Like all plants, cannabis plants are susceptible to diseases and pests. Early detection and the right countermeasures are crucial to securing yields and ensuring plant health. In this blog post, we look at the most common diseases in cannabis plants and how to combat them effectively.
1. Powdery mildew
Symptoms:
• White, powdery coating on leaves and stems.
• Leaves may turn yellow and die.
Cause:
Powdery mildew is caused by fungal spores that spread quickly in a damp, poorly ventilated environment.
Fighting:
• Prevention : Good air circulation, optimal humidity (40–60%).
• Treatment : Remove and dispose of infected leaves. Baking soda solutions or special fungicides can help to combat the fungus.
2. Root rot
Symptoms:
• Yellow, limp leaves.
• Bad smell in the root area.
• Roots are brown and mushy.
Cause:
Overwatering and poor drainage promote the growth of fungi such as Pythium , which attack the roots.
Fighting:
• Prevention : Use well-drained substrate and avoid waterlogging.
• Treatment : Repot affected plants in fresh soil, clean roots thoroughly with water. Mycorrhizal fungi can promote root growth.
3. Gray mold (Botrytis)
Symptoms:
• Gray, furry mold on flowers and stems.
• Flowers become mushy and fall apart.
Cause:
High humidity and lack of ventilation promote the spread of this fungus.
Fighting:
• Prevention : Keep humidity below 50% during flowering, trim leaves regularly to improve air circulation.
• Treatment : Remove and dispose of affected parts immediately. Fungicides can help control the infestation.
4. Spider mites
Symptoms:
• Small yellow dots on the leaves.
• Thin, fine spider webs on the underside of the leaves.
Cause:
Spider mites reproduce particularly quickly in dry, warm environments.
Fighting:
• Prevention : Increase humidity and check plants regularly for pests.
• Treatment : Neem oil, potash soap or special insecticides can kill spider mites. Natural predators such as ladybugs are also effective.
5. Nutrient deficiency
Symptoms:
• Yellow, discolored or deformed leaves.
• Slow growth.
Cause:
An imbalance in the pH value or incorrect fertilization means that the plant cannot absorb important nutrients.
Fighting:
• Prevention : Regularly measure pH (ideal range: 6.0–7.0 in soil, 5.5–6.5 in hydro systems).
• Treatment : If a certain nutrient is missing, it can be added specifically via fertilizers.
6. Whiteflies
Symptoms:
• Small, white flies that rise when the plant is touched.
• Yellow leaves, sticky substances on the plants.
Cause:
The flies lay their eggs on the plant and the larvae suck out the plant sap.
Fighting:
• Prevention : Put up yellow signs to attract the flies.
• Treatment : Use neem oil or insecticidal soaps.
General tips for preventing diseases
1st Hygiene : Clean tools and growing areas are essential.
2nd Create optimal conditions : Temperature, humidity and light should always be in the right range.
3. Regular checks : Check plants weekly for pests and diseases.
Conclusion
Diseases and pests in cannabis plants can significantly reduce yields. However, with a preventative approach, regular checks and the right treatment, most problems can be successfully managed. Healthy plants are the basis for a good harvest - so always pay attention to their needs!