What is “Bud Rot”?
Botrytis cinerea (“botrytis” from Ancient Greek botrys (βότρυς) meaning “grapes” plus itis for disease) is a fungus that affects many plant species. For grape growers, it is commonly known as botrytis bunch rot; in horticulture, it is usually called grey mould or gray mold. To a cannabis grower it is known as “Bud rot”.
How to spot bud rot
Keep an eye on the dense clusters of buds. Look at the small leaves protruding from the buds. If they are green things are ok. If they crinkle, turn yellow, brown or grey and pull away easily from the plant it is a sign the bud is infected. It pulls away easily because the mould has eaten the stem, killing the leaf.
If you find signs of bud rot act immediately or else it could wipe out your crop in a matter of days!
How to stop bud rot
Cut infected buds/colas from the plant and gently move away and destroy. Don’t try and root out tiny sections this will just knock the spores onto other parts of the plant. Clean whatever you used to cut the bud with alcohol. You will have spores on your hands at this point so do not touch any other buds or plants.
How to save your bud from bud rot
Don’t smoke rotten or mouldy buds. Remove and destroy all affected areas.
For the rest, dry as normal in a well ventilated area. Keep a close eye for signs of rot or mould. When it dries the infected bud will turn white or light grey and will be crumbly. Remove and destroy. Once your bud has dried (after at least 7 days) inspect to see signs of mould then cut away any infected area plus a little more (as the spores are invisible to the naked eye). Cure and keep inspecting.
How to prevent bud rot
Towards the end of flowering spend time each day to check for signs of bud rot.
Botrytis thrives in a humid, cold and dark environment. Keep the temperature above 18°C/64°F. 12-16°C (55-60°F) is the danger zone and should be avoided. Make sure you have good ventilation. Use a oscillating fan to circulate the air around the plant. Use a dehumidifier to keep the humidity at 25-50%.
In the growing stage make sure you remove any caterpillars and their poop which can rot and infect the bud. Even better, stop the moths and butterflies getting near your plants in the first place by protecting them with horticultural netting.