. Diseases of plants induced by cryptogamic parasites : introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae . Plant diseases; Parasitic plants; Fungi. PLASMOPARA. 129 the Vine. This parasite was introduced into Europe from America.^ It makes its appearance in early summer as white patches on the under surfaces of leaves, sometimes also on stalks and fruit. In the course of the summer the leaves show brown spots and dry up. The white patches consist of tufts of branched conidiophores, from which ovoid conidia are abjointed. These on germina-. FiG. 40.—Ptasmopara vi
. Diseases of plants induced by cryptogamic parasites : introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae . Plant diseases; Parasitic plants; Fungi. PLASMOPARA. 129 the Vine. This parasite was introduced into Europe from America.^ It makes its appearance in early summer as white patches on the under surfaces of leaves, sometimes also on stalks and fruit. In the course of the summer the leaves show brown spots and dry up. The white patches consist of tufts of branched conidiophores, from which ovoid conidia are abjointed. These on germina-. FiG. 40.—Ptasmopara viticola. Conidiophores, much enlarged, (v. Tubeuf deL) tion in rain-drops discharge six to eight swarming cells from which germ-tubes grow into the epidermis of the host-plant; thus the disease spreads rapidly during moist weather and a Peronospora viticola, 1890. Magnus, Wittmack's Gartenzeit, 1883. Soribner, Report of Dept. of Agriculture for 1886, pp. 96-105; this contains an excellent account of this mildew. Articles on this subject dealing with remedial measures are frequently published in the Amer. Department reports and bulletins, in the bulletins from experimental stations, and in the horticultural journals. ^ Seymour and Farlow give it as occuring on every American species of Vitis. I. 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 Tubeuf, Karl, freiherr von, 1862-1941; Smith, William G. London ; New York [etc. ] : Longmans, Green & co.
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