Bud rot is the worst nightmare for marijuana growers. It's hard to prevent or identify and it will ruin your whole cannabis crop. Bud rot develops on the inside of the buds and spreads very quick. Even when your marijuana is drying, this mold will stay active so make sure you're well prepared this nasty fungus.
1. Prevention is better than cure
Bud rot, also known as botrytis cinerea or grey mold, thrives best when air is very humid and temperatures are low. It develops in the last phase of the flowering period, when air humidity should be between 30% and 40%. The problem is that humidity will increase as you water your marijuana plants. This is why you have to make sure not to give plants too much water and prevent excess spilling. If you water your plants from underneath, make sure you dose the amount so that it takes no longer than one hour for the plants to absorb all of the water. Also, water your plants when the lights have just turned on. Temperatures are then higher and water will damp or be absorbed quicker than when lights are out and your marijuana plants are 'sleeping'. In addition, make sure the space is very well ventilated and excess air is extracted. Fans must blow air between the buds and lamps, preferably an oscillating fan.
When growing marijuana outdoors, place your plants in sunlight and in an area where wind creates enough ventilation. Morning dew can then damp quickly evaporate or you can help get rid of dew by gently shaking it off. The best case would be to place your marijuana plants indoors at night so that cold air and damp won't harm them too much. By placing plants slightly higher than the ground for better ground temperatures, you help your plant's resilience against diseases. You can also treat your marijuana plant with Teldor from Bayer. But only use this on the stem during flowering phase so the wax coating does not rinse off easily.
2. Recognizing marijuana bud rot
Keep an extra close eye on your marijuana plants during the last weeks of the flowering period. Always look for diseases and abnormalities, but especially for bud rot. You've come too far to see a good cannabis crop go to waste after all the hours you've spent cultivating your plants. You can recognize bud rot by inspecting the small one finger leaves growing from the buds. If these are green, you're in the clear. If these have a yellow or brown color, chances are you have bud rot. These leaves let go easily when removed and do not look healthy. If you see this kind of leaf, remove it immediately and bend open the top carefully and look inside and see if things are looking OK.
Once you've identified bud rot on your plants, you need to act quickly. It might be hard on you, but you have to remove any and all infested buds. Bud rot spreads very quickly and it will ruin your entire crop. Use disinfected scissors to cut out rotting buds. Also be very careful not to touch healthy buds with your infected hands. Check every day for bud rot and cut out infected buds immediately!