Bacterial blight of rice, Significance, Distribution, Pathogen character,Mode of spread, Symptoms, Life cycle, Method of control.

1. BACTERIAL BLIGHT OF RICE
COURSE TEACHER
Dr. PARTHASARATHY S
Asst. Professor (Plant Pathology)
STUDENT
MR.ARUNKUMAR M
ID. NO. 2016021004
COLLEGE OF AGRICULTURAL TECHNOLOGY
(Affiliated to Tamil Nadu Agricultural University, Coimbatore3)
Kullapuram (Po),ViaVaigai Dam, Theni-625 562

2. SIGNIFICANCE
• The earlier the diseases occurs the higher the yield
loss.
• Yield loss is as much as 70% when susceptible
varieties are grown in favorable environment.
• Most serious diseases of rice.
• Plants infected at booting stage does not affect their
yield but result in poor quality grains.

3. GLOBAL DISTRIBUTION
• BLB of rice had been known in Japan as an endemic
disease since 1884, later reported in Maharashtra.
• It also occurs in China, Taiwan, Korea, Thailand,
Indonesia, Malaysia, Bangladesh and Australia.
• In Punjab, Haryana and Western Uttar Pradesh major
epidemics occurred in 1979 and 1980.

4. Workers in• Its bacterial nature was established in 1922 in
Ishiyama of Japan.
• In India first authentic report of typical bacterial
blight symptoms was made by Bhapkar and
coworkers in 1960.
• Occurs mostly in high yielding varieties in rainy
season.

5. • The disease was again reported in epidemic form
during 1998 in Pallakad district of Kerala.
• This disease is a major problem in Kharif season
crop.

6. SYMPTOMS
• Leaf blight phase
• Kresek phase
• Pale yellow leaf phase

7. LEAF BLIGHT PHASE
• Water soaked lesions on top of the leaf and increases
in length downwards.
• Lesions are pale green in colour, later turn into yellow
to straw coloured stripes with wavy margins.
• Lesions may start at one or both the edges of the
leaves.

8. KRESEK PHASE
• Also called as wilt phase.
• Resulting from early systemic infection in the nursery
or from seed infection.
• Leafs roll completely, turn yellow or grey and the
tillers wither away.
• In severe cases the affected hills may be completely
killed.

9. PALE YELLOW LEAF PHASE
• This phase of the disease has been reported from
Philippines.
• Youngest leaves in a clump may become pale yellow
or whitish.
• Diseased leaves later wither, turn yellowish brown
and dryup.
• This phase has not been reported from other
countries.

10. www.knowledgebank.irr.org
Bacterial blight of Rice

11. www.knowledge.irr.org
Bacterial leaf blight

12. www.knowledgebank.irri.org
Dried up Bacterial ooze

13. www.slideshare.net
Disease grading

14. www.researchgate.net
Bacterial ooze

15. www.knowledgebank.irri.org
Bacterial ooze

16. agropedia.iitk.ac.in
Kresek

17. SYSTEMATIC POSITION
KINGDOM : Bacteria
PHYLUM : Proteobacteria
CLASS : Gammaproteobacteria
ORDER : Xanthomonodales
FAMILY : Xanthomonodaceae
GENUS : Xanthomonas
SPECIES : X. oryzae pv. oryzae Dye.

18. CAUSAL ORGANISM
• Xanthomonas oryzae pv. oryzae is the causal
organism.
• The bacteria causing the disease are rods, 1.2×0.3-0.5
µm.
• They are single occasionally in chain not in pairs.
• They are gram negative, non-spore forming, rod
shaped bacterium.

19. • They are motile by a single polar flagellum.
• Optimum temperature for growth is 25-30⁰C.
• Thermal death point is 53⁰C.
• Colonies are slow growing and mucoid and straw-
colored to yellow.

20. agritech.tnau.ac.in

21. LIFE CYCLE OF Xanthomonas oryzae
• Plants gets infected with Xanthomonas oryzae
through rice seed, stem and roots that are left behind
at harvest, as well as alternative weed host.
• Upon introduction to the host plants the bacterium
infiltrates the plants through natural openings.
• X. oryzae grows in the plant and infects the plant leaf
veins as well as the xylem causing blockages as the
plant wilting.

22. • Bacterial oozes from leaf lesions and is spread by
wind or rain, especially when strong storms occur and
cause wounds to plants.
• X. oryzae has a wide host range that includes Leersia
sayanuka which act as alternate host for bacterium
and act as a great mechanism for bacterium survival.
• The host includes Cenchrus ciliaris, Cynodon
dactylon, Echinochloa crus-galli, Leersia
oryzoides.

23. MODE OF SURVIVAL
• Bacteria survive in soil only for a short period.
• Survival in soil is based on soil type.
• In acid sulphate and in saline soils survival is less than 10
days.
• The pathogen survives well in alluvial than in black
calcareous or laterite soils.
• In pond water it has been viable for 15-18 days.

24. PRIMARY SPREAD
• Irrigation water contaminated with the bacterium
flowing through field to field.
• Contact of rice leaves with the contaminated water.
• Seed from infected crop.

25. SECONDARY SPREAD
• Secondary spread is brought about through wounds
and stomata.
• The bacterial cell disseminated by wind-borne,
raindrop splashes, by irrigation water or rain water
coming from infested fields and by contact between
diseased and healthy leaves.

26. • The leafhopper (Nephotettix virescens) and the
grasshopper (Hieroglyphus banian) can transmit the
bacterium mechanically on their body.
• The bacteria invade rice plants through hydathodes
on leaves, root growth cracks and wounds.

27. wwwww.plantscience.com
Hydathodes

28. TEST METHODS
• Dipping method
• Guttation method
• Microscopic observation.

29. CULTURE MEDIA
• Potato semi-synthetic agar medium.
• Peptone sucrose agar medium.
• Hayward’s medium.
• Modified wakimoto’s medium .

30. MANAGEMENT
PREVENTIVE METHODS
• Seed soaking for 8 hours in ceresan (0.1%) and treat
with streptocyclin sulphate (3g in 1 litre).
• Spray neem oil 3% NSKE 5%.
• Spray fresh cowdung extract.

31. CULTURAL METHODS
• Grow tolerant varieties.
• Tolerant varieties in Tamil Nadu are ADT 36, ADT
39, CO 45, Karaikalan, Karuna, Vaigai.
• Tolerant varieties in Kerala are Neerya 11525,
Pavizham 8132.
• Tolerant varieties in Andra Pradesh are Apurna, Indra,
Mahsuri, Swarna, Tholakari, Tikkara.

32. • Avoid clipping of seedling during transplanting.
• Avoid excess nitrogen application.
• Destruction of weeds and collateral hosts.
• Maintain proper plant spacing.

33. CHEMICAL METHODS
• Spray streptomycin sulphate+Tetracycline
combination 300 g +copper oxychloride 1.25kg/ha.
• Application of bleaching powder at 5kg/ha in the
irrigation water is recommended at the kresek stage.

34. REFRENCES
• Singh.R.S, Plant Disease, Oxford & IBH Publishing
Company, New Delhi 110049. pp160-164.n
• Singh.R.P, 2018. Plant Pathology, Kalyani publishers,
New Delhi-110002.pp326-332.y, New Delhi 110
049. pp 264-268

35. THANK YOU