. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. i5o FUNGOUS DISEASES OF PLANTS Symptoms. The effects of the fungus are somewhat various upon the different hosts. Upon the shepherd's purse the stems are enlarged and distorted, while no unusual malformations of floral organs and leaves generally occur. On the radish the floral organs may be strikingly hypertrophied (Fig. 49), ovary sacs greatly enlarged, stamens, petals, and sepals distended and some- times becoming leaf-like. Upon nearly all hosts the porcelaneous. Fig. 50. Conid
. Fungous diseases of plants : with chapters on physiology, culture methods and technique . Fungi in agriculture. i5o FUNGOUS DISEASES OF PLANTS Symptoms. The effects of the fungus are somewhat various upon the different hosts. Upon the shepherd's purse the stems are enlarged and distorted, while no unusual malformations of floral organs and leaves generally occur. On the radish the floral organs may be strikingly hypertrophied (Fig. 49), ovary sacs greatly enlarged, stamens, petals, and sepals distended and some- times becoming leaf-like. Upon nearly all hosts the porcelaneous. Fig. 50. Conidial Stage, Fertilization, and Germinating Oospore of Cystopus. [b and c, after De Bary) conidial cushions, characteristic of the family to'which this species belongs, are prominent. The fungus. The conidial cushions occur upon leaves, stems, and floral parts, or fruits. On the majority of hosts, such as shepherd's purse, horse radish, etc., oospores generally occur only in the stems, yet upon some other hosts, particularly upon certain mustards 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 are produced numerous short, erect, basally branched conidiophores. The latter give rise to simple chains of spores in basipetal suc- cession. These are usually separated one from another by slight. 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 may not perfectly resemble the original Duggar, Benjamin M. (Benjamin Minge), 1872-1956. Boston ; New York : Ginn
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