Barley

Covered Smut of Barley

Ustilago segetum var. hordei

Fungus

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In a Nutshell

  • Black kernels.
  • Shrivelled and deformed awns.
  • Stunted plants.

Can also be found in

1 Crops
Barley

Barley

Symptoms

Affected plants usually do not exhibit any symptoms until ear emergence. Infected ears typically emerge at the same time or slightly later than healthy ones. They do often emerge through the sheath below the flag leaf. The most obvious symptom is the discolouration of the kernels, colouring them black. The grains in infected ears are held in place by a tough, greyish-white membrane. Near the harvest, the grains are completely replaced by spores. Awns appear deformed. Barley plants can be stunted in their growth.

Recommendations

Organic Control

Seed treatments with leaf powder of Vitex negundo are effective. Treating your seeds with bio-control agents such as Trichoderma harzianum, T. viride and Pseudomonas fluorescens are less effective in controlling the disease than fungicides.

Chemical Control

Always consider an integrated approach with preventive measures and available biological treatments. Complete disease control was achieved by seed treatment with carbendazim 50 WP (2.5 g), mancozeb 50 WP + carbendazim 50 WP (1 g), carboxin 37.5 WP + thiram 37.5 WP (1.5 g) and tebuconazole 2 DS (1.5 g) per one 1 kg of seeds.

What caused it?

The symptoms are caused by the pathogen Ustilago segetum var. hordei. It is externally seed-borne, meaning diseased plant heads spread the spores to the surface of healthy seeds. When the spore masses are broken open as barley is threshed after harvest, numerous spores are released. Many spores lodge on healthy kernels and remain dormant until the seed is sown. When the barley seed begins to germinate the spores also germinate and infect the seedling. A warm, moist, acidic soil favours seedling infection. The disease favours soil temperatures between 10°C and 21°C during the germination period. Covered smut is sometimes difficult to distinguish from loose smut.

Preventive Measures

  • Use resistant varieties if available.
  • Use disease-free seed materials for planting.
  • Sow your seed in moderately dry soil.
  • Disease incidents can be reduced by sowing seeds 2.5 cm deep.
  • Plant barley in neutral or alkaline soil rather than in acidic soil if possible.
  • Rogue affected plants, uproot and burn them.

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