What Is Attacking My Calendula?

Are the leaves stems and buds distorted?

Are the leaves yellow and the plant looks weakened?

Are the leaves discolored and distorted?

Do the leaves have large ragged holes in them?

Are there any slimy trails of mucus on the plant?

Do the flower buds fail to open?

Do the leaves have a powdery white coating on them?

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

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.

Yellow leaves and stunted look are caused by whiteflies. These tiny, mothlike flies and their larvae feed by sucking plant juices. Whiteflies secrete honeydew, a sugary substance that makes leaves sticky to the touch. Control whiteflies by eliminating garden weeds and by introducing green lacewings in the garden. Spray infested plants with insecticidal soap every 3 days for 2 weeks.

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.

Slimy trails and the holes in the leaves are left 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.

Cabbageworms are green caterpillars with a yellow back stripe and yellow side spots. They are known to feed on calendula leaves and leave large holes in them. Handpick cabbageworms or spray leaves with BTK when pests first appear.

Thrips are known to cause problems to calendulas, although they tend to be a minor threat. In severe cases, infested plant parts should be pruned off and destroyed. Control thrips by introducing lady beetles or lacewings. Insecticidal soap helps in severe infestations.

White, powdery coating on the leaves is caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining any surrounding plants. Water plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. Any commercial fungicidal spray will protect your plant from further 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 the leaves have dark, concentrically ringed spots on them, the cause might be fungal disease - Alternaria blight. The disease occurs during humid, warm (75°-85°F) weather. Spray infected plants with copper and/or sulfur to prevent further disease development.