Symptom differential
Purple or Red Pigmentation
Anthocyanin-related purple or red coloration can be genetic or developmentally normal, and can also increase with temperature, nutrient, root, or other stress. Pigment color alone is not a deficiency diagnosis.
Pattern questions
- Is the cultivar known for pigmentation?
- Are leaves otherwise healthy and growing normally?
- Did cool temperatures precede the change?
- Are petioles, stems, veins, or whole leaves affected?
Plausible cause categories
- Genetic anthocyanin expression
- Cool-temperature response
- Developmental senescence
- Nutrient or root-zone stress
- High-light protective response
Discriminating checks
- Compare with cultivar baseline
- Review temperature history
- Inspect roots and growth rate
- Check whether other stress symptoms are present
Red flags
- Pigmentation with severe stunting
- Concurrent necrosis
- Root decline
- Rapid unexplained progression
Visual study guide
- Genetic pigmentation examples
- Petioles-versus-leaf pigmentation
- Cool-temperature context
- Pigment-plus-stress differential