Round 3... outdoor this time. I have some discolouration or powdery mildew on some leaves

Hi guys! Round 3.

White widow - 2gal fabric pot, started indoor and moved outside. Been alive for about 4 weeks.
Blueberry - 3gal pot, started indoor and moved outside. Alive 3 weeks.

Both autoflowers.

As per below image, my white widow seems to have powdery mildew or something on some leaves… not sure if thats what it is. I have been spraying with neem, any suggestions?


Your picture is too far away. But from here, I don’t see anything to worry about

I will take another tomorrow. Thanks mate.

Hopefully that helps mate!! Thanks.

Powdery Mildew is spottier than that. Does it wipe off?

And are you checking your PH?

I need to check pH. I will do that tonight, its likely 7, but i will double check. Most of my soils have been 7. I have it in a super soil mix of my own as well and ive added myxorrizhae last week too.

It doesnt wipe off, i tried to use a wet paper towel and wipe and it didnt work.


For soil, 6.5 would be preferred. Here’s the symptom checker article I was thinking of:

And then here’s a chart that floats around:

I never have a lot of luck with those charts. It doesn’t look like pests to me so, were it my plant, I’d be sure the PH was in range and apply a fertilizer if you haven’t already. A decent fertilizer like the Fox farm line will have all the micronutrients it should need.

Ive got it in a super soil mix which should be plentiful in nutrients, maybe ill double check it.

Thats some handy images you got there mate thanks, will save those. Ill check pH, maybe something isnt right there. Would make sense. Thanks mate.

Maybe this guy @garrigan62 will happen by, scroll up and look at the pics. He’s pretty good at diagnosing these things.

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Haha thatd be helpful. I think i gotta check pH more than anything at this stage. Only thing i have though is that soil tester solution you mix in thay coloured liquid. Hopefully is able to tell me what i need.

Also, i noticed that the leaves which the discolouration are also really big… maybe a sign of excess nutrients of some sort…


You have a bad case of " White Powdery Mildew "


What causes White Powdery Mildew?

High Humidity

WPM needs moisture to thrive, but that doesn’t necessarily mean it needs water.
Having a grow area with
high humidity is all WPM needs to grow. This seems to be a bit problematic since
young cannabis plants
grow best in relatively humid environments (40% -60% RH). Luckily, high humidity
usually only becomes an
issue when it’s combined with the next cause (low/no airflow).

People who live in environments with extremely high humidity (such as Florida
and the UK) can purchase a
dehumidifier to control humidity in the grow area. This is especially important
during the flowering phase
when humidity needs to be much lower (45% rh) to prevent rampant growth of WPM
and bud mold.

Low/No Airflow

White Powdery Mildew has a hard time settling in a grow room where the air is
being moved. High humidity
will give WPM the conditions it needs to survive, but poor airflow is what gives
it the ability to settle
down in the first place. In fact, a small (preferably oscillating) fan moving air
in a grow area will prevent
the vast majority of White Powdery Mildew woes.

Poor Ventilation

If you have WPM spores in your grow area and the air in grow area is never
exchanged for fresh air, the
spores get multiple chances to land on your plants and reproduce. This happens
most often in conditions
where cannabis is being grown in a closed, unventilated space - such as a closet -
and precautions aren’t
taken to exchange old stale air for new fresh air.

Leaf-Leaf Contact

Leaf to leaf contact = moisture = White Powdery Mildew!Leaves that are touching
each other will form
moisture between them, and thus they become more likely to contract WPM. Untrained
bushy/leafy plants
with lots of new vegetative growth are especially prone since plants will often have
leaves mashed up
against each other as they try to reach the light.

Advanced growers can defoliate some of the fan leaves that are completely shaded
from the grow light
to make fewer choice landing spots for White Powdery Mildew. Also, defoliation
frees up energy for the
plant to use when done correctly and increases yields! See our article on
defoliation for more info.

White powdery mold on the stem of an outdoor plant - White powdery mold can
grow nearly anywhere on the
plant that’s exposed to air.

How to Eliminate White Powdery Mildew

As I mentioned earlier, I recently had a battle with White Powdery Mildew. Rather,
it might have been a
battle if I noticed it later or waited to fix the problem. That’s the one good
hing about WPM: in most
cases when WPM is caught early, you can remove all traces of the mildew without
harming your plants.

There are quite a few products and homemade concoctions people use to treat WPM.
Among the effective treatments are:

Milk (1:9 ratio of milk to water)

Baking soda (2 tablespoons per gallon of water)

Neem Oil (4 teaspoons per gallon of water)

Hydrogen Peroxide (1 teaspoon per gallon of 35% H202)

SM-90 (1:5 ratio of SM-90 to water)

Rather than go into these methods, I’m going to give you the simple strategy I use
that gets rid of White
Powdery Mildew on the first try, every time! Here’s my trusted 3-Step White Powdery
Mold cure:

1.White Powdery Mold: Ruiner of beautiful plants.Remove White Powdery Mildew from leaves -
Get some water
(tap water works fine) and some paper towels. Wet the paper towels and use them to g
ently wipe the mildew
off the affected leaves whilst being careful not to jostle any leaves with spores on
them. Using a wet cloth
will ensure that more spores stick to the cloth instead of becoming airborne. Note:
While it isn’t necessary
to use paper towels, their disposability helps to curb the spread of spores from one
leaf to another.

2.Ensure plants have proper airflow and ventilation - Even if you have absolutely no
airflow or ventilation
in your grow room, having even two fans will drastically reduce your chances of
encountering WPM while also
benefitting your plants overall health. One fan should be oscillating if possible
and should gently blow air
over your plants. All the plants need is enough air to gently rustle their leaves.
The second fan should be
in your grow room pointing outward, pulling heat away from your plants (only needed
if you have no ventilation).
Having a fan pointing out of your grow room will force old air out of the room, and
in turn, pull new air into
the room. At this point, you’ll have new air coming in, being used and circulated,
then kicked out. Keep in mind
that two fans is a minimum.

3.Treat plant with SM90 to kill spores prevent future growth - Mix 1 part SM90 to 5
parts water(I’ve found 7 parts
water to be equally effective) in a clean sprayer/mister. Wait until just before your
lights for off for the day
and mist your (newly cleaned) plants. Get all the leaves! This diluted SM90 mixed will
kill any spores it touches,
and anywhere it lands becomes uninhabitable for future spores. Plus, it’s safe to use -
even during flowering - and
it smells awesome.

There you have it. If you end up running into White Powdery Mildew, give this advice a
shot and you won’t have to
deal with it past that first day. If you do end up using these steps, feel free to
let us know if it helped you or
not, or how you did it differently. When growers know just a little bit about this
disease, it doesn’t have a chance!

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Hey mate i found this online and have tried the paper towels and neem so far to no avail. They are outside so they should have airfly and its not very humid here where i live its about 50-60%.

Might try the milk method or something else i vuess! Thanks.


I hope it works for you my friend. Please let me know how it go’s for you ok


Thank you i will.