Knowing the serious character of the new pest from personal observation of the losses caused in England, he promptly issued a warning bulletin. The Canadian government proposes taking active measures to prevent the further introduction of the disease. Doctor Giissow stated that there have been recent importations of seed potatoes from Newfoundland into the United States. NATURE OF THE PARASITE. The organism causing the disease is a fungus discovered in 1890 in potatoes from upper Hungary by Schilbersky, who named it Chrysqphlyctis enddbiotica and placed it in the lowest group of the Chytridiacea?, Olpidiacese. By others the fungus has been supposed to be Oedmnyces leproides. We quote from the excellent description of Prof. T. Johnson, as follows: "The vegetative form consists of a naked mass of protoplasm which may be distinguished in the host cells (just below the epidermis) by being denser, homogeneous, and finely granular. It may be seen abutting on the host protoplasm, and disputing with it, as it devours it, occupation of the enlarging cell cavity. The protoplasm follows and then the cell wall. This, though brown, does not, like the protoplasm and nucleus, disappear. The starch grains art 1 the last attacked and remain white and unin- jured for some time in an invaded cell. The parasitic plasmodium passes from cell to cell by boring its passage through the host cell wall * * *. It is in this stage that it stimulates to active cell division the surrounding host cells and produces the gall or wait." [Cir, 52] ; Plate II Resting Spores of Wart Disease. Section through n small tubercle showing sporangia. (After Giissow.) Tuber Showing Warty Excrescences. Prom Joiirnnl i il I culture, Jnntmi W.\i;i DISE \-r OF l ill POTA DO. 7 Daring the summer the plasmodium rounds up, forming a smooth, yel- lowish wall about itself. Later the contents of these zoosporangia break up into numerous zoospores, which escape through ;i hole in the wall and attack healthj potato tissue. "As tlir tuber ripen-, the parasite replaces the summer sporangia l>v resting ones, which carry the disease through the winter and serve to propagate it in the spring *. The resting sporangia, .'in 7<> " in diameter, are very numerous in diseased tubers and are easily recognizable with a pocket lens. Under the micro-cope the wall is seen to be not smooth, but ridged or angular. These brown ridges or hands form pari of a kind of epispore which arises as the sporangium ripens, and seems to be formed from the residual con tent- of the host Cell when not also from its cell wall as well * * *. The epispore is thus deposited from without as a third layer on the thickening wall of the sporangium. If this more or less artificial epispore is ignored, then one may speak of the spore wall as smooth * * *. As a rule there is only one resting sporangium in a host cell; occasionally there are two." It is exceedingly difficult to germinate these resting -pore- artificially. Professor Johnson suc- ceeded in bringing about germination by placing them in potato juice. lie write-: "At last the potato juice, exercising possibly a chemo tactic influence, gave success; and sporangia with split walls and escaping zoospores were found. These showed the same sluggish movements observed in the sporangia of certain other Chytridians disturbed during their resting period. Each sporangium contains hundred- of more or less pear-shaped uniciliate /oospores. The zoo- spores measure from L.5 to --'.I i* in diameter. The body is actively amoeboid, while the cilium is comparatively passive." (T. Johnson, 1909.) Infect ion takes place usually at the " eyes " of the tuber through t he zoospores of either the summer or resting sporangia which are found infesting the surrounding soil. It is also believed by Johnson and other- thai infection may take place through the internal passage of plasmodia from diseased seed passing through the stolons arising t here- from, and so into the newly formed tubers. MEANS OF EXCLUSION. At the present time the United State- has no legislation that will prevent the importation of such a trouble. No quarantine is main- tained against plant diseases, nor is the Secretary of Agriculture authorized to inspect or reject infected potatoes, seeds, or nur-er\ -lock of an\ description. [Cir. .-.--'I 8 WART DISEASE OF THE POTATO. The most effective protection against the importation of potatoes is the tariff of 25 cents a bushel. Yet in spite of this the following quantities have come to our markets from abroad: Country from which imported. Bushels. Austria-Hungary 34,909 Belgium 37,275 Bermuda 68, 964 Canada 421,106 Germany 152, 323 Netherlands 9, 316 Spain 1,774 United Kingdom : 1,192,074 Other countries 30, 419 Year ended .Tune 30— 1900. Quantity. Total 1, 948, 100 Value. Dollars. 17,146 14, 422 95, 205 126, 798 69, 761 5, 379 1,558 504,377 18,417 853, 063 1907. Quantity. Bushels. 741 75 87,048 11,393 39, 419 5,704 7. 730 5,673 19, 134 176,917 Value. l>n liars. 331 84 135, 669 5,970 19,984 2,184 7,408 3,706 17, 399 192, 035 1908. Quantity. Bushels. 1, 723 6,889 80,711 177,102 62, 059 38, 892 11,246 2,269 23, 061 403,952 Value. Dollars. 740 3,650 109,561 80,000 38,308 18, 109 11,590 1,321 19,015 •283,032 The principal ports of entry of potatoes in 1908 were as follows: Aroostook, Me., 67,766 bushels; Bangor. Me., 56,312 bushels; Boston and Charlestown, Mass., 34,901 bushels; New York, 202,069 bushels; Passamaquoddy, Me., 3,286 bushels; Porto Rico, 19,285 bushels; Key West, Fla., 2,613 bushels; Arizona, 8,213 bushels; Champlain, N. Y., 1,390 bushels; other ports, 8,057 bushels. Total. 103,952 bushels. 6 Since the interest and knowledge of the public must be our main dependence in preventing the establishment of the potato wart in America, it is urged that all importers, dealers, and consumers of foreign potatoes watch for the disease and promptly report to the Department of Agriculture at Washington any cases discovered. All infected potatoes should be boiled or burned. No part of any lot containing diseased potatoes should be used for seed purposes. If the disease is found on growing potatoes, heroic measures should be taken to eradicate the trouble by burning the entire lot and planting no more potatoes on that field for six or seven years. There should be some modification of our laws so as to enable the Secretary of Agriculture to deal promptly with special dangers of this sort arising from the importation of infected plants. "Bulletin 7(5, Bureau of Statistics, U. S. Dept. of Agriculture, p. 54. '' Information furnished by Bureau of Statistics, U. S. Dept. of Agriculture. [Cir. 52] LITERATURE. 18!>t>. Schilbersky. Kill neuer Shorfparasit der Kartoffelknollen. Berichte tier Deutschen Botanischen Geeellschaft, vol. 14, \^'n<, p. 36. \WJ. (An. .n. Some potato diseases. The Journal of the Board of Agriculture, vol. 9, 1902 ::. p. 307. 1902. Carri rHEBs, W. Diseases of trees and plants. The Journal of the Royal Agricultural Society of England, vol. 63, 1902, p. 288. 190:.'. Potter, M. C. \ new potato disease (Chrysophlyctis endobiotica). The Journal of the Board of Agriculture, vol. 9, 1902 3, p. 320. L903. (Anon.) A new potato disease. The Agricultural Gazette, vol. 57, 1903, p. 26. 1903. (Anon. The warty disease of potatoes. The Gardeners' Chronicle, vol. 33, L903, p. 329. 1903. Carruthers. Potato canker in Lancashire. The Journal of the Royal Agricultural Society of England, vol. 64, 1903, p. 305. 1903. Cooke. Potato tumour (Oedomyces leproides Trab.). The Journal of the Royal Horticultural Society, vol. 27, 1903, p. sir,. 1903. Cooke. Warty potato disease. The Gardeners' Chronicle, vol. 33, 1903, p. 187. L903. MacDougall, R. Stewart. New fungus disease of potatoes. Transactions, Highland and Agricultural Society of Scotland, ser. •">, vol. 15, 1903, p. .".12. 1904. i Anon.) La plaque noire des pommes de terre. Bulletin Mensuel de 1' Office de Renseignements Agricoles, vol. 3 1904), no. 8, p. 924. 1904. (Anon.) Black sc&b .(Oedomyces leproides Trab.). Queensland Agricultural Journal, vol. 15 | 1904), no. 2, pp. 605-607. 1904. (Anon.) Black scab. The Agricultural Gazette, vol. 59, L904, p. 268. 1904. (Anon.) Black scab of. potatoes. The Agricultural Gazette, vol. 59, 1904, p. 368 1904. (Anon Black scab of potatoes (Oedomyces leproides Trab.- Chrysophlyctis endobiotica Schilb. ). Leaflet no. 105, Board of Agriculture and Fishi I Ion, April. 1904. 1904. Eastham, J W. Black scab of potatoes. Yearl k, College of Agriculture and Horticulture, Holmes Chapel, 1904, pp. II 13. 1904. Massee, George. Some diseases of the potato. The Journal of the Royal Horticultural Society, vol. 29, 1904, p. 139. 1904. Massee. Black scab (Oedoi roides). The Gardeners' Chronicle, vol. 35, 1904, p. 257. 1904. R.N. Warty potato diseas Phe Gardeners' Chronicle, vol. 36, 1904, p 372. 1905. Carbuthers * Shrysophlyctis endobiotica canker. The Journal of the Royal Agricultural Society of England, vol. 66, 1905, p. 167, 1905. Greaves, H. Wartydisea f potatoes. The Gardeners' Chronicle, vol 38, 1905, p. 346. 1905. Gbove,W.B. Warty disease ol potatoes. The Gardeners' Chronicle, vol. 38, 1905, p. 308. [Cir. 52] 9 10 W ART DISEASE OF THE POTATO. 1906. (Anon.) Black scab of potatoes in North Wales. The Joarnal of the Board of Agriculture, vol. 13, 1906-7, p. 441. 1907. (Anon.) Warning. The Journal of the Board of Agriculture, vol. 15, 1907-8, p. 119. 1907. (Anon.) Warning to potato growers. The Agricultural Gazette, vol. 65, 1907, p. 279. 1907. Borthwick. Warty disease of potatoes. Notes from the Royal Botanic Gar- den, Edinburgh, no. 18, August, 1907, pp. 115-119. 1907. Dean, A. Black scab in potatoes. The Gardeners' Chronicle, vol. 42, 1907, p. 417. 1907. Riehm, E. Der Kartorfelkrebs in England. Central) ilatt fur P.akteriologie, Parasitenkunde, und Infektionskrankheiten, vol . 24, 2d part, 1907, pp. 208-213. 1907. Salmon, E. S. "Black scab" or "warty disease" of potatoes (Chryso- phlyctis endobiotica Schilb.). The Gardeners' Chronicle, vol. 42, 1907, p. 397. 1907. Salmon, E. S. "Black scab" or "warty disease" of potatoes. (Chryso- phlyctis endobiotica Schilb.). Bulletin of the County Councils of Kent and Surrey, 1907. « 1908. (Anon.) Black scab in potatoes. Journal, Department of Agriculture and Technical Instruction for Ireland, vol. 8, no. 3, April, 1908, pp. 441-443. 1908. (Anon.) Wart disease (black scab) of potatoes. The Journal of Horticul- ture and Home Farmer, vol. 57, 3d ser., 1908, p. 457. 1908. (Anon.) Wart disease (black scab) of potatoes. The Journal of the Board of Agriculture, vol. 15, 1908-9, p. 671. 1908. (Anon.) Potato scab and legislation. The Gardeners' Chronicle, vol. 43, 1908, p. 235. 1908. (Anon.) Some potato diseases. The Gardeners' Chronicle, vol. 44, 1908, p. 146. 1908. (Anon.) Warty disease in potatoes. The Gardeners' Chronicle, vol. 44, 1908, p. 266. 1908. (Anon.) Black scab of potatoes. The Gardeners' Chronicle, vol. 44, 1908, p. 449. 1908. (Anon.) Varieties of scab in potatoes. The Journal of the Board of Agricul- ture, vol. 15, 1908-9, p. 749. 1908. (Anon.) Black scab in potatoes. Leaflet No. 91, Department of Agriculture and Technical Instruction for Ireland, 1908." 1908. Appel, O. Der Kartorfelkrebs. Illustrierle Landwirthschaftliche Zeitung, vol. 28, 1908, p. 832. L908. Johnson. Potato black scab. Nature, 1908, p. 67. 1908. Josting. Der Kartorfelkrebs. Deutsche Landwirtschaftliche Presse, vol. 35, 1908, p. 883." 1908. Potter, M. C. Note on the warty disease and corky scab of the potato. The Journal of the New Castle Farmers' Club, July, 1908. a 1908. Potter, M. C. The warty disease of the potato. Gardening, vol. 130, 1908, p. 456. 1908. Schneider. Eine eigenartige neue Kartoffelkrankheit in Deutschland. Deutsche Landwirtschaftliche 1'resse, vol. 35, 1908, p. 832.a liius. So i:\ukr. Handbuch der Pflanzenkrankheiten, vol. 2, p. 116. " Reference not verified. [Cir. 52] w Ai; I DISE ASE I IF CHE POTATO. 11 L908. Spibckermann. Ueber das \ orkommen von < 'hrysophlyctU thdobiotit a Schilb. in Westfalen. Praktische Blatter fur Pflanzenbau and Pflanzenschutz, vol. 6, October, L908, p. I 13 1909. Ericksson, J. rlvitrota och Kriifta 6 potatis. Centralanstalten for Jord- bruksfdrsdk, Flygblad, no, 8, February, 1909 L909. Grosser. Der Kartoffelkrebs: Zeitschrifl der Landwirtschaitliche Kammer furd. Provinz Schlesien, vol. L3, L909, p. 61 1. L909. Gttssow, II. T. \ serious potato disease occurring in Newfoundland. Bul- letin 63, Departmenl oi Agriculture, Central Experiment Farm, Ottawa, Canada, October, 1909 1909. Johnson', T. Chrysophlyctis endobiolica Schilb. (potato wart it black scab) ami other Chytridiaceae. The Scientific Proceedings of the Royal Dublin Societj . vol. 12, no. l I, June, L909 L909, BLreitz. Mitteilung fiber einige Kartoffel Krankheiten. Ulustrierte Land- wirthschaftliche Zietung, vol. '-■>, 1909, p. I7»i. L909. l'laa i\ w, John. New fart- concern in;,' warty di-ea-e i>l potato. The i.;ir- deners' Chronicle, 3d Ber., vol. 16, no. L179, 1909, p. 7'.». L909. Remy, T. Her I la. kit iuhtl.au, vol. 1, Der Kart.iffell.au. Berlin, 1909, \>. 135. 1909. Riehm, E. Der Kartoffelkrebs und seine Beksimpfung in England. Illus- trierte Landwirthschaftliche Zeitung, vol. 29, L909, p U5. run. Divers, W. II. Wart disease of potatoes. The Gardeners' Chronicle, vol. 47, 1910, p. 13. Approved: James Wilson, S( <■/; tary of Agriculture. Washington, D. C, Febntary ' h 1910. [fir. 52] o UNIVERSITY OF FLORIDA 3 1262 08928 9747