Why Does My Canna Lily Look Unhealthy?

Are the leaves rolled?

Do the leaves and/or flowers have holes in them?

Are the holes large and ragged, and occurring only in leaves?

Are the leaves stems and buds distorted?

Are the leaves covered with small bumps?

Are the leaves tied together and discolored?

Are the flowers covered with gray mold?

Are the buds and flower stalks rotted?

Rolled leaves are caused by canna leafrollers caterpillars. These green caterpillars with brown heads feed on the enclosed leaves and buds. If the infestation isn't severe, handpick the rolled leaves with caterpillars. For severe infestations, use of insecticides is the only way of controlling.

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.

Holes in leaves and flowers in cannas are caused by Japanese beetles. Adults of these insects devour leaves, stalks, and flowers of nearly 300 plant species. Their larvae feed on the roots of the plants. Handpick adult beetles into a can of soapy water but make sure to wear gloves as Japanese beetles are blister beetles. Apply parasitic nematodes to the soil to limit beetle grub populations. Use pyrethrin powder or neem oil as a last resort.

Distorted stems, buds, and leaves are caused by aphids. These tiny insects can vary in color, green, pink, black, gray to completely white. They cluster under leaves and on growing tips where they feed on plant sap. Leaves, stems, and buds get distorted and later leaves and flowers drop from the plant. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

Leaves covered by small bumps are caused by scales. These tiny, shelled insects often feed on the undersides of the leaves, causing an unhealthy appearance with yellowish blotches on the upper leaf surfaces. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season.

Leaftier is a caterpillar that causes the foliage to become ragged, turn brown, and die. If the infestation is light, break open the “envelopes" and pick off the caterpillars. For heavier infestations, spray plants with BTK.

Gray mold on canna flowers is probably caused by fungal disease - Botrytis blight. Other symptoms include brown to black spots that may appear on leaves and petals. You can only prevent Botrytis blight disease by planting canna lilies in areas with good air circulation. Water plants sparsely. Infected plants should be removed. Spray weekly with a copper fungicide until the disease is under control.

Canna bud rot is a bacterial disease that produces watersoaked streaks and spots on new, unfolding canna leaves as well as older leaves. It then spreads to the flowers. A gummy sap may bleed from diseased areas on stalks. The condition is aggravated by overwatering, overcrowding, and poor aeration. Destroy diseased plants.

Some environmental issues may have caused an unhealthy look in your canna lily. Cannas love warm soil, 60°F or warmer. They need a position in full sun and fertile, moist soil. If you live in a zone with harsh winters, dig up canna rhizomes in the fall and replant them again in the spring.