Plant Disease Management Handbook

Cause Ciborinia camelliae (formerly Sclerotinia camelliae), a fungus that attacks only opened flower parts. Hard brown-to-black fungus bodies (sclerotia) develop in the base of old infected flowers. Sclerotia later produce one or more mushroom-like growths (apothecia), which, in turn, produce spores to cause new petal infections.

Cause Hyaloperonospora camelinae (syn. = Peronospora camelinae, P. parasitica), an oomycete that is favored by cool, wet conditions. In North America, it was first reported in Canada during 1955, where partial host resistance was also identified. This pathogen has been found on camelina grown in western Montana and Nebraska.

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Iris, Rhizomatous (Iris spp.) - Bacterial Soft Rot

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Greenhouse Plants, Ornamental - Gray Mold

Lily (Lilium spp.) - Botrytis Blight (Fire)

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Dieffenbachia - Dasheen Mosaic

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Rhododendron - Phytophthora Blight and Dieback

Cause Fusarium has been reported on California poppy in CA and FL; Verticillium dahliae has been reported in CA. OSU surveys of seed fields over several years in Oregon have detected Fusarium spp. associated with wilting of plants.

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Greenhouse Plants, Ornamental - Gray Mold

Cause Powdery mildew has not been reported formally for the Pacific Northwest, but it is a common garden problem west of the Cascade Range. Golovinomyces cichoracearum (formerly Erysiphe cichoracearum) has been reported from California. This fungus is favored by conditions that produce high humidity but dry leaves. It is a highly specialized pathogen that forms a close association with the host.

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Greenhouse Plants, Ornamental - Impatiens Necrotic Spot

Symptoms The plant's center or only one side may develop a wilt in which leaves turn a greasy gray. Plants eventually collapse without recovering. The disease can be confused with fungal wilt. Symptoms of INSV-infected plants are reportedly similar to symptoms on cinerarias, and plants may be stunted.