This document summarizes information about bacterial leaf blight and khaira disease of rice. Bacterial leaf blight is caused by the bacteria Xanthomonas campestris and has several symptoms including leaf blights, wilting, and yellowing. Khaira disease is caused by zinc deficiency and shows symptoms like reddish-brown speckling on leaves. Management of these diseases involves practices like removing plant debris, using resistant varieties, spraying antibiotics, and applying zinc to soils or seedlings.

1. • COURSE NO.- APP 312
• COURSE TITLE- DISEASE OF FIELD AND HORTICULTURE CROP
• CREDIT HRS- 3(2+1)
• TOPIC- Bacterial leaf blight and Khaira disease of Rice .
• Name- Suman Kumar Surendra Respt.Dr. Santoshkumar
• Roll no.- MBAC/15/2016-17
AGWANPUR, SAHARSA
Submitted by Submitted to

2. BACTERIAL LEAF BLIGHT OF RICE
Pathogen : Xanthomonas campestris p. var. oryzae
Class : Schizomycetes
Order: Pseudomonadales
Family : Pseudomonadaceae

3. • History :
It was 1st reported in Japan during 1884 & in
India during the year 1951 in Maharashtra.
In India BLB was first described by Srinivasan et al. from
Pune in 1959.
Introduction of rice variety TN-1 in India the disease
spread rapidly due to its susceptibility.
 Later on,in 1962 the disease broke out in the
form of epidemics in Bihar and other parts of North India.
Now this disease is found to be prevalent non traditional
rice growing areas of Punjab and Haryana.

4. Etiology
• The bacteria is rod-shaped measuring
1 to 2 X 0.5 to 0.8 μm. They occur singly or in
pairs. They are Gram –ve , aerobic and with a
single polar flagellum. They are non-spore forming
and do not form chains. Bacterial cells are surrounded by
mucus by capsule which is a kind of heteropolysaccharides
Called xanthomonadin.
•Two pathotype reported in India.

5. • The disease appears early in August and becomes quite
distinct when the ears developed.
• The symptoms of the disease may vary depending upon
growth stage of the crop.
There are 3 types of symptoms
Leaf blight
Kreseck /wilt
Yellow leaf

6. • Leaf blight :-
This symptoms will appear 4-6 weeks after transplanting.
Appearance of small circular water soaked spot on the margins
of the leaf & this spots also extends to leaf sheath, also later this
spots turn yellow & becomes necrotic & results in drying of
leaf.

7. • Kreseck / wilt :-
this is the most destructive stage & Kreseck degenerations /
wilting. Young plants are more susceptible which shows sudden
wilting. The bacteria multiplies in vascular bundles , exudation
of bacterial ooze at the cut end portion of leaf.

8. • Yellowing stage :
Here individual leaf becomes yellow later wilting & dies.

9. Predisposing factors:-
Rainy weather, dull windy days and a suitable temperature of
22 ̊c to 26 ̊c, clipping of tip of leaves of seedling during
transplanting , excess application of nitrogenous fertilizer
favour the incidence of the disease.
Disease cycle:-
•The blight disease of rice is a vascular disease .
•PSI:-
•The primary infection stubbles or on overlapping crops .
•It may be survive in soil.
•The primary inoculums may also built up from soil or plant
stubbles and debris and can infected nursery seedling .
•The bacterium infected some grasses like leersia spp .which
may play role spread of pathogen.
•SSI:-
•It disseminated through irrigation water and air borne rain .

10. Infection:-
• Infection takes place through wounds.
•It also enters through roots stem near ground or
hypothodes in leaves.
•After infection it become systemic in the vascular bundle
and move upward .

12. Management:-
• Removal, collection and burning of diseased plant parts
straw left over in the field after harvest.
• Burning of chaffy grains near the threshing yard.
• Irrigation canal, paddy field should be kept free from weed
avoid movement of irrigation water from field to field.
• Selection of healthy seeds for sowing.
• Avoid clipping of tip of the leaves.
.

13. • Judicious use of nitrogenous fertilizer.
• Growing of resistant varieties Swarna, Ajay, IR20.
• Spraying of the crop with streptomycin @ 0.6 g/litre.
•A mere soaking of seed for 8 hours in cerseson (0.1%) and
streptacycline –crude agriculture preparation (3g in 1100litre
of water ) followed by hot water treatment at 52-54 C for 10
minute is effective to eradicate the disease.
•Spraying with copper fungicide alternatively with
streptocycline (250ppm) after 30 days of transplanting

15. Causal agent:
• This disease occurs due to zinc deficiency.
• It is a non-parasitic and non-infectious disease.
History:
• First diagnosed in rice (Oryza sativa) on calcareous
soils of Tarai region of Uttar Pradesh of India (Nene,1966).
• Widespread phenomenon in lowland rice growing
areas of Asia, next to nitrogen (N) and phosphorus (P)
deficiency.
• Yield loss may upto 25%.

16. Distribution:-
• Neutral and calcareous soils.
• Intensively cropped soils.
• Poorly drained soils.
• Coarse textured soils.
• Soils with high available Phosphorus (P) and Silicon (Si)
status.
• Soils with a small concentration of Potassium (K),
Magnesium (Mg) and Calcium (Ca).

17. Role of zinc in plants:
• Zinc is an essential plant nutrient required for several
biochemical processes in the rice plant, including
chlorophyll production and membrane integrity.
• Zn deficiencies affect plant colour and turgor.
• Zn is only slightly mobile in the plant and quite
immobile in soil.
•Zn catalyze the enzymatic activities & oxidation reduction
reaction.

18. Favourable conditions:-
• Small amount of available Zn in the soil.
• Plants varieties are susceptible to Zn deficiency
(i.e., Zn-inefficient cultivars).
• Zn is precipitated as sparingly soluble Zn(OH)2 when
pH increases in soil.
• Depressed Zn uptake because of an increase in Fe,
Ca, Mg, Cu, Mn and P contents in soil after flooding

19. • Formation of Zn-phosphates when large applications
of phosphatic fertilizer.
• Formation of complexes between Zn and organic
matter in soils because of large applications of
organic manures and crop residues.
• High magnesium (Mg) to Calcium (Ca) ratio.

20. Symptoms:-
• Symptoms appear both in
 Nursery :-Seedling stage – 10-15 DAS and
 Main Field:- between two to four weeks after
transplanting.
Initial identification:-
•Third leaf counting from top which characterised by
reddish brown speck after severity these speck collides to
form a big patch and its colon resembles with catechu i.e.
khair so it named as khaira disease .

21. Field view:

22. Increased spikelet sterility in rice.
 Chlorotic midribs, particularly near the leaf base of
younger leaves.
 Leaf blade size is reduced

23. Distribution:-
• Neutral and calcareous soils.
• Intensively cropped soils.
• Poorly drained soils.
• Coarse textured soils.
• Soils with high available Phosphorus (P) and Silicon
(Si) status.
• Soils with a small concentration of Potassium (K),
Magnesium (Mg) and Calcium (Ca).

24. Management:
• Grow Zn-efficient varieties.
• Use fertilizers that generate acidity (e.g., replace
some urea with ammonium sulphate).
• Apply organic manure before seeding in nursery or
transplanting of rice in main field.
• Monitor irrigation water quality.

25. Broadcast ZnSo4 in nursery seedbed 5 days before
pulling out of seedlings.
• Dip seedlings or pre-soak seeds in a 2−4% ZnO
suspension.
• Zinc sulphate 25-30 kg/ha as soil application at the
time of puddling.
• Mix 5 kg ZnSo4 + 2.5 kg slaked lime + 1000 litters
water and sprayed it on 10 and 20 days after sowing
in nursery.