Any experienced cannabis grower has likely encountered one of the most common fungal diseases for plants – Powdery Mildew (PM).

Powdery mildew is a white, powder-like fungal disease that reproduces on the leaves of many different kinds of plant species. Thriving in high-humidity environments and moderate temperatures, PM can severely stunt your plant’s growth and yields by blocking your leaves ability to absorb sunlight and convert it to energy, a.k.a. photosynthesis.

Some facts about powdery mildew…

  • Powdery mildew reproduces sexually and asexually. It is a fast-growing fungi that is spread by spores. These spores most commonly infect susceptible plants via airborne transmission.
  • PM will quickly move throughout your plant, smothering it in white mildew – many instances in just a few days time. Left untreated, powdery mildew will effectively ruin your weed harvest.
  • This fungi can be spread through the wind, hitch-hike on your clothes or pets, and come through air-ventilation systems. Wooly aphids are also a known common transmitter of this infection.
  • Common plant hosts are cabbages, tomatoes, cucumbers and beans – even trees such as apple, pear and Japanese maple trees can carry PM. Make sure to eliminate ALL of your local powdery mildew, not just selectively your cannabis plants.
  • Powdery mildew will literally suck the life out of your marijuana – once identified you must take action ASAP. As PM takes over, you will see your whole plant yellowing and falling into slow, stunted growth.
  • If you grow indoors, be sure to clean all your grow room with CANNA ZYMES, making sure to cover all surfaces and areas the fungi may be able to reside, then fog.

Stay away from sulfur and copperremedies. Although these often work, they are TOXIC and not fit for smoking purposes. Once upon a time, a budding Blueberry Hash plant was sprayed down with a sulfur spray – it sure did get rid of the powdery mildew. A white sulfur residue was left behind that was impossible to remove, even after rinsing. Harvested, the resulting buds were completely unsmokeable – marijuana smelled and tasted precisely as if lighting a match – Costly Fail!

White powdery mildew is extremely difficult to detect before it starts growing on your plants. That is because it can make contact with your plants in a variety of ways. It might travel via the wind with outdoor marijuana plants, or perhaps it flew into your grow room through your ventilation system. It could also be transported by pets, people, clothing, or tools.

Once the spores attach to your marijuana plants, they might not become active for a period of time (until the environment is perfect for them to grow). That can make it even harder to determine how the spores got to your plants to begin with.

This is why it is critical to ensure that you are preventing the development of white powdery mildew from the start. If you aren’t concerned enough about the development of white powdery mildew to take preventative measures, you should adjust your attitude.

White powdery mildew can have extremely adverse effects on the health of your plant, including substantially slowing down the process of photosynthesis. A slow process of photosynthesis means a poor harvest, so it’s crucial that you don’t allow it to develop. It is the type of pest that isn’t terribly uncommon, meaning you should already be keeping an eye out for it before there is even any sign of it.

Recognizing powdery mildew

White powdery mildew generally develops on the leaves of marijuana plants in the form of round, fuzzy spots that resemble flour. The leaves themselves could start to wilt and get mottled in appearance, with the mold spreading quickly throughout the plant. It will destroy the parts that it reaches, so it’s very important to stop it from spreading as soon as possible.

It’s easy to identify white powdery mildew because it looks incredibly white compared to the green plant. Once you identify it, it’s important to act fast. Of course, the spores of white powdery mildew are harder (or even impossible) to spot.

Basically, if you see the leaves on your marijuana plants turning pale or having white patches, or specifically affected in one area (i.e. upper part of the plant with newer leaves, or lower part with older leaves), white powdery mildew is likely the culprit. Spots, mottled or mosaic appearance, and the wilting and drooping of your marijuana plants’ leaves are also symptoms of white powdery mildew.

Risk factors

High humidity, whether it’s in an outdoor setting or an indoor one, is more likely to attract powdery mildew. High humidity is quantified as 55% or greater. Poor ventilation combined with high humidity is a recipe for disaster when it comes to the development of white powdery mildew.

Additional risk factors include plants’ leaves being overcrowded, meaning they are touching one another. The same goes for plants that are overcrowded with one another — if they are touching, they are too close. This means there is not enough space for air to properly ventilate through them.

Generally speaking, younger plants are at a higher risk for developing white powdery mildew. They will attack leaves, stems, and buds in equal measure. You may notice the smell of powdery mildew before you see it, especially when it is affecting the buds of your marijuana plants.

THE ONLY SAFE, NON-TOXIC, NATURAL way to remove/eradicate white powdery mildew once it has taken hold, is CANNA ZYMES. Without using CANNA ZYMES you will simply have to remove that part of the plant, or the entire plant to prevent it from spreading to your other plants. After a while, white powdery mildew will kill off your entire crop.