Khaira disease of rice is caused by zinc deficiency in the soil. It occurs on calcareous soils that have low zinc availability. Symptoms include dusty brown spots on leaves, stunted growth, and reduced fertility. Yield losses can be up to 25%. Management strategies include using zinc-efficient varieties, applying organic matter and zinc sulfate fertilizer to increase soil zinc levels, and acidifying the soil to improve zinc availability.

1. KHAIRA DISEASE OF RICE
STUDENT COURSE TEACHER
Krishna Kumar.R.V Dr.Parthasarathy.S
ID.NO:2015021066 Asst.Prof.,(Plant Pathology)

2. Disease Name:
Khaira disease of rice.
Causal agent:
• This disease occurs due to zinc deficiency.
• It is a non-parasitic and non-infectious disease.

3. 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%.

4. 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).

5. 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 color and turgor.
• Zn is only slightly mobile in the plant and quite
immobile in soil.

6. Favorable 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.

7. • 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.

8. Symptoms:
• Symptoms appear both in nursery and in mainfield
between two to four weeks after transplanting.
• Dusty brown spots on upper leaves of stunted plants.
• Uneven plant growth.
• Patches of poorly established hills in the field.

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

10. Symptoms:
TNAU Agritech Portel

11. Field view:

12. TNAU Agritech Portel

13. 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 mainfield.
• Monitor irrigation water quality.

14. • Broadcast ZnSo4 in nursery seedbed 5 days before
pulling out of seedlings.
• Dip seedlings or presoak 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 liters
water and sprayed it on 10 and 20 days after sowing
in nursery.