Sometimes this “dust” can be ejected from the plant, resulting in a small puff. Gross. The manual removal of fan leaves located deep in your canopy opens tunnels through which fresh air can flow. Why do you need tunnels of air? Opening up your canopy keeps temperatures cool in those deep, dark places.
Here is my strategy for manual fan removal: I like to imagine a point deep in the canopy—one I obviously cannot see. From there it is as simple as removing the fan leaves that are blocking my view.
Stand above your plants and look down. Are there any colas being blocked from the light by excess fan leaves? They should be removed to not only open airflow, but to clear paths of light to areas that may have fallen into the shadows.
Having pockets of warmer, moist air doesn’t always lead to problems with powdery mildew. If the spores aren’t there, then they just aren’t there, but to not find powdery mildew, and to some degree mites, in a home or commercial grow, is rare.
Walk along the side of your tray or growing space and look between each cola. If you can’t see into the heart of the canopy, feel free to start plucking leaves, but be careful not to remove the precious sugar leaves that circle your colas.
At this point, you really should have tackled the problem sooner. Not much consolation, I know, but I’m here to help you prevent these problems in the future. Monitoring your canopy and tackling fan leaf removal early enough will save you a headache later on.
The time you really want to watch for dense pockets of fan leaves is in the mid to late stages. In early stages, density is not a problem. Plus, in early stages you want your plants to grow up and out, using as many fan leaves as possible to suck up energy from your lights.
Now, this might be obvious, but I have to say it anyway: if you are not concerned with maximizing weight through plant count, and are growing for more aficionado purposes, then odds are you are not going to have many of the same problems with your canopy.
The only manual removal that should probably have been done in this instance is your basic bottom pruning. But if weight is your goal, plant count will get you there, and manual removal is your friend.
Best practice for a pest and mildew free environment for your cannabis plants is the manual removal of fan leaves.