Greenhouse trials evaluating Cannabis sativa hemp cultivars as hosts for multiple Meloidogyne root-knot nematode species, including galling, reproduction, cultivar response, and growth effects under infested conditions.
Diseases
Root-Knot Nematodes
Root-knot nematodes (Meloidogyne spp.) are plant-parasitic roundworms that can reproduce on Cannabis sativa. Hemp studies show that susceptibility and visible galling can vary, so root symptoms should be paired with soil or root testing before the cause is assigned.
What to look for
- Root galls, swellings, or distorted fine-root development
- Patchy stunting or reduced vigor that may be more severe in heavily infested soil
- Reduced root function without a distinctive foliar symptom pattern
- Field or media history that includes known root-knot hosts or prior nematode problems
Important look-alikes
- Crown gall or other abnormal root swellings
- Root aphids and other root-zone pests
- Pythium- or Fusarium-associated root decline
- Compaction, low oxygen, salinity, or irrigation stress
How to confirm
- Inspect washed roots for galling and abnormal fine-root structure
- Submit representative roots and substrate or soil for nematode extraction and identification
- Compare symptomatic and apparently healthy zones instead of sampling one plant
- Interpret hemp research cautiously because cultivar and nematode species can change symptom severity
Management principles
- Base management on confirmed plant-parasitic nematode presence and species context
- Avoid moving infested soil, media, roots, or contaminated equipment into clean zones
- Use crop-system-appropriate sanitation, exclusion, and root-zone management rather than relying on foliar symptoms
- Track affected zones over time to determine whether pressure is expanding
Prevention
- Know the nematode history of outdoor sites and reused media systems
- Start with clean propagation material and uncontaminated media
- Clean soil- or media-contact equipment before moving between zones
- Use representative diagnostic sampling when unexplained patchy decline persists
Visual study guide
- Healthy root versus root-knot galling plate
- Root-knot nematode lifecycle diagram
- Root gall differential comparison
- Representative soil and root sampling guide
Evidence & further reading