. Fungous diseases of plants, with chapters on physiology, culture methods and technique . make its appearance in the springand the last to disappear in winter. Evidently, it is not readilyaffected by minor climatic differences, and probably slight dewsare sufficient to insure its propagation. This fungus is most common upon the forms of the ubiqui-tous shepherds purse {Capsella Bnrsa-pastoris) ; but it is alsocommon upon the radish {Raphaiuis sativjis), horse radish{Cocklearia Armoracia), cress {Brassica oleracea), turnip {Bras-sica Rapa), mustard {Brassica nigra), water cress {Radicida Xas-t
. Fungous diseases of plants, with chapters on physiology, culture methods and technique . make its appearance in the springand the last to disappear in winter. Evidently, it is not readilyaffected by minor climatic differences, and probably slight dewsare sufficient to insure its propagation. This fungus is most common upon the forms of the ubiqui-tous shepherds purse {Capsella Bnrsa-pastoris) ; but it is alsocommon upon the radish {Raphaiuis sativjis), horse radish{Cocklearia Armoracia), cress {Brassica oleracea), turnip {Bras-sica Rapa), mustard {Brassica nigra), water cress {Radicida Xas-ttirtitim-aquatic?nn), etc. I50 FUNGOUS DISEASES OF PLANTS Symptoms. The effects of the fungus are somewhat variousupon the different hosts. Upon the shepherds purse the stemsare enlarged and distorted, while no unusual malformations offloral organs and leaves generally occur. On the radish the floralorgans may be strikingly hypertrophied (Fig. 49), ovary sacsgreatly enlarged, stamens, petals, and sepals distended and some-times becoming leaf-like. Upon nearly all hosts the porcelaneous. Fig. 50. CoNiDiAL Stage, Fertilization, and GerminatingOospore of Cystopus. {b and c, after De Bary) conidial cushions, characteristic of the family to which this speciesbelongs, are prominent. The fungus. The conidial cushions occur upon leaves, stems,and floral parts, or fruits. On the majority of hosts, such asshepherds purse, horse radish, etc., oospores generally occur onlyin the stems, yet upon some other hosts, particularly upon certainmustards in the western United States, oospores alone are com-mon. The mycelium is considerable, and constantly intercellular,with abundant knob-like haustoria. The mycelium develops abun-dantly at some points just beneath the epidermis, and there areproduced numerous short, erect, basally branched latter give nse to simple chains of spores in basipetal suc-cession. These are usually separated one from another by slight PHYCOMYCETES I^l \
Size: 1845px × 1355px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherbostonnewyorketcgi
