Arno Bay Blotch of Barley

Pyrenophora hordei


Small, round to oval, dark brown spots that increase to parallel sided blotches up to 1 cm wide. Larger blotches often have a yellow halo, especially when they are near the tip of the leaf. It produces spores from the blotches and tiny black fruiting bodies that are largely hidden within the plant tissue.

Species Affected:

Barley, Barley Grass.


Survives on Barley residues and probably on Barley Grass residues.

Life Cycle:

Wet conditions in autumn stimulate fruiting bodies within plant residues to release spores that infect young Barley leaves. Lesions develop and wind borne spores are released from the blotches late in the season to infect other plants and distant crops. Tiny, black fruiting bodies are produced in the plant tissue before senescence.

Origin and History:

Discovered in 1990 in South Australia.


South Australia and Western Australia.


Management and Control:

Avoid susceptible varieties. See Disease Susceptibility of Barley Varieties.

Avoid continuous cropping of Barley.

Control Barley Grass in pastures and crops.

Burn, bury or graze Barley residues before planting.

Related and Similar Species:

Boron toxicity looks similar.



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