Why Does My Phlox Looks Unhealthy?

Are the leaves covered with white powdery patches?

Are the leaves discolored, fine webbing may be present?

Are the leaves curled and distorted?

Are the leaves stippled and distorted?

Are the flowers discolored and deformed?

Are the flowers deformed?

Are the leaves spotted or blotched?

Do the crowns and roots rot, an unpleasant odor may be present?

Do the plants look spindly or leggy?

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.

Spider mites often cause problems for phlox plants. 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 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.

Aster leafhoppers are greenish-yellow, tiny insects that feed on leaf undersides, giving the foliage a finely mottled look. Leaves yellow, shrivel and drop. Besides injury from feeding, leafhoppers transmit the disease aster yellows. Use water or insecticidal soap sprays to dislodge nymphs. Encourage enemies such as big-eyed bugs and parasitic wasps. For control of severe infestations, spray plants with neem or pyrethrin.

Discolored and deformed flowers are caused by Aster yellows disease. This disease is transferred by 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.

Deformed flowers in phlox are most likely caused by Phlox Plant Bugs. Adult phlox plant bugs are reddish-orange, with a black stripe running down their back. Adults and nymphs sting flower buds, causing them to be deformed. Spray the pests with a pyrethrin insecticide, taking care to follow label directions. Cut and discard dead growth and debris after the first frost to eliminate overwintering eggs.

Your plants might be suffering from fungal leaf spots. 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. Prevent problems by thinning plants to provide good air circulation.

Phlox can occasionally be infected by fungal and bacterial Crown or Root rot diseases. Crown injury and excess moisture during dormancy also increase the chances of infection. Choose well-drained sites. Add organic matter to improve soil drainage. Keep winter mulch away from crowns. Remove and discard infected plants and the surrounding soil.

Lack of sunlight will cause phlox to grow spindly or leggy. Phlox need lots of direct, bright sun to flourish. If they are shaded, they are forced to stretch to reach the light, causing them to develop thin stems. Trim away nearby overgrowth that may be blocking their access to light. Transplant them to a sunnier spot in the fall.

If the blooming had stopped, the plant might have set seeds. Snip off the faded flower heads from phlox stems. If the flowers begin to develop into seeds, the plant will no longer produce flowers, since its life cycle has been completed.