Growing cannabis comes with some interesting challenges. This is not meant to discourage you. Being aware of the potential problems, and learning how to work through them, is one of the facets of growing that make it so intriguing and fulfilling. One of the most common problems is Powdery Mildew (PM), also known as White Powdery Mildew, or Powdery Mold. You can identify powdery mildew by carefully inspecting your plants on a regular basis. It appears as white powdery fungal specs that are growing on the surface of the leaves. PM is a fungal disease that affects many types of crops. It can spread very quickly, and slows development, growth, and eventually, if left untreated, can kill your plant. The best way to prevent powdery mildew from damaging your crop is to know and understand the causes, and act very quickly to eradicate it if detected.
Causes of PM
- Powdery mildew can be introduced into the growing environment via a single spore. The spore can cling to your clothes and transfer onto your plants. It’s important to wear clean clothes when working in your grow area.
- Too much humidity in a closed area.
- Lack of good airflow between your plants, their branches, and their leaves.
- Lack of light penetrating into a majority of the cannabis plant; i.e. typically bushier plants such as indicas are prone to powdery mildew if the shadier, darker leaves of the plant aren’t receiving proper light.
- Weak genetics – unfortunately runts or sick plants are less resistant to powdery mildew.
Ways to Prevent PM
- Ensure proper airflow around your crop. If growing indoors, this can be done with fans and ventilation systems. If growing outdoors, choose a good location and provide proper spacing between your plants.
- Try to lower the humidity around your cannabis plants. This is especially important when your plants begin to flower or bloom. Indoors, this can be done with dehumidifiers. Outdoors, you are at the mercy of the weather, but growing in a greenhouse can help immensely in humidity management.
- Using natural and organic preventative chemical sprays such as Neem Oil, which are available for purchase at hydroponics stores. It is strongly advised to stick to natural and organic solutions. And remember you can only spray your plants during their vegetative stages of growth, not during their flowering cycle. Using chemical pesticides and mold control chemicals can easily ruin your crop, and make it unsafe for medical consumption.
Ways to Combat PM
- Remove the infected part of the plant (leaves, branches, etc.), or even better, the entire plant from the rest of the crop. This must be done carefully to ensure that mildew spores do not spread to the other plants. Take a plastic bag, cover the infected sites or plants, remove them, and discard far away from your grow area.
- During the vegetative stages of your plants, spray them with organic natural solutions, such as neem oil, to help prevent or kill off the powdery mildew. You can find a variety of natural, organic products that fight powdery mildew at a hydroponics store and online.
- During the flowering cycle of your plants, treating PM is a little trickier. Removal of the infected plant is perhaps the best way to deal with PM, but it is possible to tediously hand treat specific leaves and branches with solutions to kill the fungi. Affected buds should be discarded, as they will no longer be safe for consumption.