Lupins (Lupinis) are annual or perennial herbs belonging to the pea family (Fabaceae). Common varieties include the Texas bluebonnet, the Carolina lupin and the wild lupin. Lupin plants are susceptible to a number of plant diseases.
Lupins are susceptible to numerous fungal diseases including root rot (Pythium), downy mildew (Peronospora), powdery mildew (Erysiphe) and rust (Puccinia).
Symptoms of fungal diseases include brownish-black, collapsed roots and rust-coloured spores forming on stems or leaves. Downy mildew appears as grey or white patches on leaves, while powdery mildew causes a coating of white or grey dust to form on leaves.
Lupin plants are vulnerable to the mosaic and ringspot virus. Symptoms include mottled or yellowed leaves, stunted growth and deformed flowers and buds.
Leaf spots commonly appear on lupin plants. These spots are caused by various pathogens and are more prevalent during wet conditions.
Nematodes, aphids (Macrosiphum albifrons) and garden millipedes (Macrosiphum albifrons) most commonly attack lupins. Nematodes are the most serious, attacking and feeding on the plant's root system and causing the foliage to wilt and lose colour.
Infected lupins should be removed and destroyed immediately so they don't spread diseases to other plants. Reducing leaf wetness and humidity levels can prevent most lupin diseases.