How to Remove Powdery Mildew on Marijuana Plants

One of the more common problems of marijuana plants is the growth of powdery mildew on the leaves. Also known as white powdery mildew, this problem comes from a mix of different fungi. Outdoor and indoor gardens are both vulnerable to this type of disease.

At first, small bumps would appear on the topsides of the cannabis leaves. Left unchecked, it could grow into white or gray powdery substance which can cover a huge part of the leaves. As a result, photosynthesis can be severely compromised. And in the process, it crushes any hopes for a decent harvest.

But where does it comes from? Spores that freely float on the wind through the ventilation system, pets, or any other living things are the culprits. Basically, they will stay dormant on any surface then emerge once the environment becomes ideal for them.

Therefore, powdery mildew is a tricky problem as we never know when it will strike. It can be lurking anywhere in the garden, waiting for the perfect chance to attack. This is why the best way to deal with it is to prevent its growth in the first place.

In this article, we will discuss the steps to fix this serious condition. This includes the different ways to avoid and get rid of it. Since powdery mildew is not that uncommon, we must regularly monitor for its presence and be ready to deal with it.

How to Get Rid of Powdery Mildew on Cannabis Plants

Powdery mildew plagues cannabis plants in any setup. Oftentimes, it lowers the defenses of the crop which makes them more vulnerable to other pests and diseases. At wort, it can result to very little to no harvest at all. So, learn how to control this problem before it devastates the entire crop.

  • Learn its Nature
Learn its Nature

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One of the hallmarks of powdery mildew is its appearance. Usually, it is white and creates a bold contrast with the marijuana leaves. Since they come from spores, we can’s see them as they spread in the grow room. Hence, it’s extremely tough to prevent them.

  • Ideal Environment

By nature, it is most likely to come to life once the humidity levels go beyond 55% and there is not much air flow in the space. Therefore, it thrives in a damp and overcrowded grow room, especially where the leaves are touching each other. With these conditions, powdery mildew can spread easily and fast which makes it harder to eliminate.

  • Eats up the Young

In general, it likes to wreak havoc on the youngest plants. As such, it consumes the entire plant including the stems, buds, and leaves. If the crop is in the flowering stage when the problem occurs, we will notice a damp smell from the buds.

  • Spreads Rapidly

It’s game over once the fungus invades the buds since it will extremely hard to remove them. As it continues to increase the rate of destruction, the plant will turn yellow, then brown, until it dies.
Hence, it is crucial to prevent the molds from reaching this point. So, always make sure to examine the plants and keep an eye on strange formations. For more information, the next section will discuss the signs and symptoms of infection.

  • Recognize the Signs
Recognize the Signs

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Fortunately, it’s easy to spot powdery mildew infestation. Just check the cannabis leaves for any unusual changes. As such, the most common sign is the fuzzy, flour-like patches that lie in circles on the leaves. Moreover, the leaves will form some spots which will proceed to mottle and wilt. At this point, it will start to infect the surrounding leaves and eat up the whole plant.

Other things to watch out for are the transformation of leaves from vibrant green to pale yellow. As the humidity increases, it’s common for molds to appear and join in the destruction caused by the powdery mildew. So, expect to find other types of mold on the leaves which will cause it to droop.

  • Get Rid of It
Get Rid of It

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Once we observe the first sign of powdery mildew, it’s vital to remove it as quick as we can. Fortunately, there are many easy ways to do these using ingredients that are available at home. So, apply these materials and get ready to say goodbye to the problem.

  • Homemade Remedy

One way to get rid of powdery mildew is by using a popular homemade mix. Simply combine 2 teaspoons of apple cider vinegar and a quart water in a bottle spray. Then, mist the mixture on the leaves to stop fungi from growing. We can also use this as a preventive method.

  • Other Sprays

Oil sprays from neem and sesame seeds are also good options to combat powdery mildew. Even fish oil can do the trick. As a last resort, we can mix 40% milk and 60% water to create the popular milk spray.

Interestingly, proteins in milk form a natural antiseptic when exposed to the sun which then kills the mildew. To keep it at bay, spray every ten days but only when the sun is bright. For indoor growers, artificial lights make a good substitute for the sun if they want to use this method.

  • Tap Water-Paper Towel Method

This method of getting rid of powdery mildew is so simple that we will only need a wet paper towel. With it, gently wipe the infected leaves thoroughly until we can no longer see white patches.

Just make sure to avoid bumping the leaves too much while wiping to stop the invisible pores from spreading. This method is also a good preventive measure to ensure no mildew will develop. Another good option is to wet the paper towel using a quart of water with one-half teaspoon baking soda.

  • Avoid It
Avoid It

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As mentioned, the best way to deal with powdery mildew is to stop it even before it happens. So, here are the methods that guarantee mold-free marijuana plants.

  • Buy Strong Seeds

Perhaps the most obvious way to prevent powdery mildew is to grow seeds with strong genes. As we know, they are more resistant to molds and other diseases and can fend off pests. So, try to buy only high-quality seeds from reputable sources.

  • Give Plenty of Grow Space

As mentioned, powdery mildew thrives in crowded and confined places. So, make sure to provide an extra space for the plant when transplanting them into their mature location.

During the vegetative stage when the plants start to grow more leaves, make sure that they have plenty of space. A good rule of thumb is to position them in such a way that their leaves don’t touch.

  • Optimize Fans

Indoor marijuana gardens usually have fans to help regulate the airflow and prevent molds. Take it a step further by using two fans and positioning the first one to directly blow air through the leaves.

To dispel the “used” air, the second fan should face out from the grow room. As a result, the plants will always have fresh air and powdery mildew will have less chance to grow.

  • Use Plastic Bags for Disposing Infected Leaves

To stop the infection from spreading, we must remove severely infected marijuana leaves. When doing this, it’s important to contain the infection as much as possible. Hence, a plastic bag is useful when collecting the leaves.

Equally important is to seal the bag and shut the garbage disposal lid tightly. This will make sure that the spores are safely contained and will not spread to nearby plants. Finally, don’t forget to treat the plants that held the infected leaves with fungicide.

  • Use Sprays

Commercial products like Mold Control are alternative methods for helping the plants resist powdery mildew. Other preventive sprays are oil from cinnamon, clove, coriander, cottonseed, garlic, and jojoba. What’s great about them is that they can also heal infected plants.

  • Use UVC Light

Using UVC light is an effective method to keep powdery mildew spores from landing on our prized plants. It works by penetrating every space which makes it hard for the spores to attach to the surface and grow.

To get some added benefits, many experienced growers prune some of the fan leaves that don’t get direct light. This way, the plants focus all their energy on growing healthy leaves which often results in giant buds.

  • Water with Ample Light

Overwatering is one of the biggest mistakes any weed grower can make. With excess water, the chances of molds and mildew developing go higher in both indoor and outdoor setups. So, always water at a time of the day when the plants can receive at least five hours of light after that.

  • Other Methods

We can also try one tablespoon of hydrogen peroxide mixed in water and apply it to the leaves. This solution eradicates powdery mildew by oxidizing the fungal cell walls.

Another effective solution that completely kills the fungus is one teaspoon of limonene in one quart of water. Finally, there’s the sulfur burner that contains and controls the problem. Just make sure to keep a good distance from the burner as it can damage our lungs.

Protect Marijuana Plants from Powdery Mildew

Powdery mildew might be one of the most serious marijuana plant conditions but it’s also easy to fix. Just make sure that the grow environment does not promote the growth of fungal spores. So, keep the humidity low and the grow room less crowded.

Moreover, try to apply the preventive methods mentioned in this article to help keep the plants healthy. Similarly, use the treatments we discussed to reduce the symptoms on infected plants.

More importantly, learn to recognize the signs of the disease and act fast to contain it. By doing so, we make sure that the powdery mildew doesn’t get the best of our cannabis plants.

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