# Mold

> The everyday word for visible fungal growth; on cannabis it covers several distinct diseases, mainly bud rot (Botrytis cinerea) and powdery mildew (Golovinomyces ambrosiae).

- Canonical: https://genetixbay.com/knowledge/glossary/mold.html
- Also written: mould, moldy buds, mouldy, mildew, mold and mildew, fungal growth
- Glossary category: Pests and diseases · 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"

Mold (mould in British and Canadian English) is a loose word for fungi that grow as visible threads and spores. Growers use "mold" and "mildew" for very different problems, so the first step is naming the organism. On living cannabis the main ones are [bud rot](https://genetixbay.com/knowledge/glossary/botrytis.md) (*Botrytis cinerea*), [powdery mildew](https://genetixbay.com/knowledge/glossary/powdery-mildew.md) (*Golovinomyces ambrosiae*), [white mould](https://genetixbay.com/knowledge/glossary/white-mould.md) (*Sclerotinia sclerotiorum*) and, outdoors, [downy mildew](https://genetixbay.com/knowledge/glossary/downy-mildew.md). After harvest, *Penicillium* and *Aspergillus* species can grow on buds that are dried or stored too wet.

## In practice

Each has a different cause and fix: bud rot follows cool, humid, stagnant conditions inside dense [colas](https://genetixbay.com/knowledge/glossary/cola.md); powdery mildew spreads in moderate humidity without leaf wetness; storage moulds follow high [water activity](https://genetixbay.com/knowledge/glossary/water-activity.md) in the jar. Some *Aspergillus* species are a health concern for people with weakened immunity, which is one reason many markets test for them. Mouldy flower should be discarded, not trimmed and smoked. [Prevention](https://genetixbay.com/knowledge/glossary/cultural-control.md) beats every cure: humidity control, airflow and a proper dry.

## Don't confuse with

- **Trichomes**: glittering [resin heads](https://genetixbay.com/knowledge/glossary/trichome.md), not fuzzy growth.
- **Total yeast and mold (TYM)**: a lab count, not a single organism.

## Related terms

[Botrytis](https://genetixbay.com/knowledge/glossary/botrytis.md), [Powdery mildew](https://genetixbay.com/knowledge/glossary/powdery-mildew.md), [White mould](https://genetixbay.com/knowledge/glossary/white-mould.md), [Downy mildew](https://genetixbay.com/knowledge/glossary/downy-mildew.md), [Sanitation](https://genetixbay.com/knowledge/glossary/sanitation.md)

## Read more

- [Botrytis (bud rot / grey mould) in cannabis](https://genetixbay.com/knowledge/diseases/botrytis-bud-rot.md)
- [Powdery mildew in cannabis](https://genetixbay.com/knowledge/diseases/powdery-mildew.md)

## Sources

1. Punja ZK, Collyer D, Scott C, et al., 2019. Pathogens and molds affecting production and quality of Cannabis sativa L. Frontiers in Plant Science 10:1120. https://www.frontiersin.org/articles/10.3389/fpls.2019.01120/full
2. PNW Plant Disease Management Handbook. Hemp (Cannabis sativa) - Gray Mold (Botrytis Bud Blight and Stem Canker). https://pnwhandbooks.org/plantdisease/host-disease/hemp-cannabis-sativa-gray-mold-botrytis-bud-blight-stem-canker