Alstroemeria Disease

The alstroemeria is commonly known as the Peruvian lily or Inca lily. It is native to South America. The alstroemeria was introduced to Europe during the 18th century. The flowers grow well in warm climates, but can be grown in cooler climates (USDA hardiness zone 6 or less in the United States) in pots as a houseplant or in greenhouses.

Growing Conditions

The Alstroemeria grows to an average of 28 inches, but is known to grow as tall as 40 inches. The alstroemeria prefers heat and well-drained, moist, slightly acidic soil. While the alstroemeria will grow in mostly sun, it prefers full sun (more than six hours of continuous sunlight per day). If the alstroemeria is grown in cooler areas, full sun is a requirement.

Mosaic Virus

The mosaic virus affects the foliage of the alstroemeria through chlorosis. No cure exists for this virus, and infected plants should be discarded immediately, as the mosaic virus will spread from plant to plant. The symptom of mosaic virus is mottling of the leaves.

Mosaic Virus Management

Choose alstroemeria varieties that are resistant to mosaic virus. Control weeds around the plant. The weeds could be infected with the virus, which in turn, affects the alstroemeria. Mosaic virus is also spread by insects. If you notice insects around your alstroemeria, treat with the proper insecticide. Contact your local nursery for the insecticide used for the type of insect on the alstroemeria (i.e. aphids).

Impatiens Necrotic Spot Virus

The Impatiens necrotic spot virus (INSV) affects the alstroemeria, producing several symptoms. Symptoms include stem cankering, yellow or brown spots, ringspots, chlorotic mottle and stunted growth. Impatiens necrotic spot virus can be contained by removing western flower thrips (they will carry the disease from one plant to another) and by keeping the greenhouse or plant area free from weeds. Contact your local nursery for the proper fungicide to treat plants affected with INSV.

Basal Rot

Basal rot of the alstroemeria is caused by fusarium oxysporum. The symptoms of basal rot are hollow stems that become constricted at the base; yellowing of the leaves that progresses from the lower leaves to the upper leaves; and roots and rhizomes with brown rot. Stunted growth of some of the stems might also be noticed. Discard infected plants.

Leaf Spot

Leaf spot is caused by several things, but the majority are caused by fungal pathogens. Some are caused by bacteria. The most common leaf spot cause is anthracnose-a group of related fungal diseases. Anthracnose causes blotches on the leaves. The spots might vary in color and size, depending on what caused the leaf spot, but are generally black or tan in color. Some leaf spots have concentric rings around them.

Remove leaves affected with leaf spot. Be sure to keep weeds and plant debris from fallen and pruned plant matter away from the plants. Water the alstroemeria from below if you notice leaf spots. Keeping the leaves dry help to prevent the spread of leaf spot.