Why Do My Cornflowers Look Unhealthy?

Are the leaves discolored and distorted?

Are the leaves stems and buds distorted?

Are the leaves stippled with yellow, foliage may be webbed?

Do the cornflower stems break off easily?

Are the cornflower seedlings clipped off at the soil line?

Are the seedlings dying?

Do the leaves have water-soaked or white spots on them?

Are the leaves pale on their upper side and are there any dusty blisters on the undersides?

Are the leaves greenish-yellow and the growth rate is poor?

Discolored and distorted leaves are caused by leafhoppers. These small, green or brown insects feed by sucking juices from leaves undersides. Leafhoppers may be the carriers of Aster yellows disease, so it is important to keep them in control. Insecticidal soap helps with severe infestations.

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.

Spider mites are known to cause problems for cornflowers. You can control spider mites by spraying plants thoroughly with water 2-3 times a day for several days. For severe infestations, spray plants with insecticidal soap or pyrethrin.

Stalk borers are long, thin, striped caterpillars that eat their way through stalk centers. Small, round stem holes may betray their presence. Once plants are visibly affected, there is no cure. If borers are a regular problem, spray plants with BTK early in the season as borers enter plants.

If the seedlings of your flowers are cut off at the soil level, most likely cause are cutworms. These caterpillars can be 1-2 inches long, brown, or gray. They feed at night by cutting off young plants and sometimes eating them whole. During the day, they are hidden below the soil surface. Control them by introducing parasitic nematodes to the ground. Using BTK spray on the ground will also control their numbers.

If the seedlings are dying the probable cause is a damping-off disease. Damping-off is caused by various soil fungi. Damaged seedlings can't be healed so, the best course of action is to remove them. To prevent damping-off let the soil surface dry between waterings, thin seedlings to avoid overcrowding and do not add nitrogen fertilizers until plants have developed leaves.

White or water-soaked spots on leaves are caused by fungal infections - Downy mildew or Powdery mildew. To control fungal diseases, thin plants to increase air movement. If the weather is wet spray sulfur in the evening.

Likely cause for these symptoms is a fungal disease - Rust. Provide good air circulation around plants by thining them. Avoid making leaves wet when watering. All infected leaves should be removed. Spray leaves with sulfur early in the season to prevent rust or to treat mild infections.

Greenish yellow leaves followed by a poor growth is caused by Aster yellows disease. This disease is transferred by insects leafhoppers. There is no cure for Aster yellows, so the affected plants should be destroyed. Prevent the disease by controlling leafhoppers. Spray the plants with the insecticidal soap 3 times, once every 3 days.

If plants look too leggy, they are not getting enough sun. Plant on a sunnier site next year.