. Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae. Plant diseases; Parasitic plants; Fungi. 186 ASCOMYCKTKS. The (lark-red masses of thick-coated, warty perithecia appear in autumn and winter on the dead branches only; the asci contain eight bicellular hyaline spores which germinate directly to form a mycelium. Infection of a new host-plant is eftected by the mycelium, which enters by open wounds into living branches; it is quite unable to penetrate the living bark and is dependent on wounds. The mycelium sp
. Diseases of plants induced by cryptogamic parasites; introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae. Plant diseases; Parasitic plants; Fungi. 186 ASCOMYCKTKS. The (lark-red masses of thick-coated, warty perithecia appear in autumn and winter on the dead branches only; the asci contain eight bicellular hyaline spores which germinate directly to form a mycelium. Infection of a new host-plant is eftected by the mycelium, which enters by open wounds into living branches; it is quite unable to penetrate the living bark and is dependent on wounds. The mycelium spreads rapidly through the tissues of the host, especially through the vessels of the wood ; the cam- bium and rind are not attacked directly, but are killed in conse- quence of the destruction of the wood.^ The regions attacked in the wood appear as greenish stripes, and withering of leaves, followed by death of Ijrancli after branch, results in conse- quence of the growth of mycelium in the water-conducting elements of the wood. For protection against this and all other parasites, which find entrance by wounds, it is recommended to prune or dress trees only when necessary, and to paint all wounds with tar or tree-wax. This Nrdrin is one of the commonest parasites of our parks and fruit gardens, hence all branches already attacked should be removed and burned, likewise all blown timber which might serve as a nursery for production of spores or conidia. Nectria ditissima Tul. (J'.ritain and U.^. America). This is a conmion parasite and a frequent cause of the canker of beech, apple, and other trees.^ The mycelium lives chiefly in the bark, causing it to die and form cracks. Under ordinary conditions all cracks and fissures are occluded or. Fig. 79.—Nectno. cinnaMar section of perithecial colony ascospores. (After Tulasne.) 0. Knlarged Uei-hiinatiiig ' Mayr in Hartig's UnltrsnchuiKjm a. d. forst-hotan. Iiistiiut :.n Munchen, in. Berlin, 1882. Brick, Arheiten d. botan.
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