# Necrosis

> Death of plant tissue, seen as brown, tan or black patches, spots, tips or margins; it is permanent and the end point of many nutrient, salt, pest, disease and environmental problems.

- Canonical: https://genetixbay.com/knowledge/glossary/necrosis.html
- Also written: necrotic, necrotic spots, dead tissue, leaf necrosis
- Glossary category: Plant biology · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

Necrosis is dead plant tissue. On leaves it shows as dry brown or tan tips, margins or spots, or as black, water-soaked patches when disease is involved. It usually follows [chlorosis](https://genetixbay.com/knowledge/glossary/chlorosis.md): the tissue first yellows, then dies (Marschner 2012).

## In practice

The position and shape of the necrosis help the diagnosis: brown tips on newest mature leaves suggest [salt build-up](https://genetixbay.com/knowledge/glossary/salt-build-up.md); tan margins on old leaves suggest potassium; spots with yellow halos on new or middle leaves suggest calcium; spots with dark margins and tiny black specks suggest [septoria](https://genetixbay.com/knowledge/glossary/septoria-leaf-spot.md). Necrotic tissue never recovers, so judge any fix by the new growth that follows it (Cockson et al. 2019).

## Don't confuse with

- **Chlorosis**: yellowing that can still recover.
- **Senescence**: programmed ageing of old leaves.
- **Light bleaching**: white rather than brown tissue at the canopy top.

## Related terms

[Chlorosis](https://genetixbay.com/knowledge/glossary/chlorosis.md), [Interveinal chlorosis](https://genetixbay.com/knowledge/glossary/interveinal-chlorosis.md), [Nutrient burn](https://genetixbay.com/knowledge/glossary/nutrient-burn.md), [Leaf spot](https://genetixbay.com/knowledge/glossary/leaf-spot.md)

## Read more

- [Brown or burnt leaf tips on cannabis: a differential](https://genetixbay.com/knowledge/diagnosis/brown-burnt-tips.md)
- [Rust-coloured spots on cannabis leaves: a differential](https://genetixbay.com/knowledge/diagnosis/rust-spots.md)
- [Cannabis lookalike problems: how to tell them apart](https://genetixbay.com/knowledge/diagnosis/lookalikes.md)

## Sources

1. Marschner P (ed.). 2012. Marschner's Mineral Nutrition of Higher Plants, 3rd ed. Academic Press. https://doi.org/10.1016/C2009-0-63043-9
2. Cockson P, et al., 2019. Characterization of Nutrient Disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432