causal organism, history, distribution,symptoms,life cycle,Integrated Disease Management

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
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©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
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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