Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . thatthe agency chiefly concerned is a low form of fungus —one of the slime-molds—the vegetative portion of whichdoes not even develop mycelium threads, but grows as asemi-liquid slimy mass. This gains access to the tissuesof the young roots and develops in the cells, causing thetissues to become malformed in various ways. Afterdeveloping in this way awhile the mold produces innu-merable spores, w^hich are set free by the rotting of theroot tissue, and left
Fungi and fungicides; a practical manual, concerning the fungous diseases of cultivated plants and the means of preventing their ravages . thatthe agency chiefly concerned is a low form of fungus —one of the slime-molds—the vegetative portion of whichdoes not even develop mycelium threads, but grows as asemi-liquid slimy mass. This gains access to the tissuesof the young roots and develops in the cells, causing thetissues to become malformed in various ways. Afterdeveloping in this way awhile the mold produces innu-merable spores, w^hich are set free by the rotting of theroot tissue, and left in the soil. Here they germinateby the production of zoospores, which remain in thesoil apparently indefinitely, and penetrate—when oppor-tunity offers—the thin-walled cells of roots and rootlets,thus continuino: the cvcle of existence. The disease commonly attacks seedlings in the seedbed. Such plants begin an abnormal root-development, 138 \ - THE CLUB ROOT 139 a few roots becoming greatly swollen, as shown in , and the leaves, instead of having the dark greencolor of healthy foliage, become pale green or FIG. 57. CLUB ROOT OF OABBAiJK. Sujch an injury, of course, prevents the proper develop-ment of the plant, which becomes worthless. The injury to other crops than cabbage is oftensevere. Cauliflower is frequently attacked with fatal,effect, as may be seen in the photo-reprorlnction in Fig. 140 FUNGI AND FUNGICIDES 58, while turnips commonly suffer in a most disastrousmanner (Fig. 59). But cultiyated crops are not the onlyhosts of the fungus—a fact which makes it still more
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectpathoge, bookyear1896
