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Sunflower (Helianthus spp.)-Sunburn Cause Heat or moisture stress can result in a sunburn on the flower heads. Symptoms Brown or blackened areas on the side of the plant continuously exposed to sun. Cultural control Maintain adequate irrigation. ...
Large sunflower leaf
Sunflower (Helianthus spp.)-Verticillium Wilt Cause Verticillium dahliae, a fungus that survives in soil as microsclerotia. Another species V. isaacii has also been isolated from wilted sunflower plants in the Columbia Basin, Washington. Survival structur ...
Sweetpea (Lathyrus odoratus)-Fasciation See: Greenhouse Plants, Ornamental- Shoot Proliferation and Leafy Gall ...
Sweetpea (Lathyrus odoratus)-Mosaic See: Pea (Pisum sativum)- Pea Enation Mosaic ...
Sweetpea (Lathyrus odoratus)-Powdery Mildew Cause Erysiphe pisi var. pisi (formerly Erysiphe polygoni), has been reported from the Pacific Northwest; Erysiphe lathyricola (formerly Microsphaera diffusa) has been reported from Oregon. Erysiphe trifoliorum ...
Sweetpea (Lathyrus odoratus)-Root Rot See: Pea (Pisum sativum)- Root Rots ...
Sweet Woodruff (Galium oderatum)-Powdery Mildew Cause Likely the fungus Neoerysiphe galii since a dense mycelial mat is formed, but 3 different species of Golovinomyces also occur worldwide. Golovinomyces cichoracearum, has been reported for the PNW. Thes ...
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Swiss Chard (Beta vulgaris subsp. cicla)-Damping-off Cause Pythium spp. and Rhizoctonia solani are soil-infesting microbes that can build up rapidly and attack young germinating seedlings when soil is moist. Symptoms Stems are attacked as young plants eme ...
Swiss Chard (Beta vulgaris subsp. cicla)-Downy Mildew Cause The fungus-like microorganism, Peronospora farinosa f. sp. betae, causes disease on beet as well. The microorganism survives in infected crop residues and in wild or volunteer Beta spp. It also c ...
Swiss Chard (Beta vulgaris subsp. cicla)-Leaf Spot Cause A fungus, Cladosporium variable, is believed to be the primary pathogen. This fungus can grow under a wide range of temperatures, but 59°F to 68°F with relative humidity above 80% is most conducive ...