What is wrong with my Jostaberry plant?

Are there any white mildew growth (turning brown with age) on young shoots and fruits?

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

Are the leaves discolored, fine webbing may be present?

Are the leaves, stems, and buds distorted and sticky?

Is the foliage covered with small bumps, cottony masses may be present?

Do the leaves have spots or blotches?

American gooseberry mildew is a fungal disease that attacks jostaberries. The fungal growth on the berries can be rubbed off, so there is no need to waste the crop if many of the fruits are affected. Encourage good air circulation around the affected 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.

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.

Spider mites are known to cause problems for jostaberries. Hose off plants when symptoms first appear. A strong stream knocks mites off plants and may give control. Introduce predatory mites. For severe infestations, spray plants with insecticidal soap or pyrethrin.

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.

White, cottony masses, or brownish bumps on foliage and stems 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.

Your plants are suffering from fungal leaf spots. These can come from several fungi. Spots may enlarge rapidly, especially in wet weather. Destroy infected leaves or plants. Spray plants with sulfur to prevent the disease from spreading, especially if the weather is wet. Spray between rains. Prevent problems by thinning plants to provide good air circulation. Fallen leaves and debris should be removed promptly to avoid spreading the disease.

If the foliage gets rapidly devoured by caterpillar-like larvae that are green with black dots the culprits are gooseberry sawflies. Check plants regularly from April for the presence of larvae and remove them by hand where practical. If the larvae are too numerous for hand picking, control may be achieved by spraying with pesticides. Several applications of organic contact insecticides containing natural pyrethrins may be necessary to give good control.