Identifier: fungousdiseases00dugg (find matches)
Title: Fungous diseases of plants, with chapters on physiology, culture methods and technique
Year: 1909 (1900s)
Authors: Duggar, Benjamin M. (Benjamin Minge), 1872-1956
Subjects: Fungi in agriculture Fungi Plant diseases
Publisher: Boston, New York (etc.) : Ginn and company
Contributing Library: University of British Columbia Library
Digitizing Sponsor: University of British Columbia Library

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t; B, control, healthy Subsequently the disease passes out again from the infected steminto healthy leaves and up into the center of the head. If leavesdiseased at the edges are pulled off and examined where they jointhe stem, the groups of fibrovascular bundles, or leaf traces, in thepetiole, are seen to be either free from the disease, in the earlystage, or decidedly brown or even deep black from its presence.Leaves attacked in this manner fall off prematurely one afteranother, leaving in bad cases a more or less elongated stem cov-ered with leaf scars and crowned with a tuft of small leaves. Ifthe disease has entered the stem only on one side, that side isdwarfed and the head becomes one-sided. When young plants 1 Smith. The lilack Rot of the Cabbage, /. r., p. 6. SCHIZOMYCETES. BACTERIA 109 are affected they may be killed. Any affected plants are prey tosaprophytic organisms, and an offensive soft rot is then likely toresult. Whether in the leaves or in the stem, the course of the
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Fig. 24. A Cabbage Leaf with Black Rot developing from WaterPore Infections. (Photograph by F. C. Stewart and H. A. Harding) disease may usually be traced by a darkening of the fibrovascularbundles. Fig. 23 shows a healthy and a diseased plant, the latteras a result of artificial infection. Root infection may also occur. This disease has been found upon apparently all of the commonvarieties of cabbage, in regions where the organism has gained astrong foothold. Turnips, cauliflower, kale, rape, and other species I lO FUNGOUS DISEASES OF PLANTS of cultivated and wild cruciferous plants (such as mustard andcharlock) are also known to be susceptible. The organism, morphology and reactions. Upon gaining entrancethrough the water pores upon the margins of leaves this organismmultiplies enormously. It is probable that a cellulose enzyme isslowly secreted, for in time masses of bacteria cause the progress-ive disappearance of the cell w^all in contact with them. Throughthe vessels of the fibr

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