I also think it is bud rot aka botyrtis. I found this info:
Budrot (Botrytis) is a very common worldwide fungus that attacks both indoor and outdoor crops under certain conditions. “Budrot” is also known as “brown rot”, “grey mold” and other names. Airborne Botrytis spores can be found everywhere, all times of the year, and will attack many different species of plants. Botrytis will attack flowers, and eventually leaves and stems.
Growers running sea of green, perpetual harvest, remote grows, outdoor, or multiple strains (each with different flowering periods) should keep an eye out for Botrytis near harvest time.
Outdoor growers need to be hypersensitive to weather conditions near harvest time. Rain, morning dew, frost and cool fall nights may increase the risk of budrot and powdery mildew.
Fully developed marijuana buds provide ideal conditions for spore germination: warm and moist plant tissues. Botrytis will initially attack
the largest and densest buds in the garden, because they provide the ideal conditions for germination. Weak plants will also be attacked rapidly.
Budrot will infect and turn colas to mush in a matter of days and may destroy a crop in a week if left unchecked. Botrytis loves warm, and humid (50% or over humidity) conditions. Lowering humidity will slow and stop spore germination. Good ventilation and decent air circulation help prevent infection.
A grow room may smell noticeably moldy if Botrytis has attacked one or more colas. Once a cola has been infected, Botrytis will spread incredibly fast. Entire colas will turn to brown mush and spores will be produced, attacking other nearby colas.
Ventilation may spread viable spores throughout the room.
Measures to prevent budrot in the final stages of flowering:
* Early veg and flower pruning of undergrowth to promote air circulation
* Hepa filter room and intake air sources.
* Introduce low levels of ozone into room air. Ozone is effective against pollen, podwery mildew and other airborne spores.
* Lowering room humidity (warming nighttime air and venting frequently or using a dehumidifier)
* Decreasing watering cycles and amounts to reduce room humidity
* Large, dense colas should be periodically inspected. Brown tissues deep within the bud will smell moldy and may become liquid.
* Removing fan leaves during the last few days before harvest to promote air circulation
* Serenade
What if budrot is found?
Once budrot has been detected, the grower should isolate infected buds by removing them from the growroom immediately and harvesting the infected colas, followed by a rapid dry of the harvested colas. Take immediate steps to reduce room humidity. Afterwards, the entire crop should be carefully inspected for infection and damage.
The grower may want to harvest early if more than one rotting cola has been found. Spores may have spread and are germinating deep within other colas.
Can I salvage budrot-infected colas?
Yes. Remove the infected colas from the main room, Trim out the infection (Trim more than you can see – Botrytis often infects adjacent tissues) and quick-dry them. Re-inspect buds – they should not smell moldy.
Smoking infected buds is not recommended.
