Mildew on Acanthus

Plants in the Acanthus family are susceptible to mold and mildew development. Planting your Acanthus in well-drained soil helps prevent diseases such as powdery mildew.

Identification

Powdery mildew is caused by fungi that produce a gray or white coating on affected plants. This disease is especially severe in areas where the climate is hot and dry. Acanthus are susceptible to the development of powdery mildew, as are roses, lilacs, turfgrass and vegetables.

Symptoms

Acanthus developing powdery mildew will have a gray or white fungal coating on leaves and stems. Small, black fruiting structures often develop on affected plants as well. Powdery mildew is most noticeable on the upper leaf surfaces and also causes leaf distortion. Acanthus with powdery mildew may experience premature leaf drop and fail to bloom.

Control

Prevention is key to avoiding powdery mildew on Acanthus. Planting disease-resistant plants in soil with adequate drainage prevents powdery mildew. Remove all infected leaves and destroy them to avoid spreading the disease. Chemical controls such as the application of fungicides may help reduce powdery mildew symptoms.

References

• "Fine Gardening": Acanthus mollis (Bear's breeches)
• Lady Bird Johnson Wildflower Center: Lonicera sempervirens L.
• Colorado State University Extension: Powdery Mildews