Lupines, also frequently called lupins, are very attractive, easy to grow flowering plants. They are hardy in USDA zones 4 through 9, will tolerate cool and moist conditions, and produce stunning spikes of flowers in a wide range of colors. The only real drawback is the plant’s relative sensitivity to disease. Keep reading to learn more about what diseases affect lupine plants and what can be done about it.
Troubleshooting Lupine Disease Problems
There are quite a few possible diseases of lupines, some more common than others. Each should be handled accordingly:
Brown spot – Leaves, stems, and seed pods can all develop brown spots and cankers and suffer premature dropping. The disease is spread through spores that live in the soil under plants. After an outbreak of brown spot, don’t plant lupines in the same location again for several years to give the spores time to die out.
Anthracnose – Stems grow twisted and at strange angles, with lesions at the point of twisting. This can sometimes be treated with fungicides. Blue lupines are often the source of anthracnose, so removing and destroying any blue lupines might help.
Cucumber mosaic virus – One of the most wide ranging plant diseases, this is most likely spread by aphids. Affected plants are stunted, pale, and twisted in a downward direction. There is no cure for cucumber mosaic virus, and affected lupine plants need to be destroyed.
Bean yellow mosaic virus – Young plants begin to die and flop over in a recognizable candy cane shape. Leaves lose color and fall off, and the plant eventually dies. In large established plants, mosaic bean disease may only affect certain stems. The disease builds up in clover patches and is transferred to lupines by aphids. Avoid planting clover nearby and deter aphid infestations.
Sclerotinia stem rot – White, cotton-like fungus grows around the stem, and parts of the plant above it wither and die. The fungus lives in the soil and mostly affects plants in wet regions. Don’t plant lupines in the same spot again for several years after this Sclerotinia stem rot occurs.
Oedema – With oedema, watery lesions and blisters appear all over the plant, as the disease causes it to take in more water than it needs. Reduce your watering and increase sun exposure if possible – the problem should clear up.
Powdery mildew – Gray, white, or black powder appears on the leaves of plants having powdery mildew. This is usually a result of too much or improper watering. Remove affected parts of the plant and be sure to water only the base of the plant, keeping the leaves dry.