Diseases of flowers and other Diseases of flowers and other ornamentals diseasesofflower118smit Year: 1940 24 California Agricultural Extension Service [Cir. 118 on the dead plant parts are found roundish or irregular, solid, seedlike or tuberlike bodies, the sclerotia of the fungus. In cottony rot, caused by Sclerotinia sclerotiorum (see 'Cottony Mold,' p. 78), these are black in color may be or V2 incn in length; in crown rot, caused by Sclerothtm delphinii, they are smaller, round, and of a chocolate-brown color; and in southern root rot, caused by 8. Bolfsii they are of about the size,
Diseases of flowers and other Diseases of flowers and other ornamentals diseasesofflower118smit Year: 1940 24 California Agricultural Extension Service [Cir. 118 on the dead plant parts are found roundish or irregular, solid, seedlike or tuberlike bodies, the sclerotia of the fungus. In cottony rot, caused by Sclerotinia sclerotiorum (see 'Cottony Mold,' p. 78), these are black in color may be or V2 incn in length; in crown rot, caused by Sclerothtm delphinii, they are smaller, round, and of a chocolate-brown color; and in southern root rot, caused by 8. Bolfsii they are of about the size, shape, Fig. 7.—Black spot of delphinium. and color of mustard seed (fig. 11, p. 36). These bodies perpetuate the fungus in the soil. Many other plants are attacked by fungi of these types. If plants become affected, there is no control except to destroy affected plants and dig out the roots; let the soil dry out and do not immediately replant with any kind of plants. Mosaic.—Delphiniums are affected by several mosaic or virus dis- eases in which the plants are stunted and dwarfed, or show malformed and yellow leaves or mottled foliage and flowers. As soon as any such signs of disease appear, destroy affected plants and do not take sprouts or cuttings from such plants. Powdery Mildew.—The leaves and stems of both perennial delphin- iums and annual larkspur sometimes become covered with white mildew fungus, Erysiphe polygoni. Delphinium plants resistant to mildew may readily be found in seed-
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