- Ustilago nuda in barley
- Ustilago tritici in wheat
Why Does it Matter?
- TLS is an internal smut, meaning the fungus grows within the plant rather than on the surface. Diseased plants look normal until heading, which is when the disease manifests itself visually.
- Yield loss. Smutted grain is empty grain. Losses can range from 1% to 40% and are in direct proportion to the percentage of infected heads.
- Grade loss. The tolerance levels for smut are very low and are as follows:
| Seed Grade | Maximum % TLS in Barley |
| Canada Foundation No. 1 | 2% |
| Canada Foundation No. 2 | 4% |
| Canada Registered No. 1 | 2% |
| Canada Registered No. 2 | 4% |
| Canada Certified No. 1 | 2% |
| Canada Certified No. 2 | 4% |
| Common No. 1 | 4% |
| Common No. 2 | 6% |
What are the Symptoms?
- Infected heads are black and filled with dusty spores.
- Symptoms are apparent from heading to maturity and on tillers that may be stunted.
- Florets in infected heads are destroyed and transformed into a dark spore mass covered with a delicate membrane.
- Blackened heads generally emerge shortly before the healthy green ones.
- After spores are released only the bare spike remains.
What is the Disease Cycle?
- The fungus overwinters in the seed’s embryo.
- When the seed germinates, the fungus is activated and colonizes the growing point of the plant.
- As the head develops, all the tissue except the central spike is invaded and converted to spores that are covered by a delicate, easily ruptured membrane.
- The spores mature by the time healthy tillers are heading out and are dispersed by wind and rain.
- Infection occurs when spores land on open wheat or barley flowers, and the fungus is established in the embryo, even though the seed appears healthy.
How is it Controlled?
- Use only clean, tested, disease-free seed.
- Use seed treatments with systemic properties.
How Does 20/20 Seed Labs Inc. Test for TLS in Wheat and Barley?
- 1,000+ embryos are extracted.
- Acid and stain are added to clear the embryos and stain the fungus, if it is present.
- 400 embryos are examined by a qualified technician for the presence of Ustilago nuda mycelium, or Ustilago tritici.
- This test gives the percentage of infected embryos to 0.25%.
- The test takes 3 days to complete.
Please contact us for more information.
