. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 261 possesses an Alternaria conidial form. Following Diedicke, the forms given below would be recognized. P. bromi Died. Perithecia brown, hairy; asci 189-288 x 34-59 n, saccate, thin- walled; spores 2-seriate, golden-brown, 4-celled, 48-83 x 19-33 n. Conidia (=Helminthosporium bromi) on brownish spots, 108- 150 X 13-20 li, 5 to 7-celled, dark colored. On Bromus. P. gramineum Died. Conidia (=Helminthosporium gramineum); conidiophores short, subflexuose, light-brown; conidia solitary, elongate-cyl
. The fungi which cause plant disease . Plant diseases; Fungi. THE FUNGI WHICH CAUSE PLANT DISEASE 261 possesses an Alternaria conidial form. Following Diedicke, the forms given below would be recognized. P. bromi Died. Perithecia brown, hairy; asci 189-288 x 34-59 n, saccate, thin- walled; spores 2-seriate, golden-brown, 4-celled, 48-83 x 19-33 n. Conidia (=Helminthosporium bromi) on brownish spots, 108- 150 X 13-20 li, 5 to 7-celled, dark colored. On Bromus. P. gramineum Died. Conidia (=Helminthosporium gramineum); conidiophores short, subflexuose, light-brown; conidia solitary, elongate-cylindric, 4 to 7-celled, 15-19 n wide and of variable length. The mycelium invades the tissue -causing long brown spots. These later become covered with an abundance of conidiophores which emerge through the stomata. Potter also reports in- vasion and complete occupation of ovaries by the mycelium. Sclerotia-like bodies are formed on leaves and stems. They were first seen in artificial cul- tures of the fungus by Ravn '^"â ^ and have been since found in nature (Noack 24^). The conidiospores have been shown to be long-lived, and spring infection begins largely from conidia carried over winter on seed. Extensive study was made of the conidial form by Ravn who found the mycelium to be of two kinds, one afirial and hyaline, the other strict and dark. It grew well on acid or neutral media. Careful infection experiments (Ravn) proved the pathogenicity of H. graminum for barley but showed it incapable of infecting oats, rye or wheat. Ravn regards the disease produced by H. gramineum as often general, not local, in that the mycelium may invade the growing points, resulting in infection of all the Fig. 192.âP. trichostoma. 1, group of asci, 2, a single spore at the apex of an ascus. After 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 ma
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectfungi, bookyear1913
