Sheath blight, caused by the fungus Rhizoctonia solani, is a major disease of rice. It was first reported in Japan in 1910 and causes significant yield losses, ranging from 5-50% depending on location and cultivar. Symptoms include oval to elliptical greenish-grey lesions on rice sheaths and leaves. Favorable conditions for disease development are high humidity, temperatures between 28-32°C, and frequent rainfall. Integrated management strategies include cultural practices like removing weeds and crop debris, using resistant varieties, and chemical control with fungicides. Biological control with antagonistic microorganisms like Pseudomonas fluorescens can also help reduce sheath blight severity.

1. SHEATH BLIGHT OF RICE
COLLEGE OF AGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore-3)
Kullapuram (Po),ViaVaigai Dam, Theni-625 562
STUDENT
Miss. ABIRAMI.C
ID. No. 2015021003
COURSE TEACHER
Dr. PARTHASARATHY S
Asst. Professor (Plant Pathology)

2. RICE SHEATH BLIGHT / BANDED LEAF BLIGHT
CAUSAL ORGANISM
 Anamorph - Rhizactonia solani (Julius Kuhn)
 Telomorph - Thanatephororus cucumeris (A.B Frank.Donk)

3. HISTORY
• Disease was first recorded in Japan( Miyake, 1910).
• In India, the disease was first reported from Gurudasar,
Punjab (Paracer and Chahal, 1963).
• Later it was first reported from Uttar Pradesh
(Kohli , 1996).
• Estimates of yield reduction due to sheath blight have
been reported ranging from 5.2 to 6.9 % (Hori 1969;
Kannaiyan and Prasad 1978; Naidu 1992).

4. • Rice sheath blight / Banded leaf blight
• Vernacular name – Snake skin disease
• When several such lesions are developed continuously on a
greenish tissue, it almost looks like a snake skin from a
distance and so it is called by the farmers as snake skin
disease.
• Local Kannada name – Yele Kavachada Machee Roga

5. SYSTEMATIC POSITION
• Domain - Eukarya
• Kingdom - Fungi
• Phylum - Basidiomycota
• Class - Agariomycetes
• Order - Cantharellales
• Family - Certobasidiaceae
• Genus - Thanatephorus
• Species - T. cucumeris

6. ECONOMIC IMPORTANCE
 In Japan, the disease caused a yield loss of as high as 20%
and affected about 12,000 – 1,90,000 hectares.
 A yield loss of 25% was reported if the flag leaves are
infected.
 In the United States, a yield loss of 50% was reported
when susceptible cultivars were planted. Studies at IRRI
showed that sheath blight causes a yield loss of 6% in
tropical Asia.

7. OCCURRENCE IN WORLD
 United states of America
 Tropical Asia
 Australia
 Phillipines

8. OCCURRENCE IN INDIA
• The sheath blight appeared in moderate to severe intensity
in a few states like
 Andra Pradesh,
 Kerala,
 Orissa,
 West Bengal.

9. SYMPTOMS
• Symptoms appear from tillering to heading stage.
• Lesions appear on sheaths on lower leaves near the water
line.
• Lesions appear on leaf collar oval to elliptical greenish
grey water soaked spots ¼ inch wide, ½ to 1 ¼ inch long.
• During favourable condition, lesions enlarge forming
irregular shaped lesions with greyish white centres with
dark brown borders.

10. • The infection extends to the inner sheaths resulting in
death of the inner sheath resulting in death of the entire
plant.
• Five to six week old leaf sheaths are highly susceptible.
• The presence of several large lesions on leaf sheath usually
cause death of the whole leaf and in severe cases all the
leaves of a plant may be blighted.

11. SYMPTOMS
© agritech.tnau.ac.in
©agritech.tnau.ac.in

12. FAVOURABLE CONDITIONS
• High infection at 100% RH.
• High temperature (28 – 32◦ C).
• Frequent rainfall favours disease development.
• High dose of nitrogen.
• Close planting favours pathogen attack.
• High seed rate.

13. MODE OF INFECTION
 Primary spread of disease - all grasses, broad leaved weeds
grown on rice bunds produce similar symptoms and
producing sclerotial bodies.
 Sclerotial bodies fall in paddy water and initate infection
on rice crop.
 Secondary spread of infection - Seed borne, wind borne
and water borne disease.

14. PATHOGEN CHARACTERS
• Fungus produce usually long cells of septate mycelium
which are hyaline when young, yellowish brown spherical
when old.
• Individual sclerotia are 1-3mm in diameter. Sclerotia are
formed on or near the spots and can be easily detached
from the plant.
• Pathogen survive as sclerotia in dry soil for 20 months but
for 5 to 8 months in moist soil.

15. © agritech.tnau.ac.in
LIFE CYCLE
LILLKDJDNS
DN

16. © https://www.slideshare.net/FOODCROPS/yongi-screening-for-
resistance-to-rice-disease

17. MYCELIUM OF
Rhizoctonia solani
BASIDIOSPORE OF
Rhizoctonia solani
© https:ww.cals.ncsc.edu

18. INTEGRATED DISEASE MANAGEMENT
CULTURAL METHODS
Avoid closer spacing.
Use moderately resistant varieties like Swarauhan,
Pankaj, Mansarovar and Radha etc.,
Split application of nitrogen ferilizer.
Deep ploughing in summer.
Burning of stubbles.
 Eliminate weed host.

19. CHEMICAL METHODS
• Seed treatment with Carbendazim 2 g/ kg of seeds.
• Hexaconazole 75% WP @ 1 00 mg / litre 1st spray at the
time of disease appearance and 2nd spray 15 days after
first spraying.
• Spraying of Chlorothalanil 1 Kg or Edifenphos 1 lit/ ha.
• Spraying of Carbendazim ( 1g /lit), Propiconzole
(1 ml/lit)may be applied.
• Spray Validamycin 3 L @ 2.5 ml / litre of water or
Thifluzamide 24 EC@ 1 ml/lit of water.

20. BIOLOGICAL METHODS
 Antogonist micro- organisms fluorescent bacteria were
isolated that showed high level of antogonism against
sheath blight pathogens.
 Foliar spray with Pseudomonas fluorescens TNAU P.f 1
liquid formulation @ 5 ml / ha.
 Seed treatment with P. fluorescens @ 10 g/kg of seed.

21.  Soil application of Pseudomonas fluorescens @ 2.5 Kg /
ha was mixed with 50 kg of FYM / 50 kg of fine Sand.
 Seedling dip P.fluorescens @ 2.5 kg product / ha in 100 lit
of water for 30 minutes.
 In Rajashahi, press – mud, saw dust and rice bran reduced
disease severity.

22. REFERENCES
• www.knowledgebank.irri.org
• agropedia.iitk.ac.in
• agritec.tnau.ac.in