. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. 342 BACTERIA IN RELATION TO PLANT DISEASES The new varieties are also cataloged by one of the growers, and of these 7 are marked as much subject and 6 as very resistant, while 31 do not fall into either class. Wakker states that most of the leaf-infections are usually observed in the fields in the month of May, but thinks that infection must take place at least a month earlier. The writer's experiments have led him to the same conclusion. Undoubtedly the bulk of the field infections occurs during blooming time, when insect
. Bacteria in relation to plant diseases. Bacteriology; Plant diseases. 342 BACTERIA IN RELATION TO PLANT DISEASES The new varieties are also cataloged by one of the growers, and of these 7 are marked as much subject and 6 as very resistant, while 31 do not fall into either class. Wakker states that most of the leaf-infections are usually observed in the fields in the month of May, but thinks that infection must take place at least a month earlier. The writer's experiments have led him to the same conclusion. Undoubtedly the bulk of the field infections occurs during blooming time, when insects would be visiting the blossoms freely. The downward movement of the disease in the leaves is very slow (Wakker, Smith).. Fig. ]35*. Fig. 134.* MORBID ANATOMY. There are no hyperplasias in connection with this disease. It is primarily, and to a considerable extent during its whole progress, a disease of the vascular bundles. The reasons for this the writer has attempted to set forth in his papers on this organism (see Literature). They are noted briefly under the next head. The xylem portion of the bundle is the first part to be attacked, especially the spiral vessels which are soon filled entirely by the rapid multiphcation of the organism (plate 20, fig. 6). This is what causes the bright *Fio. 134.—Cross-section of base of a hyacinth bulb, showing cavities in parenchyma due to Bad, hyacinlhi. Upper part of drawing is extreme base of a bulb scale; lower is part of plateau. Starch grains are represented in outline only. Slide 502 A—A3, from plant No. 67 inoculated in the flowers (see Bull. 26, p. 30). *FiG. —Bad. hyacinthi: A detail from fig. 134 at Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Smith, Erwin F. (Erwin Frink), 1854-1927. Washington, D. C. , Carnegie Institution of Washington
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