Hydrolife Magazine August/September 2016 (USA Edition)

grow
Is It Time to Say Goodbye
to Your Fan Leaves?
by Cory Hughes | Dense canopies can cause a
variety of problems in your growroom. By taking
the time to get hands-on with your plants and
removing excess fan leaves, you can save yourself
a ton of heat and moisture related problems.
By far, one of the most overlooked practices in maintaining
a pest- and mildew-free environment for your cannabis
plants is the manual removal of fan leaves. Removing
excess fan leaves and creating airflow to the central,
denser areas of your canopy is essential in maximizing
yields. Balancing your temperature and humidity is a good
start, but it’s not enough to produce the end results you are
looking for. You need proper ventilation and air circulation
in order to optimize your plants’ ability to take in the
rich atmosphere around them. Sometimes, however, due to
the density of your canopy, airflow can become restricted
despite having a good HVAC and ventilation system.
If your plants are in late stage and looking great, but you
find pockets of powdery mildew when you dig into the
dense canopy, manual removal could have probably saved
you some heartache. Powdery mildew is a fungal disease
that at a glance looks like baking flour dusted on your
plants. It thrives in warm, moist conditions. 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.
When the density of your canopy reaches a certain point,
temperatures and humidity can rise. The fresh, cool air
from your HVAC just can’t efficiently reach the central
dense areas. 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.
Another problem that may arise is an infestation of spider
mites. Spider mites, much like powdery mildew, love warm,
humid conditions. These are pests that are hard to completely
remove. As a friend of mine once put it, it’s about integrated
pest management, not integrated pest eradication.
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.
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. 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. Those tiny crystalline beauties
can go on to make extractions, so you might want to leave
them. At first you should only be concerned about removing
the large fan leaves that are obstructing airflow to the core
of your canopy, and then approach the removal process from
different angles. 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.
If you have to manually remove powdery mildew-covered
leaves, it won’t entirely remove the problem, but it’s a start.
You are really only removing the leaves to prevent the
mildew from spreading further. 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.
Growing cannabis is one heck of a balancing act. The
manual removal of fan leaves to control pockets of humidity
and prevent fungal infections is just one part of a larger
pest management program. Keeping away the critters and
the mildews may seem challenging, but putting to use best
practices of an integrated pest management system works.
Manual fan removal is one of the easiest and best ways to
boost the health of your plants.
Cory Hughes is a former police officer turned full-time
commercial grower in Denver, Colorado.
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grow. heal. live. enjoy.
myhydrolife.com