Leaf Spot


Pyrenophora avenae (Drechslera avenae)


The disease is specific to oats.


The primary phase of the disease (from seed-borne infection) appears as short brown stripes with purple edges on the emerging leaves. These stripes appear on the first three or four leaves of emerging seedlings. The secondary phase of the disease (splash-borne spores) appears as red-brown spots with purple margins on leaves.

Life Cycle


The primary phase of the disease arises from seed-borne infection. Spores from the early leaf stripes then splash up the plant, producing the secondary leaf spot phase of the disease. Eventually spores splash up onto the ear where the grain becomes infected. Infected grain can cause seedling death during or soon after emergence. Surviving seedlings give rise to the primary phase of the disease. Infected debris is not thought to be a significant part of the disease cycle.


The disease is no longer a serious pathogen of oats. Although it is not uncommon, severe outbreaks are very rare and probably associated with repeated home-saving of untreated seed.

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