What Is Wrong With My Buddleja?

Do the leaves have pale areas on upper surfaces and "downy" patches underneath?

Does your plant shows symptoms like pale or reddish leaves, small leaves, defoliation, branch dieback, stunting, and death?

Do the plants have wilted leaves and dried stems that don’t respond to watering?

Are the leaves discolored, fine webbing may be present?

Are the leaves curled and distorted?

Are there any irregular serpentine tunnels in the leaves?

Pale areas on upper surfaces of the leaves and "downy" patches underneath are caused by Downy mildew. This fungus spreads quickly during cool, wet nights and warm, humid days. Leaves will wilt and die. Remove and destroy all affected plant parts and encourage good air circulation around plants by thining them. Water plants early in the morning to make sure they dry before nightfall.

Phytophthora root rot is a soilborne disease promoted by wet soil conditions. Once the disease has been introduced to a field then there is no method of treatment. Remove infected plants. Do not plant related plants in the same area.

These symptoms could indicate a fungal disease - Rhizoctonia Root Rot. Improve soil drainage by working some compost into the top ten inches. Discard all infected plants. Do not overwater plants. Pot in the pasteurized soil mix. Apply a copper-based fungicide to protect plants.

Spider mites often cause problems for buddlejas. 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 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.

Tunnels in leaves are caused by leafminers. These tiny fly larvae feed within the leaves in meandering mines that become wider as the larvae grow. Prune off and destroy all infested leaves. Remove debris in fall because it might contain overwintering leafminers. Introducing parasitic wasps is a very effective method of controlling leafminers.

If the foliage has turned yellow in patches between the leaf veins, and then turned brownish-black without the formation of spores the culprits are foliar nematodes. These microscopic worm-like creatures feed on the leaves of some plants. Symptoms usually appear on lower leaves first, and then spread to upper leaves. Remove and destroy infested leaves, and the next two leaves directly above them. Make sure to water plants from below. Do not replant buddlejas in the same soil if the infestation was severe.