Sheath blight: Rhizoctonia solani Kuhn.(Deuteromycotina: Mycelia Sterilia)

Local name: Yele Kavachada Macchhe Roga

Vernacular Name: Snake skin disease

• Sheath blight is a fungal disease, more common in rainy season than in dry season in the topics.
• This disease is problematic in areas where irrigation facilities are abundant.
• Due to blighting of the leaf sheaths, it is commonly called as sheath blight.

Period of occurrence: Tillering to milk stage

Extent of yield loss: On an average, 20 to 50% annual yield loss

Alternate hosts: Among the plants recorded as hosts are, sugarcane, bean, soybean, tomato, egg plant, tobacco, water hyacinth , hyacinth bean and green gram

Favourable conditions for the pathogen:

• High temperature (28-32°C)          
• High relative humidity (>96%)                     
• Frequent rainfall
• High doses of N
• Close planting

                        

Mode of transmission/dissemination: Seed, Soil, Wind, and Water.

Sources of inoculum: Sclerotial bodies left in the field from previous crop and weeds, Mycelium in the plant debris.  

Damage symptoms:

• Appearance of one or more relatively large, oblong or irregularly elongated lesions on the leaf sheath; in advanced stages center of the lesion becomes bleached with an irregular purple brown border.
•  Initially these lesions are white in colour later it turns to dark brown.
• At severe condition drying of leaves.

            

Management

 Cultural Practices:

• Moderately Resistant Varieties: Swarnadhan, Vikramarya, Radha, Pankaj, Manasarovar, Mandya Vijaya.  
• Avoid using infected seed. 
• Apply moderate 'N' levels (80-100 kg/ha) in 3-4 splits. 
• Avoid excess 'N', skip final 'N' in sheath blight infected fields. 
• Destroy stubbles / weeds, etc. 
• Check brown plant hopper population 

Chemical control

• 1g of carbendazim 50 WP(540g/acre) or 2g mancozeb 75 WP in 1 liter of water.
• Seed treatment with carendizm 2.0g/kg of seeds.
• Spraying fungicides of 1g carbendazim 50WP (540g/acre) or 2.0g mancozeb 75WP OR 1ml hexaconozole in 1 liter of water.

Source: UASD, DRR & UASB Package of practice