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Tous las autras axamplairaa originaux sont filmAs an commanfant par la pramlAra paga qui comporta una amprainta d'imprassion ou d'iiiutuation at an tarminant par la darnlAra paga qui comporta una talla amprainta. Un das symbolas suivanta apparattra sur la darniAra imaga da chaqua microficha, salon la caa: la symbols — ^ signifia "A SUIVRE". la symbols Y signifia "FIN". Laa cartaa, planchas, tablaaux, ate, pauvant Atra fiimAa A daa taux da rAduction diff Arants. Lorsqua la documant ast trop grand pour Atra raproduit w un saui clicliA, II ast filmA A partir da I'angia supAriaur gaucha, da gaucha A droita, at da haut an baa, an pranant la nombra d'imagaa nAcassaira. Laa diagrammaa suivanta illustrant la mAthoda. 2 3 5 6 • ^f f^ DOMINION OF CANADA Department of Agriculture Experimental Farms J. H. CWSDAU. ■ Alt.. {Nrghe,t n»rke. prtce. There .« two p....o *..«.. «hi.h 'if'ff^^'^Jl^^'^t^j^'S^S^Sk'tL'Z i„, potato.. I«r " '"''f P''l""°i'»r' »:"Lt whfcM^^^ U n.c«..r,. The ?.'cCd'?.'l-OwiERY"'sCAB*C'fi^ 4'rd'4:), . Le^ -".«'» •'»--«' »" ">• Continent of America. • r J Under the Destructive Insect and Pest Act of Canada, atiy person using lor seed Dotat«"tlSedbyKto anker or POWDERY SCAB is table to P'OS«ut'°n. potatoes inteclea y ; j^t; ,„ ,1,^ ,„» diseases; any ca«! of Potato anker -shouldTuch be foSnd anywhereAr Powdery Scab, which already occur, .n s«ne ^t,™ the D«^inion. musl be reported imnrediately to the Dominion Bolani^. Ex- ?:;imenurFarm. Ottawa Potato 8'owe» «e «que.ed to^^^^^^^^ leial Droccpdings against the person having failed to report tiiem. ' Thrdi^as^ are'to be reputed ,0 the Dominion Botariis. in order jhaM^e^ Erw::^oT;heSD'o= To& ferS'^ttt tre"4 r t meit of c^Ti^wn to'^them, and by closely following the instructions whic 1 *" ''ifin doubt as to the fitness of potatoes for use as seed, send a sample to the p<> mini» BoS (^«° free if below^ lb. in weight), who will advise you by return mail. «^-,« POTATO DISEASES TBABSHITTED BY THE USE OF UNSOUMD POTATOES The coloured chart shows a number of potatoes affected by fundus diseases, and blemished which are not diseases, but which it is not advisable to use For seed. '^^^y,p ■ome yeart it is difficult to aecurc seed pot«lo« Jree from either d»ea.e. Seed treatment » recom- mended {or thete two trouble.. Soak the tubera for three hourt in a 1 : 2000 •ol. of bichloride of mercury (corroMve aubliroale) or in I lb. formalin in 30 Imperial gallon* of water, i he tormer chemi- cal ia highly poiK>noua and will corrode iron veMela— hence u^ wooden barrel* or tubt--tlie latter is distiiKtly pungent and irritating to the skin, though not a serious poison. None of the following Diseases can be Controlled by Seed Treatment Figs. 4 and 4« ivprMwit the appeMruic* of POWDERY SCAB. This disMse U con- sidM^so swious by Um Unit«d States •uthoilU.s that thw placed an •mbargo on all po- tatoes from countries where this disease exUted. This included the Dommioii of Canada. ThU disease resembles Common Scab (Fig. 8). but U in reality more serious, parttctdarhr when potatoes affected with Powdery Scab are planted year after year on the same land, when the disease may assume a serious nature and produce a crop hardly worth harvestmg. Where Cases of this Disease han occvrred, Change Year Seed and Plant on New Land It would be unwise to pick out apparently sound potatoes from a diseased crop, as the in- itial stages of the disease may not be vUible externally. Thews are the only precautions which will rid the country at the earliest date possible of this disease. Every case of thu disease must be reported to the Dominion Botanist. Farmers should bear m muid the conse- quences of not reporting cases of this disease. Fig. 5. A tuber infected with POTATO CANKER. Another disease that must be re- ported immediately, should any case be found to occur in Canada. It is a serious potato dis- ease. All importations of potatoes into Canada from Europe and other countries are pro- hibited because of the prevalence of this disease in those territories. Thu precaution had to be taken as a temporary measure, because if Potato Canker should be found to occur m Canada, thu would be another reason for an embargo on Canadian potatoes. (See also Farmers' circular No. 3 entitled POTATO CANKER DANGER.) Figs. 6 and 6a illustrate common "Dry Rot." This forn' of disease is most common among stored potatoes in bins, pits or cellars. Whitish funaus or mouldy urowths appear on the outside of a shruri; ken. dry. hard skin. The inside consists of a dry, powdery, discoloured substance. Another storage rot is the "Wet Rot" in which the potato is reduced to a soft, decaying mass, giving off a putnd odour. Both diseases render tubers totally unfit for use as • seed. tc i jo Fig. 7. Some potatoes may appear quite sound externally (see also descriptions of hgs. I and ^) but when cut at the "stem" end. a brownish-black ring or discoloured area just below the skin, may become noticed; this discolouration will disappear frequently on cutting away slices towards the "eye" end. This is a disease known as "Stem End Rot. In severe -les the discolouration area will be diffused through the whole interior of the potato. Potatoes sik wing this disease will tre- quendy rot in the ground when planted. They are quite useless for seed purposes. Fig. 8. Common Potato Scf\b (See under Fig. 2.) tl i Fias. 9 and 9a illustrate a disease very widely known in potato growing countries. They show potatoes affected with "Late Blight." Externally this disease is visible bv the darker brown sunken- in portions of the skin. When cutting into these spots the "flesh u. Wath will show "regular brownish spots permeating the interior. Such potatoes are unfit for seed ourposes. It is probable that the destructive epidemics of Late Blight in the standing crop originate from the planting ot such *^*' These are the commonest diseases of potatoes transmitted by the "seed tubers." Note the im- portance of at once reporting any cases of Potato Canker or Powdery Scab. Prompt action only will avert serious damage. The sooner Powdery Scab u wiped out the better. 1 hu should be the aim of all Canadian potato arowers. This result can be brought about only by the use of sound seed potatoes planted on suitable soil that has not previously produced a diseased potato crop. Re-appearance of powdery scab in potatoes is an indicatiorj that the grower has been neglectful in the choice of his seed potatoes or his land. The neglect of one may be a detri- ment to a whole community or a whole county. i i j The Dominion Botanist. Central Experimental Farm, Ottawa, to whom letters and parcels under five pounds in weight may be addressed free of postage, will be very glad to assist farmers m all matters of diseased vegetation. It is important to communicate any trouble m time and not allow it to become serious before seeking advice, when it is often too late to be of service. H. T. GUSSOW, April, 1914. 'ii-Kf Dominion BotanUt. r