Why Do My Ornamental Alliums Look Sickly?

Are there no flowers, and the growth is stunted?

Are there any water-soaked, brown lesions on the bulbs?

Are the leaves streaked with gray or brown?

Do the leaves have pale areas on upper surfaces and "downy" patches underneath?

Do the leaves have large, ragged holes in them?

Do the leaves have white or translucent tunnels in them?

Are the seedlings stunted or wilting, the plant will commonly break at soil line if an attempt is made to pull it up?

Bulb rot is a fungal disease that causes the bulbs to become mushy or dried out. The foliage becomes yellow and stunted, and the Alliums may not flower. Dig up and discard infected bulbs. Bulbs purchased from a reputable dealer rarely develop bulb rot.

Bacterial soft rot is caused by a bacterium that is common in most soils, particularly if the area is frequently planted with susceptible crops. Remove and destroy infected plants. Avoid planting in poorly draining soil. Control insect pests such as onion maggot, that can spread it. Plant varieties that are resistant to the disease.

Onion thrips cause gray or brown blotches on allium leaves, tips may be distorted or brown. Adults are tiny, slender, yellow to brown, rapidly moving, winged insects. The larvae can barely be seen with the naked eye. Treat plants with insecticidal soap or a commercial pyrethrin spray or dust to control thrip infestations.

Pale areas on upper surfaces of the leaves and "downy" patches underneath are caused by Downy mildew. This fungus spreads quickly during cool, wet nights and warm, humid days. Leaves will wilt and die. Remove and destroy all affected plant parts and encourage good air circulation around plants by thining them. Water plants early in the morning to make sure they dry before nightfall.

Large, ragged holes in the leaves are caused by slugs and snails. Slugs and snails feed on the plant leaves usually at night. To control slugs and snails use diatomaceous earth around your plants. You can also handpick them during the night or use shallow dishes filled with beer as a trap.

If the leaves have white or translucent tunnels in them the culprits are leafminers. These tiny white, maggotlike larvae feed inside leaves. Prune off and destroy all infested leaves. Cover plants with row cover until flowers open to prevent adults from laying eggs on plants. Certain nematodes can attack leafminer larvae inside leaf tunnels.

Onion maggots feed on roots, killing seedlings and older plants. Onion maggots are white and taper to a point at the head. Destroy infested plants. Do not compost them. Apply parasitic nematodes to the soil before planting and cover plants with row cover.

Dog urine may discolor and kill ornamental onion foliage. Spraying foliage with an anti-transpirant gives some protection. Screen the Alliums or spray them with an aerosol pet repellent.