CIHM 
 Microfiche 
 Series 
 (l\/lonographs) 
 
 ICIVIH 
 
 Collection de 
 microfiches 
 (monographies) 
 
 Canadian Institute for Historical Microraproductions / institut Canadian da irticroraproductions historiquas 
 
Technical and Bibliographic Notes / Notes techniques et bibliographiques 
 
 The Institute has attempted to obtain the best original 
 copy available for filming. Features of this copy which 
 may be bibliographically unique, which may alter any of 
 the images in the reproduction, or which may 
 significantly change the usual method of filming are 
 checked below. 
 
 D 
 D 
 D 
 
 D 
 
 D 
 
 Coloured covers / 
 Couverture de couleur 
 
 Covers damaged / 
 Couverture endommagde 
 
 Covers restored and/or laminated / 
 Couverture restaur^ et/ou pellicula 
 
 Cover title missing / Le titre de couverture manque 
 
 I Coloured maps / Cartes gdographiques en couleur 
 
 □ Coloured ink (i.e. other than blue or black) / 
 Encre de couleur (i.e. autre que bleue ou noire) 
 
 □ Coloured plates and/or illustrations / 
 Planches et/ou illustrations en couleur 
 
 FT] Bound with other material / 
 
 Reii^ avec d'autres documents 
 
 Only edition available / 
 Seule Edition disponible 
 
 I /] Tight binding may cause shadows or distortion along 
 
 D 
 
 interior margin / La reliure SBTT6e peut causer de 
 I'ombre ou de la distorsion le long de la marge 
 Int^rieure. 
 
 Blank leaves added during restorattons may appear 
 within the text. Whenever possible, these have been 
 omitted from filming / Use peut que certaines pages 
 blanches ajout^es lors d'une restauration 
 apparaissent dans le texte, mais, lorsque cela 6tait 
 possible, ces pages n'ont pas 6t6 filmtes. 
 
 Additional comments / 
 Commentaires suppl6mentaires: 
 
 L'Institut a microfilm^ le meilleur exemplaire qu'il lui a 
 6\6 possible de se procurer. Les details de cet exem- 
 plaire qui sont peut-dtre unk^ues du point de vue bibli- 
 ographique, qui peuvent nrxxlifier une image reproduite, 
 ou qui peuvent exiger une modifk»tion dans la mdtho- 
 de normale de filmage sont indiquds ci-dessous. 
 
 I I Cotoured pages / Pages de couleur 
 
 I I Pages damaged / Pages endommagtes 
 
 □ Pages restored and/or laminated / 
 Pages restaur^s ot/ou peiiicul^es 
 
 r~> Pages discoloured, stained or foxed / 
 I — I Pages dteolordes, tachet6es ou piqutes 
 
 I I Pages detached / Pages d^tach^s 
 
 \\/] Showthrough/ Transparence 
 
 
 D 
 
 D 
 
 D 
 
 Quality of print varies / 
 Quality inhale de I'impression 
 
 Includes supplementary material / 
 Comprend du materiel suppi^mentaire 
 
 Pages wholly or partially obscured by errata slips, 
 tissues, etc., have been refilmed to ensure the best 
 possible image / Les pages totalement ou 
 partiellement obscurcies par un feuillet d'errata, une 
 pelure. etc., ont 6\6 1\\m6es k nouveau de fa^on k 
 obtenir la meilleure image possible. 
 
 Opposing pages with varying colouration or 
 discolourations are filmed twk:e to ensure the best 
 possible image / Les pages s'opposant ayant des 
 colorations variables ou des d^olorations sont 
 film^s deux fois afin d'obtenir la meilleure image 
 possible. 
 
 This Kain it filimd at ttw raduetion ratio chackad b«low / 
 
 C0 dOCUITWnt Mt ntfnv Ml tMIX 00 fBOUCtiOn InoiQuv Cl*ClSSSOtM. 
 
 lOx 
 
 
 
 
 14x 
 
 
 
 
 llx 
 
 
 
 
 22x 
 
 
 
 
 26x 
 
 
 
 
 30R 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 "7" 
 
 
 
 
 
 
 
 12x 
 
 16x 
 
 20x 
 
 24x 
 
 28x 
 
 32x 
 
Th« copy filmed h«r« ha« b««n r«produe«d thank* 
 to th« g«n«ra«ity of: 
 
 Library 
 Agriculturfl Canada 
 
 L'M«fnpiair« fiim4 fut raproduit grica A la 
 a4n4roait* da: 
 
 BibliotMqua 
 Agricultura Canada 
 
 Tha imagaa appaaring hara ara tha baat quality 
 poaaibia conaidaring tha condition and laglbiilty 
 of tha original copy and in kaaping with tha 
 filming contract spacificationa. 
 
 Laa Imagaa auivantaa ont 4t* raprodultaa avao la 
 plua grand aoin. compta tanu da la condition kx 
 da la nattat* da I'axamplaira fllm4, at wt 
 conformity avac laa conditiona du contrat da 
 fiimaga. 
 
 Original eopiaa in printad papar covara ara filmad 
 beginning with tha front eovar and anding on 
 tha laat paga with a printad or iliuatratad Impraa- 
 sion, or tha back eovar whan appropriate. All 
 othar original eopiaa ara filmad beginning on the 
 first page with a printad or illustrated Impree- 
 sion, and anding on the laat page with a printad 
 or iliuatratad impraaaion. 
 
 The laat recorded frame on eech microflehe 
 shall contain the symbol — ^^Imeening "CON- 
 TINUEO"). or the symbol ▼ (meening "END"), 
 whichever appliae. 
 
 Mapa. platea, charts, etc.. mey be filmed at 
 different reduction ratioe. Thoee too lerge to be 
 entirely included in one expoaure »n filmed 
 beginning in the upper left hend comer, left to 
 right and top to bottom, aa many framee aa 
 required. The follo%ving diagrams illustrate the 
 method: 
 
 Lea exemplairee origineux dont la couverture v\ 
 papier eat imprim4e sent fiimAs an commenpant 
 par la premier plot at an tarminant soit par la 
 damlAre page qui eomporte une amprainte 
 d'Impreaaion ou d'llluatration, soit par la second 
 plet. selon le cea. Toua las autrea axamplairas 
 origineux sont filmta an commanqant par la 
 premlire page qui eomporte une ampreinte 
 dlmpreeaion ou dllluatratlon at •n tarminent per 
 la demiAre page qui eomporte une telle 
 emprejnte. 
 
 Un dee symbolee sulvanta apparaitra sur la 
 demiAre imege de cheque microfiche, selon le 
 eae: le symbole — »>signlfie "A SUIVRE", le 
 symbole V signifie "FIN". 
 
 Lea cartaa. planches, tableaux, etc., pauvent Atra 
 filmAa A dee taux de reduction diff Arents. 
 Lorsque le document eet trop grand pour Atra 
 raproduit an un seul clichA. 11 sat filmA A partir 
 de i'angle supArieur gauche, de geuche A droite, 
 et de haut en baa. an prenant le nombre 
 d'imegea nAcaaaaira. Lea diagrammea suivants 
 liiuatrent la mAthode. 
 
 1 2 3 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
MKXOCOfV RBMUTION TBT CHART 
 
 (ANSI and ISO TEST CHART No. 2) 
 
 Ui|2i 
 
 1 |Z5 
 
 KS^ 
 
 ■ Ih 
 
 lu |££ 
 
 ■ 2.2 
 
 Hfug 
 
 ■in 
 
 
 l£ 
 
 kku 
 
 U 
 
 1.4 
 
 Ul.6 
 
 ^ APPLIED IIVHg gi^ 
 
 j^^K 16S3 Cost Main Strttt 
 
 ^S^^ ('16) »»2 - OMO - Phon. 
 
 ^^^S ('«) 2M - :M9 - r„ 
 
DOMINION- OF CAXADA 
 
 DEPARTMENT OF AGRICULTURE 
 
 EXPEHIMKXTAL FARMS 
 
 J. H. QRI80ALE, B.Agr., 
 Diracter. 
 
 H. T. QiJSSOW, 
 
 Dominion BetanitI 
 
 DIVISION OF BOTANY 
 
 LATE BLIGHT AND ROT OF POTATOES 
 
 Caused by the fungus I'hytophthom infcttaru, dc Bary. 
 
 PAUL A. MUBPHV, B.A., M.R.C.S.L, 
 
 Assinlant in chaTge of II,,' Field Lahornton, for Plant I'abhology, 
 
 Charlottefown. F.E.I. 
 
 CIRCULAR No. lO 
 
 Publi.h.d by authority of Hon. (MARTIN BURRELL, Mini.t.r of Agrieultur.. Ottawa „ 
 
 nt. 
 
 92558—1 
 
 OTTAWA 
 
 G O V E K N M E .V T I> H 1 N T I N (} b R K A U 
 I'JK! 
 
_ , „ .. Ottawa. Fobruary 1. 1018. 
 
 lo till' lionourabln 
 
 The JJinisUT of Agriculture, 
 
 Ottawa. 
 
 Sir,— I have the honour to Hubmit herewith, for your upproval, Circular No. 10, 
 entitled • Ute HliKht mid Itot of rotatcK-s." wlildi hax bwn prepared by Mr. Paul A. 
 Murphy. Ansisttant iu charge of the Field Laboratory for Plant Patholony at Cliar- 
 lottetown. P.P:.I. 
 
 The subject treated of ia a most imiwrtant one. estjKHially to the potato gtovreK 
 of Quebec and the Maritime Provinces, and I would recommend a wide distribution 
 of this circular, in order that the efficacious preventive measures given herein maT 
 become generally known as soon as possible and heavy annual losses thereby avoided. 
 
 I have the honour to be, sir. 
 
 Your obedient servant. 
 
 J. II. ORLSDALE. 
 Director, Dominion Experimental Farm*. 
 
 92,5J8— 1J 
 
DiTMION (IK BoTANV, 
 
 Cknthai. Fxi'khimkntai. Farm, 
 I ,r -. „ „ . Ottawa, January JT, lOK!. 
 
 J. rr. (iiiisi)AiK. eki., n.Afcr., 
 
 Din-ctor, Experimoiital FarinK, 
 
 Dt'purtment of A(rri(mltun>, Ottuwa. 
 
 ■SiH.— I have tlie honour to fimginit herewith a manuncript entitled " Late Bllirht 
 and Rot of Potatoe*" cauxed by the fun^uii Phylo,,hlhora infr»tan», preparetl nt my 
 re.,ue«t, by Mr. Paul A. Murphy. B.A.. M.R.C.S.I., A«»ii.tant in charge of the Field 
 Laboratory for Plant Patholofry, ("harlottetown, P.E.I. 
 
 Lnto Blight iH recogniicd a» one of the n.o^t deiitrurtivo plant diwaiw in the. 
 world. In certain year, it has eau«)d incalculable \m»e*; yet them cui i« reduced to » 
 minimum by thorough and timely spraying with Bordeaux mixture. Experience and 
 exiierimcntB have shown again and again that when thi» ig done according to the- 
 clear and Mmple iuHtnictionH given by Mr. Murphy in thin circular, this practice i» a 
 profitable one every year and a very profitable one in yearn when Late Blight ii 
 prevalent. 
 
 I would respectfully n-cmmend the publication of this manuscript a^ I'irculal 
 No. 10 of the Experimental Farms publications. 
 
 I have the honour to be, sir. 
 
 Your obedient servant 
 
 H. T. tlL'SSOW. 
 
 Dominion Botanitt. 
 
LATE Br.KiHT AND ROT OF POTATOES 
 
 ('mumhI I.,v th«- fiiiiuu* I'hitlniihlhora infftUHM. ili- llary. 
 
 PAI'r. A. MTKI'llY. B.A.. M.R.S.rj.. 
 
 Ax-iiifanl in ritaryr «/ Ihe Fiild Lahoralory for I'lnnt Pathology 
 Charlotlelown, I'.KJ. 
 
 Fow pluiit diKMira nn. m> widiiipnad uml (iratriic-tivf ni< thi» Late Bli(cht of poU- 
 toon, uiid iilthouKh it i* not «> dr •udiil nor mi dii<frurtivc, apiwrpntly, now a* when 
 Hevfiity yjurn uko in KiimiH- it fxert«-d «u<h an inHueiu-o on the coume of the hi»tory 
 of th.- world, it i» utill prot My aurpuiiM-d by f.w diMmMs in the lom which it occ«- 
 •ionit. 
 
 Bjmptomi. 
 
 Lite r.lljtht ix so-<'«lIe,l becBU«' it apix-aw after the leaf bliR t due to the funirua 
 Alhrnnria Solani which paniw^ Uy tJie numc of Kariy Bliuhf. Tlie two may he caaily 
 distiniruiHhed. The Early liliffht i» pn-vuient in July, and the *fM,U which it eauMn 
 an? i-linraeteri*titall.v dry. hrtiwn, and marked with a series of <-(,ne..ntrie rings. The 
 Late nii^ht mokes its appearance later on, in Auffunt and S.-iiteirber aa • rule. 
 •IthoiiKh it h always present loiiK before it is irem-rally noticed. The first spots are 
 usually on the lower leaves or on the stems. They are da'k brown to purplish black 
 in colour, sometimes surrounded by a rinir of li,fht i^reen. and they have a wat '-soaked 
 •pp«>ari>nce. In fine weatlier they dry up and become brown. If wether oe moist 
 they increase in site and number and may involve the whole pi. • causing it to lie 
 in a few days and fall into a peculiirly evil-sim>lliriK mo s. 
 
 On the lower surface of the leaves, the bligh spot* pv sent the appearance of 
 beintf <'overed with mildew, particularly around the mar/.n uf the dead areas. If the 
 weather is dry, this feature will be absert. The mi'.fi. ■ n made up of myriads of 
 spores of the funffus and of the minute s.^lW: which benr rhem. Spores, as they are 
 called, may be likened to seeds, the punwsc ot which the.v serve. It is through them, 
 when washed down into the soil by heavy rain, that infection is carried to the tubers. 
 
 An infected tuber is characterized by livid-coloured, sliifhtly shrunken areas on 
 the surface which are abnormally hard. The flesh inside is mottled here and there 
 with brown spots (see Plate. Tig. A) spreading around the margin ''n the early stages 
 and later Involving tlie whole tuber. The Ijit<' Rlight Rot is typically u dry one. but 
 it Bometimea happer.s that other organisms gain an entrance through the spots wliiuh 
 have been killi-d by the blight and cau.se a soft rot. This may bo seen in wet seasons 
 at digging time. Cn tlio other hand, th? amount of Late Blight Rot visible when the 
 crop is dug is often slight, even though the tops were severely attacked, whereas it 
 
( A ) A i*(>utu cut through ihowing effects of ' ' Late Blight " in tuber after storage, 
 (Fhoto H. T. UiiMow). 
 
 (B) Four rows of ptitatoet showing control of " Lat« Blight " by Hpmying. Note 
 all tO|M dtra<l in front without spray and nil Cups green in back which have lieen 
 sprayed. (PhoUi.T. A. Clark). 
 
shows up afterward during storage. In every such case the tubers carried the Kerni 
 of the rot within them from the field. If the temperature of the cellar is low. the 
 parasite may remain practically dormant in them during the whole winter, ready to 
 destroy the tuber, however, when the temperature ri«e8. This rot passes by a variety 
 of names, of which 'Dry Rot" is perhaps the commonest, although it is incorrect 
 Late Blight Rot is preferable. 
 
 life Hiitory of the Canial Organinn. 
 
 The cause of the disease is the fungus Phytophlhom infe^tam. As the name 
 "fungus" indicates, the imrasite is of the nature of a mould. It is made up of colourless, 
 thread-like, branching strands, so small that they are invisible to the eve, which burrow 
 m the leaf and in the tuber. It passes the winter in the tubers in a semi-dormant 
 condition. If the temperature be low. Some of the tubers in which it has hiborn.ited 
 are cut and used for seed and the fungus under favourable conditions grows int.. the 
 sprouts. The great majority of them it kills off so that they never produce n plant. 
 but a few manage to struggle on into dwarfed plants, the fungus growing up with 
 them and ultimately producin.- a crop of spores on their stalks and leaves. These 
 spores are so small that they are blown about by the wind, and when they alight on a 
 potato leaf, if there be moisture enough for tlum to Kcrnilnatc. they sprout in a 
 curious way. The contents of the spore break up into about a dozen fragments and 
 emerge through an opening, which now appears in the wall, and l)egiii swimming 
 actively about in the little drops of water on the leaves. These little bodies, which 
 move about like animals, are called swarm spores. After awhile they come to rest and 
 each germinates by putting out a small tube. This germ tube, as it is calltMl. has the 
 power of penetrating the leaf and causing a spot of blight. The spore itself, under 
 certain conditions, germinates in this way direct, without the production of swarm 
 spores, and it too can infect a leaf. 
 
 These three processes of spore formation, germination and infection can take 
 place only in the presence of sufficient moisture and a suitable temixrature. Both 
 spores and swarm spores are quickly killed by drought and sunlight. This partly 
 explains why it is that, although the fungus is present in isolated plants from the time 
 they reach the surface of the ground, it does not spread to any extent until a month, 
 or perhaps two, later. Another reason may be that the plant is more sus<-eptihle at 
 and after blossoming time than in its earlier stages. 
 
 But although the blight is not observable for the first two months of the plant's 
 growth, it is established in little centres here and there under favourable circum- 
 stances t.. produce a crop of spores which the wind will scatter all over the field. The 
 rapidity with which this can take place, an attack appearing from nothing and from 
 nowhere, as it were, is well known. Recent investigation has shown, however, that 
 there are centres of infection unobserved in the field and the actual spread of the 
 disease from them has been noted. It was formerly thought that the disease lived in 
 the soil, yet this is hardly likely. 
 
 When a spore germinates on a leaf and infects it. the strands of the parasite 
 grow through its interior, feeding on the contents of the cells which it sucks out and 
 kills. A dead area results which wc know as a blight aiiot. This grows larger and 
 
10 
 
 InrRpr na the disoaae Rprcads out fi m the original point of infection, l<illinK tho leaf 
 as it goes. Tlien if the weather is moist, as the fungus luxuriates on the dead cells 
 it Koes to seed. On the lower side of the leaf of the potato plant there are innumerable 
 I reuthinp |)ores of a very minute size. Through these the parasite sends out one or 
 more hrniu-hed stalks on which the spores are borne. It is this crop of spores and 
 stalks which is often ao thick as to be visible to the eye in the form of a white mildew. 
 The spores readily drop from the stalks which bear them when they are ripe. Some 
 of tlu-ni arc borne by the wind to healthy leaves, perhaps in other fields, and some are 
 wii;<li<'d down liy the rain into the soil. If even one of the minute swarm spores comes 
 in contact with a tuber, it ean pierce its skin and set up the Late Blight Rot in it. 
 Thus the cycle is completed. If that tuber be planted next season it may communicate 
 the disease to the plant which arises fr-om it, and one plant is sufficient to contam- 
 inat-) the whole crop. 
 
 LoiKi Due to the Disease. 
 
 The annual loss due to this cause' all over the world is incalculable. In the United 
 States it was placed some time a(?o at $.36,000,000, and in some years it is greatly in 
 excess of this. Thus it is said : " Ten million dollars would be a conservative estimate 
 of the loss to New York potato growers 'alone in 1912, and the loss each year from 
 1903 to 1905 was even greater." Experience in Canada is not yet sufficiently exten- 
 sive to form a, general estimate, but in the year 1915, when Late Blight was admittedly 
 severe, tho loss in yield in Prince Edward Island was probably not less than 2.000,000 
 bushels, representing a value of $1,000,000. This entirely neglects the loss during 
 btorage. The amount of damage caused all over Eastern Canada would be about on 
 tho same scale, if anything rather more than less. 
 
 CONTSOL. 
 
 Late Blight can be controlled almost perfectly by spraying the potatoes about five 
 times with Bordeaux mixture made up of six pounds of copper sulphate (bluestone), 
 four pounds of (luicklime and forty imperial gallons of water. 
 
 For particulars as to making Bordeaiix see hack of this bulletin, where they are 
 placed for convenience in reference. 
 
 The first application should be made about the middle of July, and the treatment 
 must be continued evtry two weeks or so until the middle of September. No set rule 
 can be laid down, however, as to the date when spraying should begin, because it 
 varies so much in different locations and seasons, but with a little experience there 
 is no difficulty in fixing it. It is sometimes recommended to make the first applica- 
 tion when the plants are six to eight inches high, or about the time when it is neces- 
 sary to begin using poison for the potato beetle, and both of these are fair guides. 
 
 For putting on the spray over large areas, a horse-power sprayer, capable of keep- 
 ing up a continuous pressure of not less than one hundred pounds, gives the best 
 results. Several firms in Canada have such machines on the market, the price being 
 about $75 to $100. A machine of this kind should spray four rows and have three 
 nozzles to a row, two to spray upwards from between the rows and one to spray down- 
 wards. 
 
11 
 
 For those who grow on a somewhat smaller soale, an outfit coiisiatinn pKsontiRlly 
 of n barrel fitted with a hand pump, the whole to W plaeed on a oart, will lie thr most 
 UBcful. A sprayer of this tyiw to raver four rows can Im^ ohtainwl for $40 eoniiilete, 
 exclusive of the cart. The pump, nozzles and hose can also he pot separatfly. the 
 farmer supplying the cask. The pump alone costs $15 and care should be taken not to 
 get too small a size. Without a roikI pump, good pressure is impossible, and good 
 pressure is the first requisite for good spraying. Satisfactory work can be done, by 
 the exercise of care, with these macliincs, but naturally they are not so efficient as the 
 horse-power outfits. Machines to be carried on the back or in the hand, while they 
 do excellent work, are ordy suitable for garden patches. 
 
 Those intending to purchase spraying machines are urged *:> communicate with 
 the nearest Experimental Farm or the Dominion Botanist, Central Experimental 
 Farm, Ottawa, when further advice will be given. 
 
 The aim should he to spray hi-fore rainu perindx. not after. Once the spray dries 
 it is not easily washed off. Infeetien takes place during moist weather and spraying 
 nets only a.s a preventive of infection. It is Incapable of checking the spread of the 
 disease once it has got into a leaf. For the same reason the first application should 
 be made before the blight apiiears. Further, since the aim is to ])revent infcn-tion, 
 and since infection can take place on any part of the plant, the whole plant mu.st be 
 covered with the mixture. This is not as diflicult as it sounds, and with a little care 
 it can be successfully accomplished. Xeverthcloss, it cannot be too strongly urged 
 that thoroughness in spraying ttays and half measures are merely a waste of time and 
 money. 
 
 Spraying must be continued throughout August and part of September, even 
 though the vines clo.se in and cover the ground between the rows. Xot as much harm 
 as might be expected will be done by the wheels, and the increase in yield and soundness 
 of the crop will much more than compensate for whatever little loss there may be. 
 It would be well, however, to make the rows at least thirty inches at)art. Most experi- 
 ments show that this is the best distance, a fact which is borne out by the practise of 
 the best growers. 
 
 Fifty gallons may be enough to apply to an acre for the first spraying, when the 
 tops are small. Thereafter it will be necessary lo apply each time from seventy-five 
 to one hundred gallons or even more. 
 
 The nozzle for the delivery of the s|)ray is an imjiortant item. It sliould send 
 the mixture out in the form of a fine mist, the finer the better. The practice some- 
 times followed of pumping the spray out through a hose without a nozzle is extremely 
 wasteful and almost useless. 
 
 Profit from Spraying. 
 
 Experiments have shown that from five to seven very thorough sprayings („rrled 
 on over a inriod of ten years increased the yield at the average rate of !>'■:, bushels 
 per acre.* In some of these years there was no Late Blight, yet the increase was 
 always large enough to make the undertaking profitable. Five very thorough spray- 
 ings in Prince Edward Island in 101.') .jave an increase of 07 bushels of marketable 
 
 •At the New York Slate Experiment Station. Oeneva, N. Y. 
 
IS 
 
 potatoes per acre over unsprayed plots. The coat of gprayiiiK on a finid scale sliould 
 rot exceed $1 i>cr acre per gprayiiii;, and even at the present high price of materials 
 it should not eserod $1.60. On a smaller scale it mifrht cost $2, but even if it did the 
 increase in yield would still make it profitable. 
 
 The followiiif; table ^ives the cost of spraying o:i a larpc scale with a horse-|)ower 
 oiachine. The price of materials is that current in 1015 and is quite excessive: — 
 
 ITEMS IN COST OF SPRAVINO ONB ACRE OK POTATOES OXCE WITH BORDEAfX MIXTCBE OP 
 STRESOTII or 6.4.40 at the rate of 75 gallons per ACRE. 
 
 Hi pounds copper sulphate at 11 cents $1 .24 
 
 'i pounds lime at 1 cent 0.075 
 
 Three-quarters hour labour for man at 16 cents 0.12 
 
 Three-quarters hour horse labour at 10 cents 0.075 
 
 Depreciation on sprayer IC 
 
 $1.61 
 
 If we take the cost to be $1.61 per acre for every spraying and if spraying be 
 done five times the total cost will be $8.05. The profit from the spraying experiment 
 on Prince Edward Island, where the increase was 97 bushels per acre, was over $.34 
 per acre, in spite of the fact that, as it was merely an experiment and all the work was 
 done by hand, the spraying cost more than $14 per aTe. If a farmer cannot expect 
 to '«pray so thoroughly as to obtain an increase of 97 bushels he should not aim at 
 less than fifty. Even if the price of potatoes were as low as 25 cents jier bushel he 
 would still liave a profit of $4.45, and it is not unlikely in such a case that this figure 
 would conver* t'li- growing of that acre of potatoes from a loss into profit. 
 
 Preparation of Bordeaux Hizture. 
 
 The mixture recommended consists of 6 pounds of copper sulphate (bluestone), 4 
 pounds of quicklime and 40 gallons of water. This strength is commonly denoted by 
 the formula 6 :4 :40. Bordeaux mixture must be made up freshly each time it is used. 
 On the other hand the copper sulphate and lime may be each dissolved in water and 
 kept separately for an indefinite period, and this course is recommended. Suppose 
 an acre is to be sprayed five times at the average rate of 75 gallons of spray per acre 
 there will be required during the course of the season 5(ii poiHids of copper sulphate 
 and 37j pounds of lime. It is recommended that as much of these materials be pre- 
 pared in strong sjlution at the beginning of the season as the size of the vessels avail- 
 able will allow. These should be of wood — kerosene barrels or molasses puncjieons 
 answer admirably. Copiier sulphate or Bordeaux mixture should not be placed in iron 
 vessels because of their corrosive action on that metal. Wood, brass, copper and 
 earthenware are safe to use. 
 
 (a) Stock Solution of Copper Sulphate. 
 
 ITave on hand at least two barrels or puncheons, and, assuming that one of them 
 will hold so much, fill it with 60 gallons of water. Tie up CO pounds of copper sul- 
 phate in a hag or a piece of canvas and suspend it just beneath the surface of the 
 water until it dissolves. There will then be one pound of copper sulphate in every 
 gallon of the liquid, and for every pound required it will be only necessary to measure 
 out a gallon. Cover the barrel to iwevent evaporation. 
 
i:i 
 
 (b) Stock Milk of Lime. 
 
 Pinor r.O pounds (nbout two-thirds „f „ bushol) of .,uicklin.P into the otl.or l.arrcl 
 and slake ,t ^rndunll,-. Be ...r.,ful „ot to "drown" it. When it ha. all erumbled. stir it 
 op w,th water into „ paste ,„,d then fill the barrel „p to the fifty gallon m„rk. A 
 gallon of th,s l„,uid tlierefore .-ontalns one pound of lime. Provide this vessel with 
 a eover also. 
 
 To make 40 prnllons of spra.v proceed as follows: Run W pnllons of water i.,to 
 the tank of the spraying, mn.-hine. add .; ^^allons of the sto,.k solution of eop,K>r sul- 
 I-hate and sfr well. Mi.x up the sto..k milk of lime thorou^^hly and draw off four 
 gaIlon.s. runn.np ,t throuKh a strainer to keep baek the eoarser parti.'les Then stir 
 up the eopper -ulphate in the spray tank ap.in. and whil,. stirrintr a.ld the lime Never 
 
 ni-.x the eon-entrat^Hl eopin-r sulphate soluti ,„d the .strong- milk of lin.e and dilute 
 
 att.Twards, beeau.se the spray mad.- in this way is not so gtmd 
 
 The eloudy blue li„uid whiel, results is Rordeuux mixture. It must not eontain 
 exeess of eop,H>r sulphate in proportion to lime, otherwi.se the foliape will U- burned 
 If the hme .s ,»,r/,- („ol a.r-shl.-,;}) „,„1 reasonably pure there is little .lander of this 
 happening, but the spray should always b.. tested with a solution made bv dissolving, 
 half an ounce of Massium ferroeyanide in half a pint of water. Add a drop or two 
 of tins to spray and if the Bordeaux turns distinctly brown where the drop strikes 
 more lime is needed. 
 
 The poison for the Colorado be..tle may be applies! alon^^ with the Bordeaux as 
 o ten as may be necessary. Either Paris ,.reeii or arsenate of lea.I. or a combination 
 of both, may be used. Arsenate of lead sticks better but the other is cpiieker in -iction 
 so that It is safer to u.se both. Half a pound of Pari, (rn-en and a ,«,und a.,,1 a b ,lf 
 of lead arsenate to 40 gallons of spray will prove effw-tive in most cases nnlc. the 
 attack IS verj- severe, in which case these quantities should be increased by a half