Rust

A term used to describe a range of fungal organisms which cause this disease, although it should not be cause for major concern in the UK as good turfcultural practices should be adequate to prevent or at least limit any damage from rusts. Puccinia species are the main cause of a yellowing of a leaf along with a subsequent orange-brown rusty colour on the leaf, with an irregular arrangement of small bumps (pustules) on the leaf consisting of dusty-powdery spores.