What Is Wrong With My Black Chokeberry?

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

Are the leaves covered with white powder?

Are there any oozing cankers on the branches and buds?

Are there any silky caterpillar tents in the branches in late summer?

Are the fruits dimpled with brown tunnels in the flesh?

Are the leaves curled and distorted?

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.

White, powdery patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from below to keep foliage dry. Any affected leaves should be cut off and removed. The appropriate fungicidal spray will protect your plant from further infections.

Oozing cankers on the branches and buds are caused by bacterial blight. The spread of the disease is greatest during humid, wet weather conditions. Practice good garden hygiene at the end of the season and discard, do not compost, possibly diseased plants and plant parts. Space plants to allow for adequate air circulation. Prune all infected branches below cankers.

Fall webworm is a caterpillar that makes silky tents during Fall. Fall webworms are usually held in check by songbirds, yellow jackets, wasps, and rodents. You can easily remove the webs when they occur in trees. Insecticides are seldom necessary for fall webworm, especially in trees, and should be considered only if the infestation is heavy. Bacillus thuriengensis (BT) can be used when the caterpillars are small, but it will not provide satisfactory control once the webs are large.

Apple maggots are 1/4 of an inch small maggots that feed by tunneling through fruits of apples and other fruits like black chokeberries. In late June they morph into adult flies. Since they are attracted to the fruit by sight, you can trap them by hanging red balls with a sticky coating on the trees. 4-8 traps by a tree will be enough to control their numbers. You should clean traps every few days and reapply the sticky coating.

Distorted and curled leaves are caused by aphids. These tiny insects 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 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.