Detailed profiles of common plant diseases, pests, nutrient deficiencies and environmental problems.
The strawberry foliar nematode, Aphelenchoides fragariae, is a microscopic pest of strawberry foliage and crowns that also affects many ferns, herbaceous perennials and vegetatively…
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Aphanomyces root rot is a persistent, soilborne disease of peas, alfalfa and several other legumes caused by the water mold Aphanomyces euteiches. It is…
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California red scale, Aonidiella aurantii, is a sap-feeding armored scale insect that most seriously affects citrus in warm regions of the United States. Immobile…
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The strawberry blossom weevil (Anthonomus rubi) is a small Eurasian weevil that attacks berry crops by feeding on young foliage and unopened flower buds.…
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The apple blossom weevil, Anthonomus pomorum, is a flower-bud-feeding weevil primarily associated with apple trees. Adults emerge from overwintering sites in early spring, feed…
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Early blight is a widespread fungal disease of tomato, potato and other nightshades caused by Alternaria solani. It usually begins on older, lower leaves…
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Purple blotch is a fungal leaf disease of onions and related Allium crops caused by Alternaria porri. It begins as small, water-soaked or whitish…
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Alternaria dauci causes carrot Alternaria leaf blight, a fungal disease that usually begins as small brown to black spots with yellow margins on older…
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Alternaria brassicae is a fungal pathogen associated with Alternaria leaf spot, also called black spot or gray leaf spot, on brassica crops. It produces…
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Alternaria alternata is a widespread, opportunistic fungal pathogen that causes leaf spots, blights, stem lesions and fruit rots on numerous crops and ornamentals. Symptoms…
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Woolly whitefly, Aleurothrixus floccosus, is a sap-feeding insect that primarily attacks citrus and may also occur on Eugenia. Immature stages live on leaf undersides…
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White rust, also called white blister rust, is an oomycete disease of cruciferous plants caused by Albugo candida. It produces raised, chalky-white pustules—usually on…
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