Detailed profiles of common plant diseases, pests, nutrient deficiencies and environmental problems.
Leveillula taurica causes an unusual powdery mildew of peppers, tomatoes and other warm-season crops. Unlike many powdery mildews, the fungus grows mainly inside the…
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Lettuce mosaic is a viral disease caused by Lettuce mosaic virus. It is especially important because the virus may arrive in contaminated seed and…
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Blackleg, also called Phoma stem canker, is a serious fungal disease of canola, rapeseed and other susceptible Brassica crops. Early infections produce gray-green leaf…
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Brown spot needle blight is a fungal disease of pine needles caused by Lecanosticta acicola, formerly known under names including Mycosphaerella dearnessii and Scirrhia…
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Corn eyespot is a residue-borne fungal leaf disease caused by Kabatiella zeae, also known by its current name Aureobasidium zeae. It produces small, translucent…
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Impatiens necrotic spot virus (INSV) is a serious, thrips-transmitted disease of greenhouse and garden ornamentals in the United States. Symptoms vary widely by host…
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Ash dieback is a destructive fungal disease of ash caused by Hymenoscyphus fraxineus, formerly associated with the names Chalara fraxinea and Hymenoscyphus pseudoalbidus. Typical…
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Hyaloperonospora parasitica is an oomycete associated with downy mildew on selected plants in the mustard family, including shepherd’s purse and some ornamental brassicas. Identification…
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Heterobasidion root disease—historically called annosus root rot or annosus root and butt rot—is a destructive fungal disease of conifers. It often remains hidden until…
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Pear trellis rust is a fungal disease caused by Gymnosporangium sabinae. It produces yellow-to-orange leaf spots, swollen or distorted young fruit, and conspicuous tube-like…
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Cedar-apple rust is a two-host fungal disease caused by Gymnosporangium juniperi-virginianae. It alternates between eastern red cedar or susceptible junipers and apple or crabapple.…
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Black rot of grape, associated with the fungus currently known as Phyllosticta ampelicida and formerly Guignardia bidwellii, is a destructive disease of grapevines in…
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