Tan spot

Pyrenophora tritici-repentis is a fungal pathogen that causes tan spot, a common foliar disease affecting wheat crops. Here's an informative description:

Symptoms:

1. Lesions: Circular to oval-shaped lesions with tan centers and yellow to brown borders appear on the leaves.
2. Necrosis: Lesions may expand, leading to necrosis and blighting of the affected leaves.
3. Spore Production: The fungus produces dark, elongated, and lens-shaped structures (pycnidia) within the lesions.

Identification:

1. Lesion Appearance: Identify lesions with characteristic tan centers and distinct borders.
2. Pycnidia Presence: The presence of dark pycnidia within the lesions is a diagnostic feature.

Disease Cycle:

1. Survival: The fungus can survive in infected crop residues.
2. Spore Production: Pycnidia produce conidia, which are spread by wind and rain to new plants.
3. Infection: Conidia can germinate and infect wheat leaves, initiating new infections.

Management:

Cultural Practices:

1. Residue Management: Manage and incorporate crop residues to reduce the survival of the pathogen.
2. Crop Rotation: Rotate crops to break the disease cycle and reduce inoculum in the soil.

Fungicide Application:

1. Foliar Fungicides: Application of fungicides during the growing season, especially at critical stages, can help manage tan spot.

Regular Monitoring:

1. Field Scouting: Regularly monitor wheat fields for early symptoms of tan spot, especially during periods conducive to disease development.

Resistant Varieties:

1. Choose Resistant Varieties: Plant wheat varieties that are resistant or less susceptible to tan spot.