. Diseases of plants induced by cryptogamuc parasites; introduction to the study of pathogenic fungi, slime-fungi, bacteria, and algae. English ed. by William G. Smith. Plant diseases; Parasitic plants. 120 PHYCOMYCETES. 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 P
. Diseases of plants induced by cryptogamuc parasites; introduction to the study of pathogenic fungi, slime-fungi, bacteria, and algae. English ed. by William G. Smith. Plant diseases; Parasitic plants. 120 PHYCOMYCETES. 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 Phytophthora 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.—Surface of a Beech-seedling with swarm- a disCaSCd plant, either a sjjores o, h; the germ-tubes from tliese penetrate ^ between adjacent ejiidermal cells ; c, sporangium with healthy plant Or nOUG at zoospores already germinating inside it, d, /; c, a J i: germ-tube which lias penetrated directly into an j^H reSUltS. epidermal cell; g, germ-tube which, after growing for a time inside a cell, has again made its way out. The PllvtOVhtllOra POtatO- (After R. Hartig.) "^ ,. , disease is quite distmct Irom (ft) 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; {h) 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 infestans; the fruits sicken and rot off before ripening. The ' Tliis is a well-known point of controversy, for an interesting discussion of wliich we wou
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectparasit, bookyear1897
