A systematic approach is required in diagnosing nutrient deficiency based on visual symptoms for the following reasons:
1 Nutrient deficiency symptoms are often misdiagnosed as disease caused by pathogens.
2 Diagnosis may be complicated when:
- There is more than one nutrient deficiency
- There is simultaneous deficiency of one nutrient and simultaneous toxicity of another nutrient
- There are damages by pests, disease symptoms, or mechanical injuries including spray damage
3 Nutritional disorders including nutrient deficiencies always have a typical symmetric pattern.
- Leaves of the same or similar position or physiological age on a plant show nearly identical patterns of symptoms
- There is a marked graduation in the severity of the symptoms from old to young leaves
