Stem rust

Puccinia graminis

Brick red spores are formed in elongated pustules that erupt through the surface of host tissues. The pustules mainly form on stems, but can also occur on leaves and leaf sheaths. The pustules are distinguished from those of the leaf rust fungi by their brick red color and conspicuously tattered edges. As the plants mature, the pustules turn dark and shiny as teliospores are formed.