# Action threshold

> The pest or disease level, set in advance, at which a grower takes a specific control action because waiting longer would cost more than acting.

- Canonical: https://genetixbay.com/knowledge/glossary/action-threshold.html
- Also written: economic threshold, treatment threshold, intervention threshold, action level, economic injury level
- 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"

An action threshold is the level of pest or disease, measured by scouting, at which a defined control step is triggered. In field crops it is tied to the economic injury level, the point where damage costs more than control. For high-value cannabis, thresholds are set low because the tolerance for damage or contamination in flowers is close to zero.

## In practice

Thresholds turn vague worry into a rule. Examples a grower might write down: more than 10 [thrips](https://genetixbay.com/knowledge/glossary/thrips.md) per yellow card per week in veg triggers an extra predator release; any confirmed [broad mite](https://genetixbay.com/knowledge/glossary/broad-mite.md) or [russet mite](https://genetixbay.com/knowledge/glossary/hemp-russet-mite.md) on a clone triggers destruction of that batch; any [powdery mildew](https://genetixbay.com/knowledge/glossary/powdery-mildew.md) colony in late veg triggers removal of affected leaves and an environment check. The numbers are grower-set, not universal; record counts weekly and adjust thresholds as you learn what your room tolerates. Stage matters: the same count that is tolerable in early veg can be unacceptable two weeks into flower, when options run out.

## Don't confuse with

- **Economic injury level**: the damage break-even point; the action threshold sits below it to leave time to act.
- **Zero tolerance**: a threshold of one, used for pests such as russet mites and for pathogens such as [HLVd](https://genetixbay.com/knowledge/glossary/hop-latent-viroid.md).
- **Spray schedule**: action by calendar, not by count.

## Related terms

[IPM](https://genetixbay.com/knowledge/glossary/ipm.md), [Scouting](https://genetixbay.com/knowledge/glossary/scouting.md), [Sticky trap](https://genetixbay.com/knowledge/glossary/sticky-trap.md), [Preventive release](https://genetixbay.com/knowledge/glossary/preventive-release.md)

## Read more

- [Sanitation and disease prevention for cannabis grows](https://genetixbay.com/knowledge/diseases/sanitation-and-prevention.md)

## Sources

1. Michigan State University Extension. Managing greenhouse insects. https://www.canr.msu.edu/news/managing_greenhouse_insects