Smut of Oats

Ustilago segetum var. hordei, Ustilago avenae

Ustilago segetum var. avenae, Ustilago segetum var. segetum

Names:

Covered Smut of Oats
Loose Smut of Oats.
Smut of Oats cover both Loose and Covered Smut of Oats and is often combined because the two diseases are caused by variants of the same species and they can't be distinguished in the field.

Description:

Dark brown to blackish mass of powdery spores replaces the Oat grain. The spore mass is covered by a thin, white or grey membrane which usually breaks soon after the head emerges releasing spores to infect flowering Oats. By harvest only the bare stem of the Oat head with some husks may remain. Infected plants may be stunted and are often difficult to see by harvest.

Species Affected:

Oats.

Biology:

Infection is favoured by moist conditions during flowering with temperatures from 15-250C.
Early seeding with into warm soils is often associated with outbreaks.

Life Cycle:

Spores released from infected heads are blown to flowering neighbours where they lodge and remain dormant until planting or germinate and grow into the seed coat then remain dormant until planting. After planting the fungus grows within the plant and proceeds to the florets, destroying developing flowers and replacing grain with the spore mass.

Origin and History:

Distribution:

Significance:

Generally occurs at low levels in WA and can be controlled with seed dressings.

Management and Control:

Use seed from uninfected areas.
Treat seed with a fungicide.
Plant resistant varieties. See Disease Susceptibility of Oat Varieties.

Related and Similar Species:

Bunt of Wheat (Ustilago tritici)
Covered Smut of Barley (Ustilago segetum var. hordei)
Loose Smut of Barley (Ustilago tritici)

References:

1293

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.