March 29, 2017

White Powdery Mildew And Your Marijuana Plants

March 29, 2017
Picture of cannabis with white powdery mildew.

The road to a successful cannabis harvest is fraught with potential roadblocks, potholes, and if cannabis cultivation is prohibited in your area, traffic stops. Numerous problems can (and will) occur until those trichomes are milky and amber. Aside from improper lighting, fertilizer, pruning, and watering, various types of fungi can plague your fertile pot palace. White powdery mildew is but one concerning fungal example, yet it can be effectively treated. 

White Powdery Mildew on Outdoor and Indoor Pot Plants

White powdery mildew can affect both outdoor and indoor cannabis plants and manifests as fuzzy white spots on weed leaves resembling flour. The leaves themselves may start to wilt and get mottled in appearance while the mildew spreads quickly throughout the plant. White powder on pot plant leaves will destroy other plant parts as well, so it’s very important to stop the mildew from spreading as soon as possible. 

White Powdery Mildew on Soil

Cannabis powdery mildew isn’t your only concern as this mold can also grow in soil. While difficult to detect without a microscope and specific microbiological knowledge, cannabis cultivators can take measures to protect soil from these fungal parasites. You can utilize beneficial fungi such as gliocladium and trichoderma or Bacillus subtilis, a soil-dwelling bacteria with antifungal properties. Copper is an important micronutrient for cannabis cultivation in general, and its inclusion in soil will provide fungicidal properties as well. 

How Long Can Powdery Mildew Spores Live?

Unfortunately, powdery mildew spores can live for 12-20 months in the right environmental conditions. The mildew can spread rapidly since the disease cycle can be completed in as little as 72 hours. However, it usually takes 7-10 days from the time of infection to the development of symptoms and secondary spore production. 

What Causes Powdery Mildew on Pot Plants?

Humidity above 55% and poor ventilation create the ideal environment for spores to develop and flourish. Powdery mildew on pot plants is difficult to detect before it starts growing, and it can make contact with your plants in a variety of ways. With an outdoor grow, white powdery mildew spores may travel through the wind, or they could fly into an indoor grow room through the ventilation system. Spores could also be transported by pets, people, clothing, and/or gardening tools. 

How Do You Prevent Powdery Mildew?

You can prevent powdery mildew weed by keeping humidity below 55% and ensuring proper ventilation. It’s also important to prevent your cannabis plants’ leaves from being overcrowded by allowing some space between them for ventilation. Make close observations of your younger plants as they are at a high risk for powdery mildew. You may notice the smell of powdery mildew before you see it, especially when it is affecting the buds of your cannabis plants. Finally, water your plants when they have at least 5 hours of light after watering to properly dry them out.

Powdery Mildew Health Effects: Is Powdery Mildew Harmful?

Serious powdery mildew effects related to health are likely to occur only with those who are allergic to mold.

Although powdery mildew marijuana doesn’t pose a direct threat to humans, it can provoke a serious reaction in those who are allergic to mold. If you’re not allergic to mold, powdery mildew won’t hurt you if you touch it, but it can be harmful to your cannabis plants, significantly reducing their harvest yield. 

Can Powdery Mildew Be Cured?

You can’t remove white powder mildew on pot plant leaves once it’s taken hold, but you can remove the affected part(s) of the plant or remove the entire plant altogether. However, there are several home remedies and alternative methods you can utilize to control this fungal pest. 

How to Remove Powdery Mildew from Buds

There are several ways to get rid of white powdery mildew on buds). Start with this remedy: 2 teaspoons of organic apple cider vinegar mixed with 1 quart of water. Put this mixture into a spray bottle, and spray the powdery mildew marijuana plants. This will likely kill the mildew and prevent any future spores from developing on your plants.

You can also use a mixture with 1/2 teaspoon of baking soda and 1 quart of water. Spraying sesame oil or fish oil onto affected plants will work similarly. Some cultivators claim a simple mixture of 2 parts milk and 3 parts water will also effectively remove white mildew on buds. 

Other types of oil sprays are less commonly used but can also be effective. These sprays include clove, cottonseed, cinnamon, garlic, and coriander oils.

If one of your cannabis plants has white powdery mildew, remove the affected leaves and seal them in a plastic bag. The sealable bag is vital, as you don’t want their spores to spread anywhere else. Then apply a treatment of some sort, particularly on the stems where the removed leaves used to grow.

What Does Mold Look Like on Pot Plants?

White powdery mildew isn’t the only type of mold capable of attacking your precious pot plants; bud rot and fuzzy white mold are also common invaders as well. All of these fungal pests are easily identified since their white color looks foreign as a strong contrast to the natural green hues of your pot plants. 

Additional Readings on Cultivation

The Weed Blog is a comprehensive source to find reviews of specific top strains of cannabis and online news resources regarding the legalization of marijuana. We are committed to helping you find valuable information about cannabis on our website. With marijuana law constantly changing, learn about the latest legislation from our website and what you can do to help. Otherwise, consider these other top tier articles regarding cannabis cultivation:

Bud Rot and Your Marijuana Plants

How to Kill Spider Mites on Your Marijuana Plants

Cannabis and Humidity 101: The Fundamentals of Grow Room Humidity Control

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