Botrytis (Bud Rot / Grey Mould)

Grey or brown fuzzy mould developing inside dense buds, sometimes appearing first as a single dying sugar leaf or browning calyx. Highly destructive in late flowering - remove and bag affected colas immediately and well outside the room (do not shake) to prevent spore release. Thrives in cool, humid, stagnant air.

What usually causes it

• RH above ~55% in late flower (target 45-55% for the last 3-4 weeks)
• Poor airflow through dense colas
• Tissue damage from pests, physical contact or earlier PM lesions
• Cold night temperatures causing dewpoint condensation inside the bud

Related product categories

• Fungicides & Disease Control
• Climate & Ventilation

Terms worth knowing

• VPD (Vapour Pressure Deficit)

Walk the questions if you are not sure this is the match. The notes above are the same ones the tool ends on.