Black scurf

Causal Agent: Rhizoctonia solani is a fungal pathogen that causes a variety of plant diseases, collectively known as Rhizoctonia diseases. It affects a wide range of crops, ornamental plants, and turfgrasses.

Symptoms:

1. Damping-Off:

   • Seedlings: Causes damping-off of seedlings, leading to rotting of the base of the stem at soil level.

2. Root Rot:

   • Roots: Induces root rot, causing dark, sunken lesions on the roots and lower stem.

3. Leaf Spot:

   • Leaves: Causes irregular, dark lesions on leaves.

4. Sheath Blight:

   • Grasses: In turfgrasses, it can cause sheath blight, characterized by irregular, brown lesions on grass blades.

5. Stem Cankers:

   • Stems: Formation of cankers on stems, often leading to girdling and wilting.

Identification:

1. White Mycelium:

   • Presence of white, cottony mycelium on infected plant parts, particularly during high humidity.

2. Sclerotia:

   • Formation of dark, compact structures called sclerotia, which can survive adverse conditions.

3. Disease Patterns:

   • Variable disease patterns depending on the host and environmental conditions.

Hosts: Rhizoctonia solani has a broad host range and can infect various plants, including vegetables, ornamentals, cereals, and turfgrasses.

Favorable Conditions:

1. Warm Temperatures:

   • Optimal Growth: Favors disease development in warm temperatures.

2. Moisture:

   • High Humidity: Provides conditions conducive to the formation and spread of mycelium.

Management:

1. Crop Rotation:

   • Practicing crop rotation helps reduce the buildup of the pathogen in the soil.

2. Resistant Varieties:

   • Planting crop varieties resistant or tolerant to Rhizoctonia solani can be an effective strategy.

3. Seed Treatment:

   • Treating seeds with fungicides can prevent damping-off in seedlings.

4. Soil Fungicides:

   • Application of soil fungicides, especially in high-risk situations, can help manage the disease.

5. Proper Irrigation:

   • Avoid overwatering and ensure proper drainage to minimize conditions favorable for disease development.

Note: Rhizoctonia solani can persist in soil and plant debris for extended periods, making it important to implement integrated management practices. Monitoring and early intervention are crucial for minimizing the impact of Rhizoctonia diseases on crops and plants.