Crown or Leaf Rust (fungus - Puccinia coronata f. sp. avenae): This fungus overwinters on volunteer and wild oats. Alternate hosts of this rust are species of Rhamnus.The disease appears as tiny, round, yellowish-red pustules on either surface of the leaf blade. These pustules produce tiny yellow-red spores that are spread to other plants by wind currents and germinate in free moisture from dews and rains. Crown rust, like other rusts, is caused by a fungus that attacks the leaves and leaf sheath of oats and related grasses. Grazing the infected crop is a suitable means of salvaging value from the crop when damage is heavy. Some varieties have resistance.
