Plant injury from insufficient or excessive root-zone moisture, irrigation diagnosis, overwatering, poor drainage, aeration deficit, and the need to distinguish wet-root and dry-root stress.
Symptom differential
Patchy Container-to-Container Decline
When neighboring plants decline unevenly, distribution can reveal irrigation, drainage, emitter, root disease, pest, media, or placement differences that would be hidden by looking only at one symptomatic plant.
Pattern questions
- Do affected plants share an irrigation line, bench position, media batch, or runoff path?
- Are containers drying at different rates?
- Is the pattern clustered, random, edge-biased, or associated with one cultivar or propagation lot?
- Are root symptoms similar across affected plants?
Plausible cause categories
- Emitter or irrigation nonuniformity
- Localized saturation or poor drainage
- Root disease spread through shared water
- Media inconsistency
- Localized pest pressure
- Environmental edge effect
Discriminating checks
- Measure emitter output and container moisture across the pattern
- Inspect roots from affected and unaffected plants
- Map the problem against irrigation zones, airflow, temperature, and runoff
- Review propagation and media lot records
Red flags
- Rapid spread along shared water routes
- Severe root sloughing
- Blocked or failed emitters
- Clusters linked to one propagation lot
Visual study guide
- Bench-level symptom map
- Emitter-output comparison
- Cluster-pattern examples
- Root comparison panel
Evidence & further reading
Sources connected to this lesson
These references support specific biological, diagnostic, environmental, or process concepts used in this lesson. They are not a substitute for crop-specific testing or local regulatory guidance.Cannabis greenhouse disease diagnosis and integrated management, including powdery mildew, Botrytis, root disease, HLVd, sanitation, irrigation, airflow, and post-harvest microbial risk.