Diagnostic Guide: Location & Visual Symptoms
Yellowing of foliage (chlorosis) represents the loss or breakdown of chlorophyll. Mistaking a nutrient deficiency for a fungal disease leads to unnecessary pesticide expenditure while failing to address root nutrition.
| Symptom Pattern | Leaf Position | Probable Cause | Corrective Formulation |
|---|---|---|---|
| Uniform pale yellowing across entire leaf | Older (lower) leaves | Nitrogen (N) Deficiency | Foliar 1-2% Urea spray or top dressing |
| Interveinal chlorosis (veins stay green) | Older (lower) leaves | Magnesium (Mg) Deficiency | Magnesium Sulphate (MgSO4 @ 1%) foliar |
| Interveinal chlorosis progressing to ivory white | Younger (top) leaves | Iron (Fe) Deficiency | Ferrous Sulphate (0.5%) + Citric acid (0.1%) |
| Bronzing and white bleaching of midrib | Middle to young leaves | Zinc (Zn) Deficiency (Khaira) | Zinc Sulphate (0.5%) + 0.25% Slaked lime |
| Mosaic yellow-green mottling with stunted leaves | All foliage | Viral Disease (YVMV / Mosaic) | Vector control (Acetamiprid 20 SP @ 0.3g/L) |
Crop-Specific Symptoms: Paddy, Wheat & Tomato
In Paddy: Khaira disease caused by Zinc deficiency appears 2 weeks after transplanting with reddish-brown pigmentation. Spray Zinc Sulphate @ 5 kg + Lime 2.5 kg in 1000L water per hectare.
In Wheat: Nitrogen deficiency causes V-shaped yellowing starting from leaf tips on lower canopies.
In Tomato: Early blight (Alternaria solani) causes concentric target-board ring spots, unlike nutritional yellowing.
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