MSU Extension Integrated Pest Management

Fungal leaf spots

Pathogen

Cladosporium paeoniae.

Hosts

Paeonia.

Symptoms

Initial symptoms typically develop after bloom. Small, reddish, circular spots form on the foliage. Lesions may coalesce, making blotchy patches. The upper surfaces of infected leaves become dark purple; the lower surface is brown. Foliage that is infected before it is fully expanded may become slightly distorted. Infection of stems causes reddish streaks.

Spread

This fungus survives on dead plant debris and in soil. Spores are spread by rain or wind.

Management

Remove and destroy infected plant material. Avoid overhead irrigation or carefully time irrigation to limit the duration of leaf wetness.

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