Oidium

One day you check on your plants and they’re covered in some sort of white powder. A few days later you notice it covering the entire plant. What’s happening to your cannabis plants?

It’s oidium, a type of fungus that can easily finish off your entire grow; it weakens plants and stops their growth. If it reaches your flowers, you won’t be able to consume them at all.

This is why it’s super important to not let it get that far; let’s have a look at how to avoid oidium all together.

What is Oidium?

Oidium, also known as powdery mildew, is a common pathogen that appears mainly on vines but can also attack cannabis plants and other plants.

Oidium is the name given to various species of fungus from the Erysiphaceae family, known for acting externally on plants.

There are two types of odoium that attack cannabis plants:

Sphaerotheca Malacularis, also common in strawberries.
Leveillula táurica.

The spores reach your plants through the air and are deposited on the leaves. They can also be transported on clothes, flying insects etc.

When it comes to indoor grows, this pathogen isn’t quite as common, although if it does appear you need to act fast; indoor cannabis grows have the ideal conditions for this fungus to spread.

How to Identify Oidium

When the infestation begins, you’ll see small white stains on your leaves, which should start on the lower leaves of the larger, more robust plants.
Oidium spores accumulate and spread, creating many white stains on your plants’ leaves. It’s quite similar to mildew, although it also grows on the underside of the leaves.
When you see white stains on your plants, you should be aware that the spores are most likely all over the other leaves. You should begin treating it as soon as possible; it’s quite a common mistake to think that the stains are from something else, like ash, bad fertilizer etc.

How to Prevent Oidium

Prevention is vital if you don’t want to run into issues with this fungi; by following a few steps you can avoid a lot of issues:

Keep your growing area clean and get rid of old leaves and leftovers from the last grow. Spores can live through the winter and revive during the next season.
Clean out the flowerpots using water and sop, and then bleach, before using again.
Change your clothes before entering your grow room.
In indoor and greenhouse grows, keep humidity levels low. Outdoors, make sure to separate your plants enough so that there’s plenty of airflow. Make sure that the branches aren’t overlapping and don’t place them against a wall.
Do not use too much nitrogen during the growth stage; if you do, your plants will be more sensitive to fungus infestations.
You can use preventive products such as Cannacure, Protect or Leaf Coat, which creates a protective film around your plants’ leaves making it harder for spores to attach.
When it comes to indoor grows, Clean Light grow lights are highly effective. They use ultraviolet lighting which gets rid of fungi and oidium spores. You can use this treatment as a preventive measure every three days, although you should use protective eyewear when doing this as UV light is bad for your eyes.
There are bio preventive products such as Oidioprot, a bio fungicide that contains amino acids and microorganisms; Ekisan is a fungicide with a horsetail and amino acid base that doesn’t harm animals or the environment.
If you had oidium in your grow outdoors or in a greenhouse, you can use chemical preventives such as Lexor25. This product can be used a few days before your plants begin flowering.
Belprón Special Fluid 90 is an arachnicide and fungicide made using sulphur. This product is apt for ecologically-friendly growing and highly effect against oidium. The only downside to sulphur is that at over 30°C it can be toxic for your plants. You shouldn’t use this product when growing outdoors in climates with higher temperatures.