What does white powdery mildew look like?

When it comes to cannabis, there are many pests that could ruin your plants. Think about bug’s, viruses and multiple types of fungus. All these pests have their own treatment methods and the trick for a succesfull treatment is recognizing them on time. Most pests are not that harmfull once they are recognized and treated quickly.

How to get rid of White Powdery Mildew?

In this article we are going to talk about White Powdery Mildew which is an fungal pest that is able to destroy your plants if the treatment is not being done on time. Recognizing the first signs of a WPM infestation is very important. Thats why we are going to show you what White Powdery Mildew looks like in multiple stages of it’s growth!

What does White powdery Mildew look like? Different phases explained:

White powdery mildew is a type of fungus that is pretty easy to recognize. However it comes in different phases which means that sometimes it can pop up out of nowhere (at least thats how it feels).This makes it very important to recognize potential signs of a beginning WPM infestation. In this article we will discuss the different phases and tell you what to look for:

White Powdery mildew phase 1:

In the first phase of white powdery mildew it will be quite hard to notice. It al starts with a few spots on different leaves where a thin layer of Powdery milde starts to grow. Because this layer is so thin, it is fairly transparant and only visible when checking your plants up close. Thats why we always tell people to inspect their plants closely on pests and bugs every +- 2 days.

These tiny layers of WPM could be found on multiple places on the leaves of your plants. Eventually they will start to get bigger and thicker making them easier to spot. Here are some examples:

The first visible signs of fungal growth on leaves caused by WPM. This is the point that the micrsoscopic parts expand and turn visible. This is still the first phase of WPM.
Another thing you will notice in the first phase of WPM is that it appears on multiple single spots and not all over the leaf. These spots will eventually grow and take over the leaf in a later Phase. Once you see these spots, its time to take action!
After a while, the spots will turn bigger and start to spread over the leaf. In this case you are slowly rolling into phase 2. However, if there spots are still isolated and on their own like this image)

White powdery mildew phase 2:

If you don’t start a treatment when spotting the signs described in phase 1, it will take only some days/weeks before you will go into phase 2. In phase 2 you will notice that the spots become more white, bigger and even starting to connect each other. This is the start of a thick white layer that will eventually completely cover a leaf (Phase 3).

In the second phase it becomes way more clear that you are dealing with WPM. The small spots that were hard to see have now turned more visible and can be seend by a quick look at your plant. In this phase you are still able to start a treatment and safe your plants, but you have to be quickly! Here are some examples:

The WPM on these Oak leaves is clearly in the second phase. You can still see the spots where the WPM began to grow, but they are all connected and there is a layer forming between these spots. Eventually, this layer will get thicker and take all over the leave.


This plant has WPM all over it. Some leaves are already in Phase 3 but others (like the one in the front) aren’t fully covered yet. You can still see single spots on that one and they are not all connected yet. When you see this, you really need to take action immediatly as it only takes days to get in phase 3 from here.

White powdery mildew phase 3:

You will get in the last phase of WPM if nothing is being done to treat it in the first 2 phases. At this phase it can be hard to rescue your plants as they are now suffering from it. The WPM will block too much sunlight and your plant isn’t able to do photosynthesis. This will eventually result in brown leaves and a dead plant. Never let it come this far as you have had enough chances to treat it by now.

In the 3th and last phase of WPM, the white layer has become very thick and leaves look like they are bright white. There are no single spots visible as it has become 1 big spot of WPM. It looks a bit like the leaves are snowed under or somebody threw white powder all over them. In this case you should remove the affected leaves, change circumstances and hope for the best… Here are some examples:

This oak leave suffered badly from WPM and is almost fully covered by it. The green is hardly visible and there is no sunlight reaching the leave. Next to leave will turn brown and fall off. If this happens with too much leaves on one plant/tree, it could die from it.
This pumpkin leave is also in the 3th phase of WPM. As you can see, the layer has gotten very thick and blocks most of the sunlight. it’s a matter of days that the leave is fully white and no green will be visible any more.
These oak leaves have been in the 3th phase for a while now. All the green on the leave is gone and the thick layer of fungus has spread over all leaves. I’ts a matter of days that the leaves will die and fall of. This will eventually happen if nothing is being done to treat it. If you let it come this far we recommend to start over.

These are the 3 phases of WPM. It’s always very important to recognize in on time (First phase) and start changing the circumstances to treat this fungal pest. Thats why you should check up on your plants daily and watch very close for bugs or other changes.

Did you found White Powdery Mildew on your plants? Find out how to get rid of it!

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