Description:Dark brown to purple spots develop into tan to dark brown oval or irregularly shaped blotches, to 2 cm round, with yellow rims on leaves in late winter to spring and cover and kill the entire leaf. It may spread to leaf sheath then stems forming grey brown or shiny black blotches. Dark brown blotches may appear on the head and grain. Lodging may occur in severe attacks. Tiny black fruiting bodies may be seen in the centres of older blotches.
Species Affected:Oats, Wild Oats.
Biology:More common in warm, moist conditions.
Life Cycle:Fruiting bodies in residues release spores in autumn and are spread by raindrop splash or wind to infect young Oat plants. In very susceptible varieties the initial infection may come from seed.
Origin and History:Distribution:
Significance:Most damaging in early sown and short-straw crops.
Management and Control:Sow resistant varieties. See Disease Susceptibility of Oat Varieties.
Related and Similar Species:Septoria Nodorum Blotch of Wheat (Phaeosphaeria nodorum)