Most Common Pests In Cannabis: Powdery Mildew

Powdery mildew comes from fungus and fills your leaves with white fuzz, inhibiting photosynthesis.
Author Enzo Schillaci
25 June 2020
5 min read
 Most Common Pests In Cannabis: Powdery Mildew


Powdery Mildew comes from different types of fungus, it slowly starts developing on your cannabis leaves and if left without care for too long can completely take over your plant. If you're tired from having to deal with this, this article is just for you!

1. What is powdery mildew?

Powdery mildew (or White Powdery Mildew) is a type of fungus that coats your plant's leaves, can inhibit photosynthesis and rot buds. Even though it can seriously affect your plants, you can easily get rid of it without too much hassle with homemade or store-bought products, like Neem oil.

This type of fungus can affects a wide variety of plants, including cannabis.

It develops what looks like white fuzz on top of your cannabis plant leaves and can reproduce both sexually and asexually, spreading spores all throughout your growing space, spreading to other plants around super fast.

2. What does powdery mildew look like?

Powdery mildew looks like flour or fuzz, it’s a white powder that forms circular patches all over the leaves. 


Powdery mildew looks like a white fuzz that slowly starts to take over your plants.

When the mildew starts to take over your plants you’ll easily see a layer of white spores on top of the leaves.

They can easily be spotted because of the contrast with the bright green cannabis leaves.

3. Where is powdery mildew found?

This fungus is mostly found on top of the cannabis leaves in the early stages and can be found all over after it spreads, also affecting the buds.

If you see your buds with a fine white layer of white powder, it won't take long until they start to brown and smell bad.


When mildew reaches the buds they start to rot and at that point, you should discard them.

Note: Have in mind that when powdery mildew reaches the buds you should discard them, even if they are not completely rotten because they can be toxic for us.

4. What does powdery mildew do?

Powdery mildew slowly covers the surface of cannabis leaves, this will ultimately inhibit photosynthesis.

This will cause the leaves to yellow, turn brown, and ultimately die due to the lack of energy.

5. Powdery mildew symptoms

In the first couple of days, you won’t be able to see anything but the spores are slowly infecting your plant.

After a couple of days, you’ll start to see white spots on the leaves, these spots start to spread to the rest of the leaves through spores and they end up looking completely white and fuzzy.


Mildew can easily spread to other plants around through spores.

In more serious cases, the buds will also be infected and they will start to rot, having white fuzz all over and ultimately starting to turn brown and smelling bad.

6. How to prevent it?

It is really easy to get powdery mildew so to prevent it you should have a good growing environment, always checking (and adjusting if necessary) humidity levels and airflow.

Because this is a fungus, it thrives in humid places where there’s no airflow to evaporate the water.

Even though you can have a relatively high humidity level (in the seedling stage, for example), you have to provide a good airflow because the powdery mildew spores cannot settle down where the air is being moved.

7. How to deal with it?

There are several ways of eliminating powdery mildew and if you spot it early, it should be very simple to do so.

First of all, it is recommended you remove the infected plants from your growing room, although if it’s widely spread it’s likely all your plants already have it.

You can use Neem oil but this can be bad if used on the flowering stage, for more safe options you can spray milk or baking soda mixed with water in the following ratio:


You should start with less harmful ways to deal with mildew before moving to other ways.

  • Mix 900ml of water with 100ml of milk
  • Mix 1 tablespoons of baking soda with 2L of water

You should spray once or twice on the affected leaves without overdoing it because it can have a negative effect on your plants.

8. In Conclusion

Powdery mildew is a fairly simple pest to take care of and by having a fan moving the air in your growing space you can easily prevent it.

If you have powdery mildew in your growing room, make sure you try the less harmful ways of dealing with it before trying anything else.

Top 10 Strongest strains

Gelato Auto
Gelato Auto
Our most powerful strain yet. 26% THC lab reports, and distinct Ice cream flavours. 
Buy seeds from 13,00 €
Gorilla Glue Auto
Gorilla Glue Auto
A platinum strain, with more than a million sold all over the world!
Buy seeds from 13,00 €
OG Kush Auto
OG Kush Auto
Next level potency and delicious Kush flavor
Buy seeds from 9,00 €
Show more strains (5)