Fungous diseases of plants . merely small areas upon asingle leaf. In from ten to fifteen days after the appearance ofthe spermogonia the striking aecidial stage may be found appear-ing only on the lower surface of the leaf. The cushions whichproduce the spores are rapidly developed beneath the epidermis,and upon the rupture of the latter the bright orange spores aredisclosed. Eventually the under surfaces of the leaves may ap-pear to be covered with a continuous mass of more or less adhe-sive orange-red material. All of the vegetative parts of the plantwhich are affected are usually greatly i
Fungous diseases of plants . merely small areas upon asingle leaf. In from ten to fifteen days after the appearance ofthe spermogonia the striking aecidial stage may be found appear-ing only on the lower surface of the leaf. The cushions whichproduce the spores are rapidly developed beneath the epidermis,and upon the rupture of the latter the bright orange spores aredisclosed. Eventually the under surfaces of the leaves may ap-pear to be covered with a continuous mass of more or less adhe-sive orange-red material. All of the vegetative parts of the plantwhich are affected are usually greatly impaired in vitality and 428 FUNGOUS DISEASES OF PLANTS frequently appear spindling from the beginning. Nevertheless, theaffected shoots or canes may not be killed, and the disease mayreappear upon such affected plants the following year from thegrowth of the mycelium into young shoots. In the end, practicallyall affected plants are killed, and their vitality is from the outsetso diminished that productiveness is Fig. 208. Blackberry Rust, C^oma StageTo the left, normal shoots ; to the right, diseased The fungus. The mycelium of this fungus has been carefullystudied in the growing canes. It is intercellular, and grows rap-idly in the direction of formative tissues, or where new cells arebeing produced, extending but slightly into tissues or organs whichhave matured. The mycelium is richly provided with tip of the haustorium enlarges as a knob-like organ, and thisis commonly more or less in contact with the cell nucleus. Themycelium in the root penetrates the parenchymatic cortical cells, PR()T()11\SI I )I( JMYCETES 429 and in the regions where the hyphae are abundant the amount ofstarch is distinctly less than in those not pervaded by the the stem, according to Clinton, the mycelium is found espe-cially in the pith, in a more or less zonal area situated near thefibrovascular system. The young mycelium is more readily seenon account of the gre
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