Perovskia atriplicifolia · Perennial
Powdery mildew: Ensure good air circulation by spacing plants well and prune out affected growth in spring.
Root rot: Plant only in sharply draining soil and avoid overwatering to prevent waterlogging.
Honey fungus: Improve drainage and remove infected plants entirely to prevent spread to neighbours.
Verticillium wilt: Remove and destroy infected plants immediately as there is no chemical cure.
Winter wet damage: Avoid mulching heavily around the crown and ensure the site has excellent drainage.