# Nutrient toxicity

> Nutrient toxicity is damage from an excess of an element in the plant, either directly or by blocking uptake of others; boron, manganese, copper and chloride are common culprits.

- Canonical: https://genetixbay.com/knowledge/glossary/nutrient-toxicity.html
- Also written: toxicity, nutrient excess, element toxicity, overfeeding
- Glossary category: Nutrients · 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"

Nutrient toxicity is injury caused by too much of a particular element in the plant tissue. Some elements are directly toxic at high levels: [boron](https://genetixbay.com/knowledge/glossary/boron.md), [manganese](https://genetixbay.com/knowledge/glossary/manganese.md), copper, [chloride](https://genetixbay.com/knowledge/glossary/chloride-nutrient.md), sodium and ammonium. Others, such as potassium or phosphorus in excess, do harm mainly by suppressing the uptake of other nutrients and inducing a [deficiency](https://genetixbay.com/knowledge/glossary/nutrient-deficiency.md).

## In practice

Toxicity symptoms often look like deficiencies of a different element: excess manganese induces iron [chlorosis](https://genetixbay.com/knowledge/glossary/chlorosis.md), excess phosphorus induces zinc deficiency, excess potassium induces magnesium or [calcium deficiency](https://genetixbay.com/knowledge/glossary/calcium.md). Direct toxicity often appears as burning of older leaf margins (boron, chloride) or brown speckling (manganese at low [pH](https://genetixbay.com/knowledge/glossary/ph.md)). Causes include overdosing micronutrients, water with high boron, sodium or chloride, pH drift that frees metals, and copper or zinc from plumbing.

## Don't confuse with

- **Nutrient burn**: tip burn from high total [EC](https://genetixbay.com/knowledge/glossary/ec.md) rather than a single element.
- **Nutrient deficiency**: too little rather than too much, though toxicity can cause one.
- **Pesticide phytotoxicity**: damage from a spray, not from nutrition.

## Related terms

[Nutrient deficiency](https://genetixbay.com/knowledge/glossary/nutrient-deficiency.md), [Nutrient burn](https://genetixbay.com/knowledge/glossary/nutrient-burn.md), [Nutrient antagonism](https://genetixbay.com/knowledge/glossary/nutrient-antagonism.md), [Boron](https://genetixbay.com/knowledge/glossary/boron.md), [Manganese](https://genetixbay.com/knowledge/glossary/manganese.md)

## Read more

- [Nutrient antagonism and Mulder's chart: what the evidence actually says](https://genetixbay.com/knowledge/nutrients/nutrient-antagonism.md)
- [Brown or burnt leaf tips on cannabis: a differential](https://genetixbay.com/knowledge/diagnosis/brown-burnt-tips.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, Landis H, Smith T, Hicks K, Whipker BE. 2019. Characterization of nutrient disorders of Cannabis sativa. Applied Sciences 9(20):4432. https://doi.org/10.3390/app9204432