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Show M,MM,Mi,aMaaiBaaajaiaMaBaaiMaaaaMiaaafaiaMh THE POTATO SCAB. A Disease Always Accompanied by is Tor lloular Funffiia. In tho annual report of the Connecticut Connecti-cut experiment stntlon for 1800, Dr. Uolnnd Thnxtcr (fives an Intcresllnrf account of his experiments with potato "scab." Tho followlnff synopsis li mado from his report tho pictures shown being copies of tho original ones used: Almost everybody who has raised "scabby" potatoes has somo theory ns to tho unuso of the disease. Somo claim that It Is caused by oxccsslvo moisture In tho soil, others think It Is produced by Irritation brought about by sul-stances sul-stances of Inbccts In thu r.oll that ccratch or mar tho tubcr3, still others think it is a result of chemical nctlon duo to tho presence of llmo or oxido of Iron In tho soil, whllo another theory Is that stnblo manure Induces the disease. dis-ease. Tho troublo about nil these theories Is that perfectly hciilthy pota toes aro frequently produced In wet soils nnd with stable manure, whllo tcab frequently occurs on light, dry land. Dr. Thaxtcr thus dismisses tho Insect-catlno: theory: "Turning to tho thcorlos which connect tho 'scab' with tho nctlon of somo organism, vegetable fu..t ila llnunnl' (linrm In fiun very commonly entertained, pspoclally by farmers, 'Inscctft Including earth && , V $&$$&& Tin, 1. BI'Et'tMBN OV OIIIII.NAIIY "l)EI'" , I'OTATO BCA1I. worms. Thin Idea ii based upon the fact that senb spots form an nttructlvo feeding rrround for u variety of Injects, especially wlrc-woruis, myrlupods nnd inltcs; tho common occurrcuco of which, cspechilly In tho deeper scab spots, bus led to th belief that tlr. two wero directly nssoclalcxl. That this Is not tho case, has been shown by careful observation, tho only connection be-tweon be-tweon tho two resting on tho fact that tho injury already existing from n qulto different cau'.o la often extended by them very considerably." Tho earliest Iwtanicnl explanation of tha cau.o of scab was In 183 when Dr. Wallroth attributed It to tho a.llon of a certain fungus. It has slnco been shown that this was another dUcaso ontlrely, ami only In recent years has tho true dlseaso been carefully studied. Without going Into n detailed account of Dr. Thaxter's experiments of interest in-terest mainly to Iwtanlsts or giving a description of tho dlscnsc, which li familiar fa-miliar to nil who cat potatoes, wo may :w that exnoriments wero mado tc learn If tho dlscaso could bo transmitted by infection, HUo smallpox or menslcs In n human subject. It has been proved that It can. At Fig. 1 Is a photograph pho-tograph of a scabby potato as It was tauen from tho soli. As these scabby potatoes grew in tho field, tho mlcro-scopo mlcro-scopo detected a grayish 111m in rWinec-tlon rWinec-tlon with scab spots, and this sub-stanco sub-stanco was taken for inoculation. Potatoes Po-tatoes In half a dozen or more hills were Infected with tho disease. Tho tubers wero uncovered hud lightly touched with a necdlo that had been no. a. "deep" bCAii, iNiiuccn nv in OCIU.ATIO.V, IV FOKJI OF MO.N001t.lM It. T. dipped in thu diseased substance obtained ob-tained from scabby tubers. In every case, within thrco days, tho point touched by tho necdlo showed symptoms symp-toms of tho disease, and Mtb&cquoutly developed Into oca lis. This wns not considered n fair test, as potatoes in neighboring hills wero afterwards found "diseased, so nuother test was mado with potatoes growing in a greenhouse. Ono or mora potatoes In each of 18 small hills wero Inoculntcd with tho disease. In every enso but ono they liecamo "Hcabby." At Tig. S is shown n photograph of ono of these potatoes. Tbo lcttura "It. T." wero traced with tho necdlo bearing tho disease dis-ease Peo how closely tho scab has fob lowed It Thero wero 8 tubers left unaffected. unaf-fected. Of theko 31 wero qnllo clean, whllo five showed ono to several tcab mar'.ss only threo of which wero nf-fected nf-fected in the soil. The substance of tho matter Is that Dr. Thaxter concludes that tho "ivcab" dlsenso U always accompanied by n particular fungus. What it is und iiow to prevent It uro raattort. that havi not yet .won dotorralnoJ. Wo nra just bo-(jlnnlng bo-(jlnnlng to undarttand tho dlbea:.o. Let ua remember that for centuries doctors wero In tho darh rospecting human diseases dis-eases which aro now perfectly well tin dcrstnod. Lot un hop that thij ceub dlscaso will le cccurately dctei mined, and that a remedy for it may ha found rratleast that wo may Uaow how to ovoid tho coudltlona mos.t favorable fur Its development -ltural New Yorker |