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Powdery mildew on cannabis seeds

Powdery mildew and cannabis

Powdery Mildew ia a fungal disease which mainly attacks plant leaves. There are many species that can be attacked by Powdery Mildew, such as roses, carnations, tomatos, strawberries, cucurbits, apple trees, plum trees and, of course, cannabis. It can be devastating for marijuana if not treated early, since it reaches the buds and ruins its flavour.

The most dangerous Powdery Mildew strains for cannabis plants are Sphaerotheca macularis and Leveillula taurica, which should not be confused with downy mildew, which also attacks the leafs of the plants but, in this case, mainly on the underside of the leaves – while powdery mildew normally infects the surface, although it depends on strains.

Let’s see now the evolution of a powdery mildew infection and what can we do to treat it.

How to identify a powdery mildew infection in cannabis

Detecting this pest is easy, since we’ll quickly notice the growth of white powder stains with cotton like texture on the surface of the largest leaves (formed by the mycelium). These stains are small at first, but if growth conditions are optimal and the infection is not treated they’ll soon cover most of the leaves, even the small sugar leaves of the buds.

At the end of this post you’ll find a picture gallery that will make the identification of powdery mildew much easier.

Cannabis infected with powdery mildew (Picture: Vincent from Alchimia)

As often happens, the presence of this fungus depends on several factors, such as the environment (temperature and humidity), light intensity, nitrogen amount, cannabis variety, etc. Most powdery mildew strains like temperatures between 15 and 28ºC (59ºF-82ºF) and relatively high humidity levels, from 70%.

Spores land on the leaves and, if growth conditions are optimal, start germinating. A thin filament grows from the spores and pierces the plant tissues, absorbing nutrients from the plant cells. Low/high humidity cycles (for example, morning dew and low humidity during the day) are ideal conditions for the germination (high humidity) and growth (low humidity on the leaves) of powdery mildew spores. Thus, poorly ventilated areas – greenhouses, etc. – are perfect for its propagation.

We must also pay attention in indoor grow rooms, where this fungus can quickly propagate if growth conditions are met, also in greenhouses and outdoor crops where environmental conditions often enable its development. Notice that this plant pathogen can complete its life cycle in just 5 days.

First symptoms of powdery mildew

The weakest plants are more sensitive to powdery mildew attacks, as well as those with too much foliar mass or placed in shady areas.

Powdery mildew spores mainly move thanks to aphids and wind, although humans can also act as vectors of this disease.

Prevention of powdery mildew in cannabis plants

First, we should always make sure that our cuttings or seedlings are healthy and free from pests. While this is forgotten most times, it is really important if we want a quality crop. Almost any pest will ruin our product if not treated early and properly.

If we are growing indoors, our growing space should be clean and free from dead plant matter, etc. Humidity levels between 40 and 65% and proper ventilation are very important. Do not wet the leaves unless it’s strictly necessary. If we know that there’s powdery mildew in our area, using spore-proof filters – HEPA – in our ventilation system greatly reduces the possibilities of an infection inside our grow, as well as removing the lower branches and using some type of fungicide regularly (never spray your plants after the first 2 weeks into bloom).

First symptoms of powdery mildew

If we are growing outdoors, it is always important to know if the other plants around our cannabis plants are sensitive to powdery mildew. Normally, this fungi propagates during spring and autumn. If we see traces of powdery mildew in other plants, then we know that we’ll probably have to use some preventive fungicide to protect our plants, otherwise they’ll probably be infected sometime during the bloom period. Whenever possible, we should cover our plants in case of hard rains or regular morning dew and always leave enough space between them to improve ventilation. Rainy areas, with high humidity levels and mist are ideal for powdery mildew propagation.

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Of course, using strains especially resistant to fungi is recommended. The most resistant varieties to powdery mildew from Philosopher Seeds catalogue are:

Treating powdery mildew in cannabis plants

Once the plant is infected, natural fungicides are not very useful, so we’ll have to use systemic fungicides– much more effective – like penconazole (always follow the instructions and respect the safety deadline of the product). Whenever possible, we should adjust the climate conditions of our grow for not favouring any infection.

During the growth phase, we can use horsetail, propolis, potassium soap or sulphur as preventives, also to treat the first symptoms of an infection. As we mentioned, we can also use systemic fungicides, which remain in the plant tissues and protect it for several weeks. Many growers use this type of fungicides right before switching to bloom, so that plants will be protected during the first weeks of this crucial stage. In this way, they greatly reduce the chances of major infections.

Prevention is crucial to avoid major issues

During the flowering period we should always try to avoid using any kinf of plant-protection product. Still, if our plants are infected, we strongly recommend to use these products exclusively during the first 2-3 weeks of bloom, otherwise the flavour of the buds can be ruined, even if we make resin extractions. Both sulphur and potassium soap can leave residues, so we should not use them during this stage.

As we already mentioned, always try to start your crops with strong, healthy plants, it is the best way to avoid future problems. Keeping your mother plants and cuttings/seedling healthy is the best way to ensure a quality harvest.

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We hope this post helped you, if you have further doubts or comments please leave them here, we’ll be pleased to reply them!

Powdery mildew on cannabis seeds

Powdery mildew on buds after harvest is a serious concern for cannabis growers, and for good reason. This severe blight is one of the top causes of cannabis plant destruction. The key to beating this threat is to keep it from getting anywhere near your plants in the first place. Of course, you say, but how? By eradicating it from your grow areas before it can trash your crops. Keep reading to learn how to handle powdery mildew on buds after harvest.

What is Powdery Mildew?

Powdery mildew is a fungal disease that presents as a gray or white powder generated by the fungi spores. It usually first appears on the cannabis leaves and quickly migrates to the marijuana buds. Just before the powder shows up, it can produce small blisters on the tops of leaves. Most often, the powdery mildew spores are spread through the air of the growing areas. Occasionally, they can be spread by humans, tools, or animals brushing against the plants. This airborne pathogen does well in areas of high humidity and cool to moderate temperatures. It also likes crowded growing conditions. Usually, the spores kick off by going after young leaves on mature plants or just younger plants. It will very quickly spread to the entire plant. Besides attacking cannabis leaves, it will also attack the buds. When the affected plants begin to smell like rotten vegetation, they have reached the terminal stage of the infestation. Unfortunately, once powdery mildew is on your plants, it is nearly impossible to remove. Your only chance of saving the crop is by very carefully bagging and removing all infected plants from your grow areas.

Why Powdery Mildew is a Disaster on Buds During and After Harvest

Powdery mildew is a catastrophe to have on your marijuana buds at any time, but especially when you are starting a harvest. The very act of harvesting will spread the spores to any uninfected plants. And once it’s on the buds at harvest, there’s not much you can do to save your crop. You can try very carefully to remove the infected plants from the area. The problem is that every time you touch a plant that’s infected, you can spread the microscopic spores through the air to nearby plants. If the infestation has not spread too far, you can try to very carefully cut out the infected leaves and buds and place them in plastic bags for disposal. You will need to watch your plants closely to make sure you’ve stopped the disease during flowering, too. If you see it has spread to other plants, even after you’ve cut and removed the infected leaves and buds, there’s little you can do but keep cutting and removing. Unfortunately, this is a recipe for heavy damages or totally destroyed crops. The other danger is that you’ve harvested infected buds and unintentionally mixed them in with the remaining good buds during the harvesting process. Naturally, the powdery mildew will continue to spread to other buds even after harvest – and you do not want infected buds in your product.

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Why Powdery Mildew is Important to Prevent Before Infestation

Once your plants are infested your entire crop can be ruined within a few days, especially if it happens at harvest time. That’s why it’s so important to prevent this blight before infestation. You must destroy powdery mildew before it reaches your plants. This might sound impossible, but it’s not. In fact, other cannabis growers use this readily accessible technology now. The secret is setting up an effective air cleaning system. Why? Because most fungal diseases are airborne. In fact, most crop blights are airborne. So it makes sense that a good air cleaning system is the best option to protect your plants.

Using a Powerful Air Sanitation System

Keeping the air clean and free of dangerous airborne pathogens is by far the best way to protect your plants. It is possible to protect your cannabis plants from powdery mildew from seed to harvest. One of the best systems available is the AiroClean420 air purification system. This device uses technology Developed for NASA to scrub the air of pathogens. Here’s how it works: the AiroClean420 system draws air through its sanitation chamber. This is where you can eliminate all the airborne diseases, powdery mildew, spores, fungi, mold, blights, etc. without worrying about harmful chemicals or emissions (AiroClean420 does not produce and/or use ozone or any other chemical or gas). The air exiting the device is 100% free of any and all pathogens.

To learn how the AiroClean420 can prevent powdery mildew from infecting buds during and after harvest, contact us online or call 844-247-3913 and talk to one of our AiroClean420 experts.

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. Powdery Mildew is truly one of the worst of all the fungal diseases that can attack a cannabis plant. If left unchecked it can destroy a full weed crop in only a few days, depending on the severity of the outbreak

Powdery Mildew spores are spread through airborne contamination, which basically means that they float through the air until they come in contact with a plant and take hold from there. The spores can also be by animal or human contact with the plant, so if you think you have an outbreak you should quarantine the affected plant or plants as soon as possible. Be sure to always clean your hands and tools before you come back into contact with healthy plants.

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.

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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.

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. Depending on the severity of a Powdery Mildew outbreak, it can sometimes be difficult to identify – especially in the early stages of an outbreak. You should always keep a close eye on your plants, and keeping a grow log can be a great way of staying on top of any grow room issues

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.

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. You should also try to avoid extreme temperature fluctuations. The optimal temperature range for cannabis growth is 20-30 °C (70-85 °F) for vegetative growth and 18-26 °C (65-80°F) for flowering. The smaller the temperature variation, the harder it will be for Powdery Mildew to take hold.

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:

  • 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. If the infestation has taken a strong grip on multiple plants, it may be best to cut your losses and scrap the entire crop. Trying to maintain a cannabis crop with a high Powdery Mildew infestation rate can put the rest of your grow op at risk.

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.