Omphalina patch disease in wheat and barley

Although not considered a serious disease in UK cereal crops, omphalina patch is associated with some unusual symptoms. Learn about the pathogen’s life cycle and how to spot signs of its presence in fields.

The pathogen that causes omphalina patch (Omphalina pyxidata) affects wheat, barley and grasses.

It is believed to be sporadic in nature and only affects a small number of crops each year – mainly winter barley and crops on light land.

Limited trials on winter barley suggest infection can reduce fertile tiller numbers by 40% and yields by 25–50%.

It is a soilborne fungus that survives between susceptible hosts as sclerotia or as mycelium on root debris.

It infects crops soon after emergence.

Roots and the soil adjacent to affected plants show characteristic white hyphal masses (like small pieces of cotton wool about 1 mm across).

As early as December, affected patches can be visible as sharply delineated but irregular areas of stunted growth.

Foliage colour is not normally affected.

Affected crops may develop white-heads.

Fruiting bodies (basidiocarps), like tiny mushrooms (about 2 cm high with a 1 cm diameter convex cap), sometimes appear within affected patches between January and March.

The basidiocarps release airborne basidiospores.