. ¥ Fig. 33.—Spotted wilt of sweet pea causing so-called streak disease. The disease, caused by a virus, is spread by the pea aphid, Illinoia pisi. The spread of mosaic may be delayed by dusting with nicotine to keep down the aphids. Powdery Mildew.—The leaves and buds become covered with a white, powdery fungus, Erysiphe polygoni, which causes stunting of the growth and worthless flowers. To control, dust frequently with dry, powdered sulfur, beginning before mildew develops. This may be combined with nicotine dust for aphids.

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Keywords: ., bo, bookcentury1900, booksubjectflowers, booksubjectplantdiseases