. Bulletin. Natural history; Natural history. Aug, 1974 BoEN: Root Infection ^VITH V. albo-atnim 221 variably penetrated the endodermis and vessel members. The fungus grew to the endodemial layer within 4 days. The quantity of vessel meml^ers in- vaded appeared related to the number of points of entry and to the mass of mycelia that developed from the points of entry. The hyphae that penetrated the en- dodermis usually penetrated the vessel members through pits. The hypha nar- rowed to a thin, peg-like projection as it grew through the pit. Hyphae did not necessarily stop at the first vessel m
. Bulletin. Natural history; Natural history. Aug, 1974 BoEN: Root Infection ^VITH V. albo-atnim 221 variably penetrated the endodermis and vessel members. The fungus grew to the endodemial layer within 4 days. The quantity of vessel meml^ers in- vaded appeared related to the number of points of entry and to the mass of mycelia that developed from the points of entry. The hyphae that penetrated the en- dodermis usually penetrated the vessel members through pits. The hypha nar- rowed to a thin, peg-like projection as it grew through the pit. Hyphae did not necessarily stop at the first vessel member contacted, but in many in- stances they grew out through a pit on the wall of the vessel into an ad- jacent vessel on the side opposite the entry point (Fig. 5). The mycelium was generally unbranched, hyaline, in width. No typical conidiophores were observed. VerticiUium conidia were observed in the xylem 8 days after inoculation. In most cases, the conidia appeared to be free-floating in the xylem stream and in no way connected with the mycelium present (Fig. 6 and 7). The conidia often were found lodged at the end walls of the vessel members (Fig. 8). No defense mechanism such as tyloses or gimi deposits was observed in the xylem members. The lack of a defense mechanism on susceptible hosts is in complete disagreement with other workers' data on hops and cotton (Table 4). Penetration of Vascular Region of Resistant Hosts Altliough the fungus penetrated the cortical cells, few hyphae penetrated the endodermis and vessel members. The quantity of vessel members in-. Fig. 5.—Longitudinal section through the vascular cylinder of redbud showing a hypha vithin a vessel member (X 850).. 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 Illinois. Natural History Survey Division. Urbana, State of Illinoi
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Keywords: ., booka, bookcentury1900, bookdecade1910, booksubjectnaturalhistory
