. Bacteria in relation to plant diseases. Bacteria; Plant diseases. WILT-DISEASES OF TOBACCO. 229 only recently diseased. Nothing resembling the Bacillus nicotianae Uyeda or the large micrococcus of van Breda de Haan was observed. Only a few of the many plants received from North Carolina were used for making poured plates. The foliage was removed from the remainder and the plants (most of which were in early stages of the disease) were then set out in a hothouse belonging to the U. S. Department of Agriculture, and carefully watched. For some weeks they showed no further indications of diseas
. Bacteria in relation to plant diseases. Bacteria; Plant diseases. WILT-DISEASES OF TOBACCO. 229 only recently diseased. Nothing resembling the Bacillus nicotianae Uyeda or the large micrococcus of van Breda de Haan was observed. Only a few of the many plants received from North Carolina were used for making poured plates. The foliage was removed from the remainder and the plants (most of which were in early stages of the disease) were then set out in a hothouse belonging to the U. S. Department of Agriculture, and carefully watched. For some weeks they showed no further indications of disease. They rooted readily and made new leaves. Afterwards all of these plants developed further signs of wilting (Vol. I, pi. 27, left fig.) and finally perished of this disease, the pith being rotted out as in the Sumatran disease. The vascular ring in these plants was stained dark brown or black, and the parenchyma was also blackened in places, both in the interior and on the surface of the green stems. In some instances cracks or cavities ap- peared on the surface, opening into the depths of the stem, and the tissues in and around these fissures were blackened. The bacteria were present in the diseased tissues in enormous numbers. When the plants had died they were removed and healthy tobacco plants grown from seed sown in the Department houses were set in their place. These plants were some months old and naturally the root-system was wounded considerably in transplanting them. To the writer's surprise all of these plants (a dozen or more) contracted the disease within a few weeks and finally died of it. The checks left in the other house remained free from the disease. Starting with single colonies of the North Carolina organism obtained from the Petri-dish poured plates, subcultures were made, and from these subcultures healthy tobacco plants in another house were inocu- lated in considerable numbers by needle-punctures in the stem or leaf. These plants readily contracted th
Size: 1089px × 2294px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherwashingtoncarnegie
