Diseases of plants induced by Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae diseasesofplant00tube Year: 1897 PERIDERMIUM. 413 branch, the living jDortions of the ring grow on with increased vigour, and even attempt to close over the injured portion. This irregular growth, continued in many cases for years, pro- duces abnormal cross-sections (Fig. 248). The mycelium grows out centrifugally from diseased spots, so that the wounds continue to enlarge, and the disease becomes easily noticeable on account of the
Diseases of plants induced by Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae diseasesofplant00tube Year: 1897 PERIDERMIUM. 413 branch, the living jDortions of the ring grow on with increased vigour, and even attempt to close over the injured portion. This irregular growth, continued in many cases for years, pro- duces abnormal cross-sections (Fig. 248). The mycelium grows out centrifugally from diseased spots, so that the wounds continue to enlarge, and the disease becomes easily noticeable on account of the deep channels and distorted swellings on the pine branches and stems. As the disease spreads inwards into the stems, the conduction of water is interfered with and the branches above such wounds dry up and die oft'. AVhereas Fig. -247.—Pt,-id',-mlum p!ni (coiticolo). o, c. Mycelial stroma developed in the rind; the have become isolated from each other and contain haustoria, h, of the fungus. /-, Basidia composed of much smaller cells than in the needle-inhabiting aecidia. ;<, The peridium. (After R. Hartig.) young plants soon succumb to attack, the struggle with old trees may go on for years. Fresh infection of older stems occurs generally in the higher parts of the tree, where the bark is still thin. Pycnidia (spermogonia) are developed between the rind- parenchyma (periderm) and cork, generally towards the margin of diseased spots. The conidia emerge from the ruptured cork-layers of the bark as a honey-sweet liquid. H. Mayr states that this liquid is given off in such quantity from species of Pcridermium in Japan, that it is collected and eaten bv the natives.
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