Spot blotch

Causal Agent:

• Spot Blotch is primarily caused by the fungus Bipolaris sorokiniana (formerly known as Helminthosporium sativum).

Host:

• The major host for Spot Blotch is wheat (Triticum aestivum).

Symptoms:

1. Leaf Lesions: Initial symptoms appear as small, oval to elongated lesions on the leaves.
2. Dark Brown to Black Color: Lesions typically have a dark brown to black color with a tan center.
3. Lesion Enlargement: Lesions may enlarge and coalesce, forming irregularly shaped spots on the leaves.
4. Yellowing and Necrosis: Surrounding the lesions, there is often yellowing of the leaf tissue, and severe infections can lead to necrosis.
5. Lesions on Sheaths and Nodes: In addition to leaves, lesions can also occur on sheaths and nodes, affecting overall plant health.

Identification:

1. Distinctive Lesions: Recognize the characteristic dark lesions on leaves, which distinguish Spot Blotch from other wheat diseases.
2. Lesion Distribution: Lesions are often distributed across the leaves in a scattered pattern.

Disease Cycle:

1. Overwintering: The fungus can overwinter on infected plant debris or seeds.
2. Spore Production: Spores (conidia) are produced on infected residues or plants.
3. Infection: Spores are disseminated by wind or rain to healthy plants, initiating new infections.

Management:

Cultural Practices:

1. Resistant Varieties: Planting wheat varieties with resistance or tolerance to Spot Blotch can be an effective strategy.
2. Crop Rotation: Rotate crops to break the disease cycle and reduce inoculum in the soil.
3. Timely Planting: Planting at the optimal time can help avoid conditions favorable for disease development.

Fungicide Application:

1. Foliar Fungicides: Application of fungicides, especially during critical growth stages, can help manage Spot Blotch.

Regular Monitoring:

1. Scouting for Symptoms: Regularly monitor wheat crops for early symptoms of Spot Blotch, especially during periods conducive to disease development.