Eyespot

Pseudocercosporella herpotichoides

Pseudocercosporella herpotrichoides is a fungal pathogen that causes the disease known as tan spot in wheat (Triticum aestivum) and other cereal crops. Tan spot is a common foliar disease that can lead to significant yield losses if not properly managed. Here's an informative description of Pseudocercosporella herpotrichoides, covering its appearance, identification, and management:

1. Symptoms:

  • Leaf Lesions: Initial symptoms include the appearance of small, oval to rectangular lesions on the leaves of wheat plants.
  • Lesion Color: Lesions typically have a tan to brown color, surrounded by a yellow halo.
  • Lesion Coalescence: Lesions may coalesce, forming larger necrotic areas on the leaves.

2. Disease Cycle:

  • Infection: The fungus initiates infection through spores (conidia), which are produced on infected plant debris.
  • Spore Dispersal: Conidia are spread by wind or water, leading to the infection of nearby wheat plants.
  • Favorable Conditions: Warm and humid conditions favor the development of tan spot.
  • Survival: The pathogen can survive between growing seasons in infected crop residue.

3. Identification:

  • Lesion Characteristics: Identification often begins with the observation of small, tan to brown lesions with a yellow halo on the leaves.
  • Distinctive Appearance: Tan spot lesions have a distinctive appearance compared to other wheat foliar diseases.

4. Management:

  • Resistant Varieties: Planting wheat varieties that are resistant or less susceptible to tan spot can be an effective strategy.
  • Fungicide Applications: Fungicides, especially those effective against Pseudocercosporella herpotrichoides, can be applied preventively or curatively. Application timing is crucial, and a rotation of different fungicide classes is recommended to reduce the risk of resistance development.
  • Crop Rotation: Avoiding consecutive cultivation of wheat in the same field can help reduce the inoculum in the soil.
  • Cultural Practices: Practices such as proper residue management, avoiding excessive nitrogen fertilization, and providing adequate plant spacing can help create less favorable conditions for disease development.

5. Importance:

  • Economic Impact: Tan spot caused by Pseudocercosporella herpotrichoides can lead to significant yield losses and affect the quality of wheat crops.
  • Global Distribution: The pathogen is present in wheat-growing regions worldwide.