The Granville tobacco wilt / by Erwin F. Smith.

  • Smith, Erwin F. (Erwin Frink), 1854-1927.
Date:
1908
Catalogue details

Licence: In copyright

Credit: The Granville tobacco wilt / by Erwin F. Smith. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    SPECIFIC GERM INVOLVED. The cultural characters of the tobacco organism are the same as those of liacterhuu solatiaceftnini derived from tomato or potato, and now that good cross-infections have been obtained no doubt remains that the (iranville wilt of tobacco and the brown-rot of potato, tomato, and eggplant are one and the same disease, i. e., due to the same organism, all of these plants belonging to the nightshade family and being rather close relatives. The Florida tobacco wilt at Quincy and Hinson appears to be the same thing. I examined diseased plants from Florida some years ago and again this year. ^ The writer formerly stated (1896) that he did not succeed in cross- inoculating Barfn-imil snlaiiacearmii into tobacco and peppers, and at that time he believed tobacco to be exempt, but not many experiments were made, and we may assume either that the cultures used had lost their virulence or that the particular plants selected were too old or growing too slowly, or for some other reason were unusually resistant. The writer now believes that Bacferimii solaiiareannii does frequently lose its virulence by continued culture; that, in general, old and slow- ■ growing plants are diHicult to infect; and that some individuals and some varieties are more resistant than others. This, I believe, sulli- i ciently explains the former failures. We may conclude, therefore, in searching for remedies that we have one disease to deal with and not ', several. METHOD OF ENTRANCE OF THE BACTERIUM. j ■ ' If stomatal infections occur, which is not unlikely, especially in wet j' weather, thev have not vet been demonstrated. So far as we know, '• ' this organism enters the i)lant onli’ through wounds. Van Breda de [ * Ilaan found the root system especially subject. Stevens and Sackett > state that the infection is first in the root. A large number of infec- * tions undoubtedly take place under ground, the organism present in ^ the soil entering the plant through wounds made in transplanting or J cultivating, or by small animals infesting the soil. Boots broken in . transplanting and leaves pulled or pinched off at that time are respon- } sible for many infections, and it would seem that b}’ care the number | of such wounds inviting infection might be greatly reduced. It has been observed in Sumatra, where occurs a destructive bacte- rial wilt some years ago identified bj- Hunger as due to Barferimii soituiacearmii, that the tobacco plants are peculiarl}’ subject to it when grown on land infested with eelworms (nematodes) or with insects which attack the roots or base of the stems. Rainy weather is favor- able to the progress of this disease, although the wilt maj’ be detected first in dry weather. In this country it has been observed, especiall}’ , by Earle on tomatoes in Alabama, that wet soil is peculiarly favorable to the spread of this disease. All observers agree tb.at the root system Hl-ll