Cannabis plants are susceptible to various diseases that can affect yield and harvest quality. Whether fungi, bacteria, or viruses – early detection and treatment is crucial. This guide will explain the most common diseases, how to identify them, and what measures can help.
1. Powdery mildew – The white coating on the leaves
Symptoms:
- White, powdery spots on the upper and lower surfaces of leaves
- Discoloration and deformity of the leaves
- Slowed growth
Causes & Treatment:
Powdery mildew is caused by high humidity and poor ventilation. The following can help combat it:
- Fungicides (e.g. neem oil)
- Improve air circulation
- Remove affected leaves
2. Botrytis (grey mold) – The danger in the flowering phase
Symptoms:
- Gray, moldy spots on flowers and leaves
- Rotten smell
- Brownish discoloration
Causes & Treatment:
Botrytis spreads in humid environments. Prevention and Treatment:
- Check humidity (ideal: 40-50%)
- Cut off damaged plant parts
- Use copper supplements
3. Root rot – The invisible threat
Symptoms:
- Wilting, yellow leaves
- Bad smell from the earth
- Slimy roots
Causes & Treatment:
Overwatering and waterlogging promote root rot. Measures:
- Improve drainage
- Hydroperoxide solution for disinfection
- Use beneficial bacteria (e.g. Bacillus subtilis)
4. Fusarium – The deadly fungus
Symptoms:
- Wilting despite sufficient watering
- Brown-colored stems
- Sudden death of the plant
Causes & Treatment:
Fusarium is difficult to treat, so prevention is important:
- Use sterile substrate
- Growing resistant varieties
- Remove affected plants immediately
5. Tobacco mosaic virus (TMV) – The viral danger
Symptoms:
- Mosaic-like yellow spots on leaves
- Stunted growth
- Lower yield
Causes & Treatment:
TMV is often transmitted by tools or pests. Treatment:
- Hygiene while working (disinfect tools)
- Isolate infected plants
- No cure possible – prevention is crucial
Conclusion: Prevention is the best protection
Most cannabis diseases can be avoided by creating optimal growing conditions:
- Good ventilation & humidity control
- Clean work
- Regular checks
With these tips you can keep your plants healthy and have a successful harvest!