Plant Disease Management Handbook

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Greenhouse Plants, Ornamental - Impatiens Necrotic Spot

Symptoms Yellow, white, or brown spots are often observed with a brown border. Less frequently seen are mottle or mosaic symptoms. The cultivars Calypso, Summer Madness, and Super Blue Magic are good indicators of both tomato spotted wilt virus and impatiens necrotic spot virus.

Cause Damping-off refers to a disease that develops on the seed, radicle, hypocotyl, epicotyl, or stem of an emerged seedling. Damping-off is caused by the organisms Pythium spp., Rhizoctonia solani, and Fusarium spp. These organisms also can cause stem lesions and root rot of older plants.

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Greenhouse Plants, Ornamental - Gray Mold

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Greenhouse Plants, Ornamental - Black Root Rot

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Vinca spp. (Periwinkle)

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Greenhouse Plants, Ornamental-Pythium Seed Rot, Damping-off, and Root Rot

Cause Golovinomyces cichoracearum (formerly Erysiphe cichoracearum) has been reported in Washington, and Podosphaera fusca (formerly Sphaerotheca macularis) has been reported in Washington and Idaho. The classification in the rest of the world has Podosphaera pericallidis. The fungi are favored by conditions that produce high humidity but dry leaves.

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Greenhouse Plants, Ornamental - Impatiens Necrotic Spot

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Petunia (Petunia spp.) - Damping-off

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Greenhouse Plants, Ornamental - Gray Mold