Heuchera Rust
Thursday, 12 April 2007 09:37
Rust on Heuchera
Rust fungi are obligate parasites that need to grow and develop on living plants. Fortunately, they don't readily kill infected plants, but their damage can be unsightly. Rust fungi tend to be host specific, affecting closely related plants. They often have complex life cycles. Some types of rust need two different hosts to complete their life cycle, such as Fushsia rust. Other types of rust only need one host to complete their life cycle, such as geranium rust or rust on hollyhock.
Rust on heuchera is caused by the fungus Puccinia heucherae. This fungus is only reported on Heuchera and Saxifraga. It will not spread to other types of perennials susceptible to rusts such as daylilies, hollyhock, campanula or ornamental grasses.
Look for spots on the upper surface of the leaves. Raised eruptions develop on the lower surface. (See photos). If you tap the foliage over a sheet of white paper, you may see an orange, rust-colored smudge. These small, rust spores are spread from plant to plant by air movement.
Apply appropriate fungicides as needed. A listing of fungicides labeled for rust diseases is listed in the New England Recommendation Guide. To prevent the development of resistance, alternate applications between different site-specific chemical groups with different numbers. Growers can also cut back infected plants to remove diseased foliage. However, apply fungicides before cutting back foliage (to reduce the spread of the rust spores) and then reapply fungicides to protect developing new growth from infection.
Photos: Heuchera Rust
Leanne Pundt
Fact Sheet: Rust Diseases of Ornamental Crops
