Common bunt
Ustilago levis
1. Appearance and Symptoms:
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Teliospore Mass: The most characteristic symptom of common bunt is the development of masses of black, powdery teliospores inside the kernels of the infected plant.
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Smutted Kernels: Infected kernels appear normal from the outside, but internally, they contain the teliospore mass. The presence of teliospores gives infected kernels a distinct fishy or foul odor.
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Stunted Seedlings: In some cases, infected seedlings may exhibit stunting, chlorosis, or other abnormal growth patterns.
2. Disease Cycle:
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Infection: The fungus Tilletia tritici infects the host plant during the flowering stage. Infection occurs through the penetration of the floral organs, and the fungus colonizes the developing kernels.
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Teliospore Formation: Inside the infected kernels, the fungus forms teliospores, which replace the normal endosperm.
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Spore Dissemination: When infected seeds are sown, the teliospores are spread, initiating new infections. Additionally, teliospores can be spread by wind or through contaminated farm equipment.
3. Identification:
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Internal Examination: Identification involves opening individual kernels and examining them for the characteristic black spore mass. The fishy odor emitted from infected seeds is also a diagnostic feature.
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Laboratory Analysis: For definitive identification, laboratory analysis may involve extracting and examining teliospores under a microscope.
4. Management:
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Use of Resistant Varieties: Planting wheat varieties with genetic resistance to common bunt is an effective strategy for disease management.
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Seed Treatment: Treating seeds with fungicides can help protect against common bunt. Seed treatments are commonly employed to reduce the risk of introducing the pathogen into new fields.
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Crop Rotation: Implementing a crop rotation strategy can help reduce the inoculum in the soil.
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Hot Water Treatment: Hot water treatment of seeds is an older but effective method to kill the teliospores on the seed surface. This is often used in organic farming or when seed treatments are not employed.
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Sanitation: Removing and destroying infected crop residues and practicing good farm hygiene can help reduce the source of inoculum.
5. Importance:
- Common bunt can lead to significant yield losses and reduce the quality of wheat grains. The foul odor associated with infected seeds makes them unsuitable for milling, and the disease can have economic implications for wheat growers.
