If you think rust only happens to metal, think again. These are rusts – actually fungi – that cause diseases in plants; anything from trees and shrubs in the local park to the fruit and vegetables you lovingly tend in your home garden can be affected by rusts, sometimes fatally. There are around 7000 species of rust but they are more readily identifiable than you might think as many are specific to particular plants – often it’s a case of name the plant, name the rust.
Rusts are most visible when they form disfiguring spots on the upper surfaces of leaves, and pustules on their undersides, as well as on the stalks and sometimes the flowers and fruit of plants. Just like most other fungi, rusts produce spores, in this case in their millions from within the pustules. Though they are the bane of most gardeners, rusts can be interesting and attractive fungi to examine and study. The photos shown here are: Puccinia acetosae on Dock (Rumex sp.) (above), Puccinia circaeae on Enchanter’s-nightshade (Circaea lutetiana), Puccinia coronata on Creeping soft-grass (Holcus mollis), Puccinia magnusiana on Buttercup (Ranunculus sp.), Puccinia phragmitis on Dock (Rumex sp.), Puccinia poarum on Coltsfoot (Tussilago farfara), and Puccinia sessilis on Lords-and-Ladies (Arum maculatum).