See:
Fungicide Effectiveness as Seed Treatments for Cereal Diseases
Cause The fungus Ustilago tritici (= U. nuda). It survives a long time in barley seed. Infected seed is fully viable and not visibly different from uninfected seed. Infection is only during flowering. The disease is favored by moderate temperatures (61°F to 72°F) and wet, cloudy weather, thus is less common in arid regions.
Symptoms Smutted heads emerge from the boot earlier than healthy heads. The paper-like membrane that first encloses the dark brown spore mass soon ruptures, and wind blows spores to healthy heads. Under some conditions, smut may be visible on flag leaves, sheaths, or culms.
Cultural control
- Use pathogen-free seed.
- Plant resistant varieties, such as 'AC Metcalfe' or 'Morex'.
Chemical control The disease is not controlled by surface-active protectant fungicides as seed treatments.
- Charter (Group 3) at 3.1 fl oz/100 lb seed plus a dye. See label for rotation and reentry restrictions.
- Raxil MD (Group 3 + 4) at 5 to 6.5 fl oz/100 lb seed plus a dye. See label for reentry restrictions.
- Vibrance (Group 7) at 0.08 to 0.16 fl oz/100 lb seed plus a dye. See label for reentry restrictions.
Note: Apron, Captan, or Thiram alone are ineffective.
Reference Mathre, D.E. 1997. Compendium of Barley Diseases. St. Paul, MN: APS Press.