Barley leaf scald

Causal Agent: Rhynchosporium secalis is a fungus responsible for causing scald, a common foliar disease in cereal crops, particularly barley (Hordeum vulgare).

Symptoms:

1. Leaf Lesions:

   • Oval Lesions: The characteristic symptoms include the development of oval-shaped lesions on the leaves.
   • Gray to Tan Centers: Lesions have gray to tan centers with a dark border, giving them a distinctive appearance.

2. Leaf Blighting:

   • Severe Infections: In severe cases, the lesions coalesce, leading to widespread blighting of the leaves.
   • Reduced Photosynthesis: Extensive leaf damage can impact the plant's ability to photosynthesize.

3. Culm and Sheath Infections:

   • Lesions on Culms and Sheaths: While the primary impact is on leaves, culms (stems) and sheaths may also become infected, affecting the overall health of the plant.

Identification:

1. Distinctive Lesions:

   • Oval-shaped lesions with gray to tan centers and dark borders on leaves, culms, and sheaths.

2. Favorable Conditions:

   • Humidity and Rain: The disease tends to thrive in humid conditions, and rain can facilitate spore dispersal.

Conditions Favoring Disease:

1. Humid Conditions:

   • Moisture Facilitates Spore Production: Rhynchosporium secalis produces spores in the presence of moisture, and high humidity favors disease development.

2. Moderate Temperatures:

   • Optimal Growth Conditions: Moderate temperatures, typically ranging from 15 to 25 degrees Celsius (59 to 77 degrees Fahrenheit), are conducive to the growth of Rhynchosporium secalis.

Management:

1. Resistant Varieties:

   • Plant Resistant Cultivars: Utilize barley varieties that exhibit resistance or tolerance to Rhynchosporium secalis.

2. Fungicides:

   • Foliar Applications: Application of fungicides may be considered in cases of severe infections. Consult with local agricultural extension services for appropriate recommendations.

3. Crop Rotation:

   • Reduce Inoculum Buildup: Practice crop rotation to reduce the buildup of the pathogen in the soil.

4. Sanitation:

   • Remove Infected Debris: Promote sanitation by removing and destroying infected plant debris.

Note: Scald caused by Rhynchosporium secalis can lead to significant yield losses in barley crops. Integrated disease management strategies, including resistant varieties, fungicides, and cultural practices, are crucial for effective control.