Detailed profiles of common plant diseases, pests, nutrient deficiencies and environmental problems.
Cucurbit downy mildew is a rapidly developing foliar disease caused by the oomycete Pseudoperonospora cubensis. It produces pale yellow to brown, angular leaf spots…
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Pseudomonas viridiflava is a bacterial plant pathogen with a broad and variable host range. Depending on the crop and strain, it may cause water-soaked…
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Bacterial speck is a bacterial disease of tomato caused by Pseudomonas syringae pv. tomato. It produces tiny black leaf and fruit lesions, often with…
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Pseudomonas syringae pv. syringae is a bacterial pathogen with a broad and variable host range. In the United States it can cause leaf spots,…
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Pseudomonas syringae pv. morsprunorum is a bacterial pathogen associated mainly with bacterial canker, blossom blast, bud death and shoot dieback in cherry and other…
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Olive knot is a chronic bacterial disease of olive trees caused by Pseudomonas savastanoi pv. savastanoi. It produces rough, tumor-like galls on twigs, branches,…
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Tomato pith necrosis is a bacterial disease most strongly associated with Pseudomonas corrugata, although similar symptoms can be caused by several other soilborne bacteria.…
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Obscure mealybug (Pseudococcus viburni) is a sap-feeding insect pest of grapevines, fruit trees, greenhouse crops and ornamentals. Colonies hide in leaf axils, beneath bark,…
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The long-tailed mealybug, Pseudococcus longispinus, is a sap-feeding insect pest of greenhouse, houseplant, nursery, orchard and warm-climate landscape plants. Colonies hide in leaf axils,…
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Prunus necrotic ringspot virus is a systemic viral disease of stone fruits and some ornamental hosts, including roses. Symptoms vary widely by virus strain,…
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The root-lesion nematode, Pratylenchus penetrans, is a microscopic soil pest that penetrates living roots and migrates through the cortex, producing reddish-brown lesions and a…
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Potato virus Y (PVY) is a virus disease affecting potatoes and other members of the nightshade family. Symptoms range from mild leaf mosaic and…
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