. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 311 only three are of economic importance. By Engler and Prantl, the genus is not separated from Ustilago. Sphacelotheca sorghi (Lk.) Cl.^'- ^^ ^^s, m, 144 Sori usually in the ovaries or stamens forming oblong to ovate bodies 3-12 mm. in length (rarely fusing the very young spikelets into irregular forms), protected for some time by a false membrane upon the rupture of which the olive-brown spore-mass becomes scattered, leaving naked the dis- tinct columella of plant tissue. The sterile cells of
. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 311 only three are of economic importance. By Engler and Prantl, the genus is not separated from Ustilago. Sphacelotheca sorghi (Lk.) Cl.^'- ^^ ^^s, m, 144 Sori usually in the ovaries or stamens forming oblong to ovate bodies 3-12 mm. in length (rarely fusing the very young spikelets into irregular forms), protected for some time by a false membrane upon the rupture of which the olive-brown spore-mass becomes scattered, leaving naked the dis- tinct columella of plant tissue. The sterile cells of the membrane break up to some extent into groups, hyaline, oblong to sub- spherical, chiefly 7-18 /x in length; spores subspherical to spherical, smooth, contents often granular, — fi in diameter. On Johnson grass and sorghum throughout the world. The young pistil and usually the stamens as well are displaced by the fungous mycelium, the two being often blended together. The spores ger- minate readily in water, either when fresh or a year old, showing papillae in from three to ten hours. The promycelium is 2 to 3-septate and from the ends of one or more of its cells narrow tubes appear. These later fuse with the adjacent cell, forming the «'buckle ; Either infection tubes or sporidia may also arise from the promycelium. Infection is possible only with young plants. The mycelium in the host plant grows rapidly into long irregu- lar, hyaline, thin-walled threads 2-4 mm. thick, which run through and between the cells. It is most abundant in the parenchyma, advancing especially through the pith region with the growth of the host. The young ovaries and stamens are eventually reached. Fig. 225.—S. sorghi, cross-section through base of young infected body (ovary), a, false membrane of epidermal cells and sterile'my- celium, 6, mature spores, b', im- mature spores, c, columella. After Please note that these images are extracted from scanned page images
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1913
