TLDR: Where I am, I just assume everything has mold and act accordingly.
The long version:
More than likely every bud has some degree of mold infection, once it's that visible there's little you can do. There are endless opinions on the matter, most say, "smoke no mold," I fall into this category *mostly.
Dispensaries are running UV sterilization on moldy bud, washing the hell out of it, distilling it and then packing it into pens if the batch passes the mold tests after the processing. So if you get dispensary pens, you've probably smoked some* parts per million of mold. Since the throw away threshold is a measurable percentage above zero, it's low but it's not zero. It kind of depends on the state, the dispensary, and the level of regulation that's actually going into the industry in your area. The one I worked at has a UV lab or they'd be throwing away 16 rooms of 5000 plants each, 95% of their annual crops. Greenhouses in a swamp, we had very few months with no mold.
That being said, most of us don't have a UV sterilization chamber or multi-million dollar distillation and filtration hardware. So your options are few, if it were my crop I'd probably toss the whole thing now and wash the room. I've been there, it sucks, that's what I've done.
I've been taking allergy meds for mold over 20 years because i live in a state that's comprised of roughly 60% mold by volume 30% swamp gas and 10% people. We recently visited Nevada and I swear I haven't smelled air that free of mold in over 20 years. I thought the air smelled clean and there was a smog advisory going on. I didn't notice the pollution due to the lack of mold.
Wash, I mean scrub everything that you can without destroying it, with soap and water. Dry immediately, don't let it air dry. Sanitize the area, your option on choices. I've used bleach or 15% food grade hydrogen peroxide in my private grow depending on what I could get my hands on. At the dispensary we used 35% Hydrogen Peroxide with 5% Peroxyacetic Acid. I still haven't found a hookup for that in low quantity consumer sizes yet, or available without some kind of license. So the grooviest bleach or hydrogen peroxide you can find. Anything disposable, dispose of it. Anything electronic unplug and clean as best you can with Iso Alcohol.
How hardcore you go is up to you. The first time I got mold I gutted my whole grow and repainted all surfaces with Killz after cleaning and sanitizing to combat molds. I would say the only thing too extreme would be where you poison yourself or burn the place down.
Get your humidity down if you can, on a good day with 2 dehumidifiers running 24/7 I might pull 45% RH for a few hours, and I've spent a small fortune and a decade slowly sealing my house.
Once your back and running, genetics, genetics, genetics. We had genetics at the greenhouses that would not get mold, 115°F 80-90% RH for weeks, two other strains in the room covered in mold, these few genetics still wouldn't get it...but they had other pest problems as bad as the mold. I'd tell you what the line was but their breeder / actual genetic line is a mystery to me, by the time I was working with them as an IPM tech they had been re-marketed by the company and may or may not have had a name that had anything at all to do with its actual genetic line.
It's a dance, you need resistant genetics if you're in a hot wet place, I've had very bad luck with US genetics overall, Euro-genetics has only failed me twice, but the US is 3/3 in mold producers. In the old days of using Attitude seed bank I always select high mold resistance as my first option on the seed selector.
Also remember no matter where you get your humidity levels the plant is easily 80% water. If you run wet soil all the time, you may not get leaf droop or other over watering signs but you may be packing too much water into the buds providing a perfect place for a spare mold spore to make a home. I personally haven't watered to runoff in almost 6 years, I water to moist in soil, for me in 5 gal RainScience pots, at peak flower they get 3 quarts every other day, runoff is about a gallon and a half. If your hydro, maybe try reducing your water cycle a little bit at a time. In soil cut back or reduce by one watering a week.
#1 Clean all the things, almost no extreme is too extremely clean.
#2 Air flow, keep it moving, keep it as clean as you can. Filter in and out if you can.
#3 Temp, humidity, and watering controls. It's a dance and there is no golden number, I keep my grow at 76° or as close as I can, in truth it's got a range of about 15° between max and min that I'm trying to reduce. It can pop as high as 80° and as low as 65° at the canopy when the AC is on full blast. My fantasy is a room separated from the rest the AC with it's own system and complete filtration so I don't have to set the temps and humidity choosing between a happy plant or a happy wife.
It's a bitch, the lights produce heat, the fans produce heat, the dehumidifiers produce heat. I've already killed 1 AC system and #2 is on its last legs after 10 years.
Since you can walk outside and smell the mold in the air where I live, I've seen the spore reports from the control outside, it's not pretty; I decided modern problems require modern solutions and now attack it everywhere I can, with energy weapons.
https://toolklean.com/products/uv-sanitizer-lamp?variant=31913862332490¤cy=USD&srsltid=AfmBOooxeKmuMK2AKBHNRW960mqNz52Raf0EDca5K7Rqe9LPD02unpE65zA
I sprung for one of these and have been nuking every room of my house at least once a month while it's empty of people things. I also have a air conditioner unit in my air handler that UV sanitizes the air conditioner coils. I also irradiate the grow area between every harvest. The veg plants are easy enough to take out of the room while I blast it with an hour of UV. I did irradiate the veg plants, once, from the other side of the room for 15 minutes. They had some minor leaf damage the next day but recovered. I haven't had the courage to try UV on flowers yet, but I'm considering some small UV-b-c diodes to turn on for about 15 minutes a day.
Since implementation those two options I've not had any more bud rot problems <knocks on wood.> but I also changed genetics, cutback watering some, did all the things.
I just finished harvest and wet trim today, inspected each branch with my loupe, didn't see anything. Took a random sampling of buds and looked with the USB microscope and couldn't find anything. Still gave them a 3 bucket bud washing, just in case. Bud washing has its own set of controversies associated with it, but so far I've not had any problems with it and generally feel my bud smokes cleaner than it used to.
I just assume even if I can't see it there is some PPM of mold, just as a fact that I can smell it when I walk outside anywhere here. So I bud-wash, after trim and before drying, and inspect at every step from first flower to cure with a loupe and scope.
