Leaf spot infection and symptoms in oats

Although a relatively rare disease, management of oat seed sources is important to avoid crop infection. Find out about the seedborne and splash-borne phases and how they contribute to disease spread.

The pathogen that causes leaf spot – Pyrenophora avenae (Drechslera avenae) – is specific to oats.

The primary (seedbourne) phase of the disease starts from infected seed sources.

Infected debris is not thought to be a significant part of the disease cycle.

In severe infections, seedlings die before or soon after they emerge.

On surviving plants, initial symptoms show as short, brown stripes with purple edges on the emerging leaves (especially the first three or four leaves).

The secondary phase of the disease appears as red-brown spots with purple margins on leaves.

The spots contain spores (especially those on the earliest-forming leaf stripes) that splash up the plant.

Eventually, upper leaves develop spotting symptoms and produce spores that splash up onto the ear. When this occurs, grain becomes infected, completing the life cycle.