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 120 I'HYCUMVCKTES. tufts, and form a white border round the brown parts of the leaf; they are monopodially branched and produce terminal sporangia (gonidia), which are easily detached. The sporangia on germination either pro- duce a varying number of zoospores, or germinate directly like conidia to form a mycelium capable of pro- ducing new conidia. The potato-disease is distin- guished from Fhytoihth
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 120 I'HYCUMVCKTES. tufts, and form a white border round the brown parts of the leaf; they are monopodially branched and produce terminal sporangia (gonidia), which are easily detached. The sporangia on germination either pro- duce a varying number of zoospores, or germinate directly like conidia to form a mycelium capable of pro- ducing new conidia. The potato-disease is distin- guished from Fhytoihthora omnivora in the absence of sexual reproduction by oospores.' It is generally assumed that the mycelium hibernates in potato-tubers, from which the fungus recommences to spread in spring. Boehm, however, contests this, and holds the hibernation of the fungus to be quite unknown, and that from the tubers of Fig. 31.âSurface of a Beech-seedling with swarm- ;i disCaSCd plaut, either a spores a, h; the gerin-tubes from these penetrate ' between adjacent epidermal cells; c, sporangivmi with healtllY plant Or llOUC at zoospores already germinating inside it, </, /'; c, a 1 germ-tube which lias penetrated directly into an -W reSUltS. epidermal cell; g, germ-tube which, after growing Aft *'?'L'*.' ' <=eU, has again made its way out. TllC PliytoplltJlOra potatO- disease is quite distinct from {a) the potato-blight or wet-rot which, according to Boehm, is the result of closing up of the lenticels, with a consequent stoppage of respiration; (??) bacteriosis, which will be considered amongst the bacterial diseases of plants. Lagerheim has pointed out that Solanum muricatum much cultivated in Ecuador on account of its edible fruit, has been for many years subject to attack from Phytophthora infcstans; the fruits sicken and rot off before ripening. The This is a well-known point of controversy, for an interesting discussion of which we would refer to ''Diseases of crops,' Worth. G
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