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DEPABTMBNT OF AOWCULTURB

CEJSTTRAL EXPERIMENTAL FARM

OTTAWA. CANADA

DTVISION OF BOTANY

A SERIOUS POTATO DISEASE OCCURRING IN
NEWFOUNDLAND

H. T. GtJsSOW

BetimUi to fh* Dommion Bxperintittal Farmt,
Ottawa, Ont.

BULLETIN N"o. 68

POTOBKB, leOO

630.4

C212

Exp. Farms

Service

Bui.

f dirMtion «f th« Hon. SYDNEY A. RSHER. Minittw of Agricuituro, Ottaw., Ont.

** J -'.V

DEPARTMENT OP AGRirTTLTURE

CENTRAL EXPERIMEiNTAL FARM

OTTAWA. CANADA

DIVISION OF BOTANY

A SERIOUS POTATO DISEASE OCCURRING IN
NEWFOUNDUND

H. T. OOSSOW

Botanhl to the Dominion Experimental Farmt,
Ottawa, Ont.

BULLETIN No. 63

OCTOBB3R, lOO©

Publi.h.d by direction of the Hon. SYDNEY A. FI&HER. Mini.fr of

Aoricultur*, OtUw^ Ont

To the noTionrab1«

The MinUtar of Ajrrfrnltnre.

8m,— I ber to lubmit for your approv*! Bulletin No. 63. entitled : ' A Rerioui PoUte
DiMue occurring in Newfoundland' which hu been prepared by Mr. H. T. OUsaow,
Boteniit to the Dominion Experimental Farm*. la thia buUetin reference i« made to
the exiitenco and progn-ea of the diaeaie referred to, ia Great Britain and in Europe
for aome years pMt. where it ii known aa the PoUto Canker. From ll.o facta brought
together in thia Bulletin, reUting to the life history of this disease in Europe, and iu
discoTcry by Mr. Oiiaaow in poutoee sent from Newfoundland, it is evident that ita
occurrence in America ia a Tery aerioua matter and every effort poaaiblo should be
made to limit the spread of thia diseaa«>. and to destroy ihc diseased tubers whenever
they are found.

All the illustrations used in this Bulletin are original and have been prepared by
Mr. Gttssow, who has studied this disease in Europe, and hence haa been nblo to give
full details of its life history.

This deaoriptive matter with the illustration* wiU, it is hoped, enable any one
to recognize Potato Canker wherever it may occur.

I have the honour to be.

Your obedient servant.

Ottawa, October 87, 1909.

Wm. SAI'NDERS.
Director of Experimental Forme.

OUTBREAK OF A SERIOUS POTATO DISEASE
IN NEWFOUNDLAND

POTATO CANKER (Chryaophlyctis endobiotica, SchUb.)

ir. T. GU8.SOW, P.R.M.8.
JlotaHUl to tht Dominion XxpninutUal furma, Oltaum

nrntoDuonoir.

During the past 13 year* a teriout potato iiinlady hai been rapidly upreadlng in
European countriea. The di*mM. which naa been kno«-n in England since 1901, haa
received in that country the foUowing namea: Black Scab, Warty Disease, Cauliflower
Dueaae of PoUtoee. but it ia more properly designated aa PoUto Cnnk-r. It has
hitherto been unknown on the continent of America, but haa n-iw made iU appearance oi
thia aid* of the AUantic. having been recognized by the BoUnist of the Experimeuti. I
InnlT*' '••••"^ tpecimtna of potatoea forwarded from a locality in Newfound-

While it ia not very likely that potatoea will be imported to any extent from New-
foundland into Canada, yet the extraordinary virulence of the diseaae in Great Britain,
and the remarkable rapidity with which it haa spread over practically the whole of
Europe, maka it neccaaary to iaaue a warning to all growers of potatoea to be diligently
on the lookout for thia aerioua malady. There ia hope that the diaeaae may yet be
nrreated before ap-Mding to other localitiea, if Umely notice be given to the potato
growers of the Dominion. The investigation which haa been personally conducted into
the natuiw of the diaeaae^ by the writei in Great BriUin, provea that it ia one of the
most serious maladiea known. Where allowed to establish itself, it renders the culti-
vation of pot?* -a extremely difficult. It ia not desired to unnecessarily alarm the
growen of r », but it muat be borne in mind, that if thia disease ia through in-

difference or . ^.igence aUowed to eatabliah itself in Canada, there is no hope of being
able to aave a crop that is once attacked; moreover, the ground on which a diaeaae^
crop may have been raiaed, will be unfit for the cultivation of thia important crop again
for a period of six yeara. In thia oonnection practice and acience must, aa alwa-^ go
hand in hand, and if our object inkeepbg the diseaae out of the Dominion, be atttiined
everybody who thus renders assistance, will deserve credit fo.- aaving the potato
growera of Canada from disastrous losses.

Hiitory of the Diieaae.

The first existing record of the disease is attributed to Prof. Schilberszky. who dis-
covered the disease in Hungary, in 1896. («) In December, 1902. the Journal of the
English Board of Af culture published an account of this disease by Prof. M. C.
Potter who referred its cause to the same fungus as that described by Sohilberazky,
viz. Chry»opVyetit endohiotiea . Curiously enough, in the same number thia identical

XIV, 1896, p. 36. (cit. Soraoer. HanUbuch der Pflanzenkruikheiten, 1MB. Vol. 2, p. 116.)

diiMM WM flMcribnl bjr Mr. UeoriD Ma«aM of K«w, who, how«T«r, tpfrrxttl it to ih*
fMiua Otdumytu (ip. Itproidi; Trabul), • dliMM which wai rtmtnkil w nopurrinC
on bM>t-root in Alfcria, but which aoconliiiir ti) information rtveired by the writer
from Prof. Tnbut, it duo to a Inlalty diffirrnt oriraniam than that on the potato, Th*
Icalict of tha Bo«rd of Affriciiltura ami FiiheriM No, lOS, publi*h'd aubaMiuantly,
rvprati the prrar in identifteation of the diieaaa at one that i» caused bjr (Eiompett
Uftroid—, trMtlnr It aa ■ynnnymou* with CkrfopMgrtit mdohinlim.

Although the i«riou«neM of tha diica*'' waa raooipiitad, no ■]rit<*niati« atapa were
taken to top it from iprradinc, until it wa« aehoduled an a notifiable diaeaae by the
' Daatructlve Inaect and Pceta Onler o{ IBM' (iMiicd under the Peslnirtiv»
Inaaot and Peata Acta, 1877 to 1007) which renden penmna conccalinir thi* diw>nM<
liable to proM*cution and a heavy p^alty. During tlie yeare that hare elapM<l
ainoe the diteaae made ita flrat appearance in Knirland in 11)01, it har alowly
but aurely upread from county to county and during the year IDOS, 844 caaea were
^'portod to the aullioritioM under the new Act. The diicaic now pri'vail* in Irclaml and
Hcotland and wa« recently recorded aa appearing in Scandinavia, Oemiany, France
and Italy.

It !■ now prernlent over the greater part of Europe. From what haa been itoted,
it will be evident thnt a moat aeriou» peat haa to be conilofrd. In or»':'r thnt "t ma.v l>o
poaaible to recognize the diaeaae in nil ita atogea it ii tit HJrablu to deacribe carefully
ita

AppearaiiM in the Field.

The diaeaae ia unfurtunati'ly nut noticeable, until the potato crop it being har-
vested, thiia the diaeaae i« lialiie to contaminate the ground, without being obaerved,
an ia not the cnie with ditcaaca affecting plnntn ut>ove ground, auch aa ' Late blight,'
I'lillfoiilithorii infenlani, (Mont.) de llary.

Where the diicaae ia prevalent, practically no hcoltli.v tubcra will de\'clr>p. The
tul'cra when lifted, thow aigni of vnriouK degrret of injhry. Some appear on caaual
cxamin ititm to be aound. fiut the ' eyca ' of the tubera xhould be carefull.v pxaniinod,
tlioup arc till' places where the diseiiKo ix first noticeable. The eyes of BiT"ctcd tiibcra
sliow an abnormal development of the dormant shoot. A careful untrained obacrver
can eaaily recognize the presence of the <li«en!>e in this stage. At the same time it is
in this condition tlint the disease is most liltely to escape detection and to be spread
by menns of infected tubers used for teed. In the earlier stages of tlio di«cas<\ the
eyes will be f nind to be slightly protrudinjr in tlie form of u siiiple or comjHiund
group of amnll nodules vorying from the sire of a pin't hend to that of a pea. Figure
1 ' A ' show* n section through a tuber slightly affecteil. the nodules being plainly
visilde nt four points where in healthy tubers eyes would Imve l)een situated.

Hf^

I'iU. I.- IVlTtNBI SHOWINS DuUM Of r<lfA10 CaHKU CI'T IN IlikLVPK

A. — A tubor showing (our *yt aeknl by th* fuogui Chr|/iuph{tfch'i fHi/ubiolira, Bcbilb.

B.— A tubrr ■howing upp*r tjrc onljr attackiHl.

C— A tuber half oortred bjr tbe •scrtucvocm uuiwd by tbt fanfni.

When a>i iiifpcted potato it washed in water, thii tmall i odule is enxily <)!«•
tinguishablu from a sound eye by its colour. Tbo colour of a souml eye may Ik> wliiti',
rose or purplish, while the diseased nodule is ot' a ruHty lirown colour showing ito
resemblance tu an eye of the potato, with which every grower ii« doubtless funiiliur.

There can be no doubt that Ihc iliscasc was introducinl into Ncwfoundliuiii t>y
means of disoase<l seed tubers, imported from infected arcoM, and it must be 8tri<-tly
emphasized that the examination of every tuber thnt ia planted \* one of the nurPHt
ways of keeping the disease out. No suspected tubers shouM be planted; they should
be kept separate and samples be sent to tha liotanist, Central Kxperimental Farm,
Ottawa, who will gladly exiinine such annipica un-l report whether *io «ii«peeted tuln'r«
are diseasiHl or not. Considerable looses may be averted by sue! .■cautions and tlie
care token when planting xoiind p<Jtutoea will be amply ropaid larvc-t time. It'
diseiiwd tubcrii bo planted, the crop may b^ doomed, t '<> lond \ .n be infected, tho
diseasi! will have Rained n foothold and the future ' 'iltivntiv u of potatoes thro\iKli<>iit
the country moy be wriously influenced. Great care siiii.ld be taken, when pliiiiting
potatoes, especiflUy when imported from vr\ lart of Ei. v- to ascertain whether the
seed t\ibers tome fr<im infected areas. Wh. Ic, i s already t>tp.ed, there may be but slifrlit
dnnger of importing seed tul)ers from JJew..^ .i.dland, yet, thiit the disease may be in-
troduced in this way, is not impossible, especiolly as the extent of the distribution of
tho disease cannot be accurately ascertained at the time of writing.

Further (stuges of the disease are as follows: Some tuln-rs will be found, when the
crop is harvested, with more or less than one-half of them covere<l by these jirMltiliir
excrosieence-t which may be larger, than the original tuber itself. Figure 1 'R' mid
'C plainly show the features of this stage when the diseased tubers are cut in
halves. The growth consists here of a mass of coral like, or more or less senly cnQ-n^-^-
eence^ or nodules similar in appearanee to the well known crown or root gall of apples.
The adherent earth can be easily washed off when the character of the growth becomes
more apparent. It is not spongy- and not detachable from the tuber. It is of a somewhat
lighter colour at the bnse and dotted with minute rusty brown spots over the surface.
In nn advanced stage the tubers are wholly covere<l by 'his growth, having lost every

TMemblance to potatoet. They are lumps as will be seen in figure 3, ' A ' and ' fi '
of irregular outline, never spherical or oblong, but simply a mass of ragged and edged
excrescencea. Figure 9, ' A ' represents a whole plant as dug from a diseased field of
potatoes. It clearly ahows the extraordinary change which the tubers undergo. Right
in the centre of ' A ' a tuber will be noticed, comparatively little attacked, showing
however, plainly the excrescences by which it is covered. The two dark masses repre-
sented in ' B,' fig. 2, are potato tuWrs totally covered by the disease as just described.
A still more advanced stage occurs, when the fungus has utilized every particle of food
stored in the tuber and has reduced it to a brownish black soft mass, giving ofi a
very unpleaitant putrefactive odour. This is the most dangerous stage of the disease;
and tubers whidi have reached it cannot be harvested whole, they break in pieces
and thus the brownish pulpy mass, consisting almost entirely of the spores of the
fungus 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. Infected soil wiU for ysars pro-
duce unsound crops and here we have another ridt in the dissemination of the disease,
by the carrying to uninfected areas infected soil adhering to the boots of workmen or
to farm carta and implements. It should be stated that though the disease is most
conspicuous m the tubers, cases have come to the author's notice where the haulnm
and lateral branches of the plants above ground were attacked by the fungus, showinp
more or lees largg clusters of excrescences, exhibiting, through the influence of light
acting on the colouring matter in the plants, a somewhat leafy greenish appearance.

Damajre Caused by the Disease.

It has been stated that no sound tuber is saved from a crop that is attacked.
While the virulence of diseases like 'Late blight' or 'Early blight' (AUem^ria
solani, Sor.) are more or less dependent upon climatic conditions, this disease is not
influenced in any known degree by physical or mechanical conditions. It may, there-
fore, be considered as the most serious pest attacking potatoes. Fields, at harvest
time in a£Fected areas, present the most hopeless appearance; the dioease has caused
the greatest havoo in all localities where it has appeared.

Pathology of the Disease.

The fungus Chryiophlyctis endobiotica, Schilb. belongs to the order of Chytridinece,
the genera of which produce no mycelium like the main groups of fungi. It reproduces
itself by resting sporangia in which numerous swarm spores are formed. When examin-
ing a diseased tuber, cutting right through a portion of the abnormal growth it will
appear as represented by the illustration, fig. 1 ' A,' ' B,' ' C Gutting a fine section
of one of the nodules and examining it under the microscope one can easily detect the
parasitic organism lying closely under the surface and masses of which cause externally
the rusty-brown dots already mentioned. Figure 3 ' A ' represents a micro-photograph
reproduced from such a section, showing plainly the diseased organism in the form
of black dots living in the external oells of a diseased nodule. The diseased tissue is
not covered by a protective epidermis. The cells immediately on the surface show
under the microscope more or less sharply defined round or oval colourless bodies which
represent earlier stages in the life-history of the fungus. The irritation caused by these
organisms in the potato produces a prolific outgrowth of enlarged (hypertrophied) cells,
which are attacked from the outside by means of minute swarm spores of the fungus.
These renewed attacks, give rise to a continuous production of cells and the large
excrescences result as shown in the figures. Lying closely underneath the colourless
bodies, will be found the resting sporangia of the fungus. They are from oO to 70
micromillimeters in size and are gobular to oval, dark-brown, transparent bodies with
no lateral depressions, and the surface of which is covered by slightly darker brown
ridges composed of the membranes of the cell walls which protect the contents.
Figure 3 ' B ' is reproduced from a highly unlarged micro-photograph and gives an
idea of the size, shape and number of these resting sporangia. The original object from

which thii photograph wu taken waa less in size than a pin's head ; the number of
these organisms may be easily estimated from so small an object. For the information
of pathologists it may be mentioned that the resting spores appear almost lil<e those
of the Perono*porecf. The contents of these spores appear as a granulated mass un<ler
the microscope. The artificial germination of the resting spores has proved of extra-
ordinary difficulty. For many years all experiments to germinate the spores resulted
in failures, and the life-history of this obscure fungus remained unknown until quite
recently, when Prof. T. Johnson, of the Royal College of Science, Dublin, succeeded
in discovering the germination of the resting spores. As it was expected, the walls of
the sporangia split, allowing the escape of numerous Oospores. A new infection takes
place by the penetration of these swarm or zoospores from the soil or by the internal
passage of Plasmodium from diseased tubers, used as seed, to the new tubers formed
on the plant. Potato tubers completely decomposed by this disease have been collected,
dried thoroughly and kept in this condition for some years. These were afterwards
mix"d with soil and, whon sound tubers were planted in the soil so inoculated, the
disease reappeared vigorously. This illustrates plainly the longevity of the spores ol
the fungus by which the disease is spread.

Method of dealing with the Siieaie.

The appearance of a diseased crop has already been indicated ; when a grower finds
hif crop attacked, he may hesitate to destroy potatoes which appear sound or but little
aflected, althoujih total destruction would be the best means of preventing the spread
of the disease, yet those tubers may be collected, boiled and be fed to pigs. Und^r no
circumstances should unboiled or decayed potatoes be given as food. Not only becauso
the feeding value is sure to be reduced, but mainly because the spores are still capable
of germinating after passing through the body of an animal. In removing the potntops
from the field, the greatest precaution should be taken to clean thoroughly and disinfect
one's boots and the farm carts and implements used. Straw may be used to wipe off
the adhering soil and everything to which soil adheres should be washed with a 1 in
800 solution of Bichloride of Mercury or Corrosive Sublimate. The process of dis-
infecting may be carried out on boards laid on the field, &c., so that no reinfection
take place afterwards. The grower should then proceed to dig a hole in the field and
collect all refuse from the vines and all diseased tubers. The potato straw should be
destroyed by fire; hut the tubers, being too wet to bum, may be dealt with as follows : —
The hole that has been dug must be big enough to hold all the tubers collected; it
should then be covered with a layer, 6 inches deep, of unslaked lime ; then a portion of
the tubers may be thrown in and covered by another layer of unslaked lime, and so
on till the hole is filled. The last layer should be formed, of course, by the lime. In
this manner the tubers are put out of harm's way. In some localities unslaked lime
is difficult to obtain. For these districts may be recommended a quantity of sawdust
thoroughly soaked in a 1 in 600 solution of Bichloride of Mercury. This should be
mixed after soaking, with the tubers that are to be destroyed. The tubers may then
be buried. These pits should be dug in some portion of the field where they may
remain untouched for three years. When the land is thus cleaned, it should be fallowed
and treated with unslaked lime at a rate of 4 or 6 tons per acre. Where lime is nnt
obtainable, one must resort to the spraying of the ground with a 1 in 800 solution of
Bichloride of Mercury by means of a liquid manure distributor or potato or any other
kind of sprayer. In fields worked on a four course rotation, growers should replace
the potatoes by some other crop. Any other crop may be grown.

PreTention of the Disease.

Under no circumstances should seed potatoes from a diseased crop be used. If
'seed' is suspected of the disease, the sets should be powdered with sulphur and be
stored in boxes until planted. Four or five lbs. of sulphur suffice to treat one ton of

potatoei. Examine carefully eveiy tuber before planting, or submit them to an expert,
/nquire carefully, when buying seed potatoes, where they come from, and guard
against using any from infested areas.

C0HCLU8I0V.

1. The disease known as 'Potato Canker,' 'Black Sonb.' 'Warty Dis-nse' and
a^J!vl'**'T"v^'*^"** °* Potatoes,' due to the fungus Chrynophlyctit endoliotica.
SchJib., which caused severe losses amongst European potato crops, has for the first time
appeared on this side of the Atlantic, being reported from a locality in Newfoundland.

2. Growen or consumers of potatoes must guard against the introduction of this
disease into the Dominion of Canada by selecting sound potatoes for cultivation and
by stnclly rejecting any thmt appear diseased.

3. As yet, no case of the disease has been recorded from any locality within the
Dominion. In the event of the disease appearing, samples of tubers should be sub-
mitted without delay to the Botanist, Central Experimental Farm, Ottawa, for exam-
ination and advice.

4. Specimens of this disease preserved in alcohol will be sent to any agricultural
institution or college for the purpose of having type specimens for reference, as soon
as ready.

6. Copies of this bulletin may be had free of charge on application to the Central
Experimental Farm, Ottawa.

6. The present bulletin has been prepared as a warning, in the hope that all
potato growers, merchants, gardeners and private individuals will take immediate steps
to report promptly any cases of the disease which may come to their knowledire and
so join in preventing the spread of this serious malady which has unfortunately
assumed such dangeroua dimensions in Europo. ^

Fio. 2.— Potato Ca.nkkh.
A A plant .if diseased i)otato..8 an it api>ean. when du(f ; showini? in the centre a
partially Hound tul*r«,vere<i with excrencvnc-s caused by t h ■ funfm-at the l«,sL • aL^
slmwinfr 81X nialfumied tubers adhering to the plant.
I!. Two tubers natural size badly diseased.
8127—2

Fio. 8. — Sconoits or iiibbasbo nuun or Potatoh AmcrxD bt Potato Caxkxb.

A. MictopbotoKraph of a im»U diwuect nodule ifaowiiwt uumetoiu ravtiiu sponuuriit
of the f uiiKu» Ijriiwclowly on the tnriace.

B. Fortiun <d th« nam wction mora highly magnilM ebowii^ ehape of the ■ponngU.