Zinc Deficiency (Khaira) Control

Symptoms

Zinc deficiency, known as khaira disease, usually appears two to four weeks after transplanting. The base of younger leaves shows pale, dusty brown or rusty spots and patches that join into brown streaks, while leaves turn pale green and may bronze. Plants are stunted with delayed and reduced tillering, and severely affected plants stay short with poor, late maturity. It is common on calcareous, alkaline, high pH and continuously flooded soils.

Damage

Stunting, poor tillering and delayed maturity reduce the number of productive tillers and grains, lowering yield. In severe khaira on deficient soils yield loss can be large, and badly affected patches may fail to recover. Because zinc affects early growth, untreated deficiency at the seedling and early tillering stage has lasting effects.

Organic & cultural control

Apply well rotted farmyard manure and compost which improve zinc availability over time. Practise alternate wetting and drying instead of continuous flooding, since standing water lowers zinc availability. Avoid heavy lime and over liming. Maintain organic matter and use green manure. On known deficient soils, plan a corrective zinc application as part of the nutrient programme based on soil testing.

Chemical control

Correct deficiency with zinc sulphate. A common practice is a soil application of zinc sulphate before or at transplanting based on soil test, plus a foliar spray of zinc sulphate with a little lime or urea to quickly green up an affected standing crop. Repeat the foliar spray if symptoms persist. Use soil testing to set the right dose and avoid overuse. Always follow the recommended rate and consult your local KVK or agronomist before applying.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Test the soil and apply zinc sulphate on known deficient fields before transplanting, keep good organic matter, avoid continuous deep flooding by using alternate wetting and drying, and avoid over liming. Watching young plants two to four weeks after transplanting lets you correct khaira early with a foliar spray.