Botrytis (Bud Rot) in Cannabis: Prevention and Treatment

1. Prevention

  • Humidity Control: Maintain proper humidity levels during the flowering stage, aiming for a range of 40-50% to discourage botrytis growth. Use dehumidifiers or fans to improve air circulation.

  • Airflow Management: Ensure good air movement around the plants by spacing them adequately. Prune excess foliage to improve airflow and reduce the chances of moisture buildup.

  • Plant Inspection: Regularly inspect your plants for any signs of stress, damage, or weak spots that can make them more susceptible to botrytis. Remove and dispose of any affected plant material.

  • Plant Hygiene: Keep the growing area clean and free from debris, fallen leaves, and dead plant matter, which can provide a breeding ground for botrytis spores.

  • Quarantine New Plants: Isolate newly acquired plants for a period of time to monitor them for any signs of botrytis or other diseases before introducing them to your garden.

2. Treatment

  • Selective Pruning: Remove and discard any visibly infected buds or plant material to prevent the spread of botrytis. Be sure to sterilize your pruning tools between cuts to avoid cross-contamination.

  • Increased Ventilation: Improve air circulation within the grow space by increasing ventilation, using fans, and adjusting the positioning of oscillating fans to keep the air moving around the plants.

  • Reduced Humidity: If botrytis is already present, lowering the humidity levels below 40% can help inhibit its further spread. However, ensure that the humidity doesn't drop too low to avoid stressing the plants.

  • Organic Sprays: Apply organic fungicides, such as those containing Bacillus subtilis or potassium bicarbonate, to help control botrytis. Follow the instructions provided by the manufacturer.

  • Chemical Treatments: As a last resort, consider using chemical fungicides labeled for botrytis control. Be cautious when using chemicals and always follow the instructions and safety guidelines.

3. Harvesting and Post-Harvest Care

  • Timely Harvesting: Harvest your cannabis plants at the appropriate time to avoid overripe or densely packed buds that are more susceptible to botrytis.

  • Proper Drying and Curing: After harvest, ensure proper drying and curing of the buds. Use a controlled environment with optimal humidity and good airflow to prevent the growth of botrytis during the drying process.

By implementing preventive measures, promptly treating botrytis-infected plants, and practicing proper harvesting and post-harvest care, you can minimize the impact of botrytis on your cannabis crop and protect your hard work.