Downy mildew, caused by Plasmopara pygmaea, forms a fine white mildew on the lower leaf surface. The plants are discolored and distorted and the stems aborted. Destroy badly infected plants. No chemical control is listed. Rust causes thickening and paling of the leaves and crown.
Brown pustules form on the undersides of leaves.
Badly infected plants are destroyed. Sprays of sulfur control the disease. Smut symptoms are dark brown powdery pustules on swollen regions of the leaf stalks and blades. Destroy diseased leaves. The causal fungus is Urocystus anemones.