Sheath Blight of Rice: Causes, Symptoms, and Management Strategies

 

Disease Overview :

• Disease Name: Sheath Blight
• Causal Organism: Rhizoctonia solani (fungus)
• Affecting Stage: Primarily affects the crop from the tillering to milk stage

Symptoms :

1. Initial Symptoms: Elliptical or irregular, greenish-grey water-soaked lesions on the leaf sheaths near the waterline.
2. Lesion Expansion: Lesions expand, turning greyish-white with brown margins.
3. Disease Progression: The disease progresses upward, covering the entire leaf sheath and sometimes the leaf blades

Favorable Conditions :

1. High Relative Humidity: 80% or more
2. Temperature: 28-32°C
3. Excessive Nitrogen Fertilizers: Dense planting and close spacing
4. Continuous Water Stagnation: Poor drainage
5. Cloudy and Rainy Weather: During the vegetative and reproductive stages

Control Measures :

Cultural Control –

Use resistant varieties (e.g, Pusa Basmati 1121, MTU 7029), avoid overcrowding, balanced fertilization, ensure good drainage

Organic Control –

Trichoderma harzianum, neem cake, neem oil, garlic extract

Chemical Control –

Validamycin 3% L (@2ML/lit of water) , Hexaconazole 5% SC  (@2ml/lit),  Propiconazole 25% EC (@1ml/lit), Azoxystrobin 23% SC (@1ml/lit).

Trade Names of Chemicals :

1. Validacin: Validamycin 3% L (Tata Rallis)
2. Contaf: Hexaconazole 5% SC (Tata Rallis)
3. Tilt: Propiconazole 25% EC (Syngenta)
4. Amistar: Azoxystrobin 23% SC (Syngenta)

Effective Management :

By implementing these control measures, farmers can reduce the risk of sheath blight and improve rice yields.