Sheath Blight in Paddy Crops: Symptoms, Causes, Management Strategies

• September 06 2023, by Agriplex India
• 6 min reading time

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Paddy, also known as rice, is one of the world's most vital staple crops, feeding billions of people worldwide. However, paddy cultivation faces numerous challenges, with sheath blight disease being a significant threat. Sheath blight, caused by the fungus Rhizoctonia solani, can devastate paddy fields if not effectively managed. In this blog, we will explore the symptoms, factors responsible for its occurrence, and strategies for its control.

Table of Contents:

1. Symptoms of Sheath Blight in Paddy Crops
2. Factors Responsible for Sheath Blight
3. How to Control Sheath Blight
4. Frequently Asked Questions (FAQs)

1. Symptoms of Sheath Blight in Paddy Crops

Recognizing the symptoms of sheath blight is crucial for early detection and control. Here are the key indicators of this devastating disease:

• Lesions on Leaf Sheaths: The most noticeable symptom of sheath blight is the presence of irregular, water-soaked lesions on the leaf sheaths. These lesions are initially small and white, but they gradually expand and turn brown as the disease progresses.

• Wilting and Drooping Leaves: Infected paddy plants often exhibit wilting and drooping of their leaves, making them appear unhealthy and stressed.

• White Mycelial Growth: In humid conditions, white, cottony mycelial growth can be observed on the affected leaf sheaths and blades. This mycelial growth is a key diagnostic feature of sheath blight.

• Leaf Blade Necrosis: As the disease advances, the leaf blades may also show signs of necrosis, further reducing the plant's ability to photosynthesize and produce grains.

• Panicle Sterility: Severe sheath blight infections can lead to panicle sterility, resulting in reduced grain production.

2. Factors Responsible for Sheath Blight

Understanding the factors that contribute to sheath blight is essential for effective management. Several factors play a role in the development of this disease:

• Fungal Pathogen: The primary cause of sheath blight is the fungus Rhizoctonia solani. This pathogen thrives in warm and humid conditions, making paddy fields in tropical and subtropical regions particularly susceptible.

• Environmental Conditions: High humidity, prolonged leaf wetness, and temperatures between 25°C to 30°C provide ideal conditions for the growth and spread of Rhizoctonia solani.

• Varietal Susceptibility: Some paddy varieties are more susceptible to sheath blight than others. It's crucial to select resistant or tolerant rice varieties when planting.

• Crop Density: Overcrowding and excessive planting density can create a microenvironment conducive to the development and spread of sheath blight.

• Poor Drainage: Inadequate field drainage can lead to stagnant water, creating a favorable environment for the fungus to thrive.

3. How to Control Sheath Blight

Effective control measures are essential to manage sheath blight and minimize yield losses. Here are some strategies to combat this disease:

• Crop Rotation: Rotate paddy with non-host crops like wheat or legumes to disrupt the pathogen's life cycle and reduce its prevalence in the field.

• Resistant Varieties: Choose paddy varieties that are resistant or tolerant to sheath blight. Consult local agricultural experts or research institutions for recommendations on suitable varieties for your region.

• Proper Spacing: Avoid planting paddy too densely. Adequate spacing between plants can improve air circulation and reduce humidity in the canopy, making it less favorable for the fungus.

• Fungicides: When the disease pressure is high, fungicides can be used as a preventive or curative measure. Consult with agricultural experts or extension services for guidance on appropriate fungicides and application timings.

Here are the top Chemical Fungicides used for the control of Sheath Blight in Paddy

1) Saaf - UPL Saaf is a systemic and contact fungicide that provides broad-spectrum control of a wide range of fungal diseases. It contains Carbendazim 12% and Mancozeb 63% WP

2) Nativo - Bayer Nativo is a systemic and contact fungicide. It is  a combination of two active ingredients: tebuconazole and trifloxystrobin

3) Bavistin - Crystal Crop Bavistin Fungicide is a broad-spectrum systemic fungicide that is effective against a wide range of fungal diseases. It contains Carbendazim 50% DF

4) Blue Copper- Blue copper is a copper-based broad-spectrum fungicide that controls fungal as well as bacterial diseases by its contact action.

5) Blitox - Tata Blitox Fungicide is a broad-spectrum contact fungicide that contains Copper Oxychloride 50% WP. It is a foliar-applied product that can be used on a variety of crops

For all Fungicide applications, always mix stickers  like Maxiwet or Stickmax for better absorption by the plants

• Biological Control: Explore the use of biological control agents such as Trichoderma spp. or bacterial antagonists to suppress the growth of Rhizoctonia solani. The best biological fungicide for control of Sheath Blight is multiplex Bio-Jodi

• Pruning and Sanitation: Remove and destroy infected plant material to prevent the spread of the disease within the field.

• Proper Irrigation and Drainage: Ensure that fields have proper irrigation and drainage systems to prevent water stagnation, which creates a conducive environment for the pathogen.

• Timely Harvest: Harvest paddy crops at the appropriate maturity stage to minimize disease spread during harvesting and threshing.

4. Frequently Asked Questions (FAQs)

Q1: Can sheath blight be completely eradicated from paddy fields? A1: Complete eradication of sheath blight may be challenging, but it can be effectively managed through proper cultural practices and the use of resistant varieties and fungicides.

Q2: Are there any organic methods to control sheath blight? A2: Yes, organic methods like biological control agents (e.g., Trichoderma spp.), crop rotation, and maintaining proper field hygiene can help control sheath blight without synthetic chemicals.

Q3: How can I identify sheath blight in its early stages? A3: Look for small, water-soaked lesions on the leaf sheaths, wilting leaves, and white mycelial growth on affected plant parts. Early detection is key to effective control.

Q4: Is sheath blight contagious? A4: Sheath blight can spread within a paddy field but is not typically considered highly contagious between fields.

Q5: What are the economic impacts of sheath blight on paddy production? A5: Sheath blight can significantly reduce paddy yields, leading to economic losses for farmers. The severity of the impact depends on the disease's prevalence and management practices.

In conclusion, sheath blight is a persistent threat to paddy crops worldwide, but with proper management strategies, it can be controlled. By recognizing the symptoms, understanding the contributing factors, and implementing effective control measures, farmers can safeguard their paddy fields and ensure a healthy and productive harvest. Sustainable agricultural practices and the use of resistant varieties can play a vital role in mitigating the impact of sheath blight on paddy production.

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Agriculture Blogs Gallery Diseases Early Blight Farming Late Blight Paddy Sheath Blight Soil Testing

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