Powdery mildew is very common on pot, marijuana, or cannabis plants. It first appears as white splotches on your leaves, but will spread to the buds and ruin your entire harvest if you don’t take care of it immediately. After you see leaves like this, it is imperative to solve the problem, because you are on the verge of having all your buds covered in powdery mildew. It is most common on shaded areas of the plant. It is most commonly brought into the garden through buying clones at dispensaries that are infected with the spores. Make sure to quarantine new clones to make sure they don’t have any spider mites or powdery mildew. Make sure your grow room has a low humidity, and the temperatures are in the right range. If it gets cool at night when the lights are off, and the humidity rises, you will get powdery mildew. Keeping this disease out of your garden starts with proactively spraying all your plants with neem oil, or other organic treatments. You can also use beneficial bacterias sold in hydroponic stores. The best one is called Serenade. Remove any infected leaves as soon as you find them. Remove dead leaves from the garden, and never allow them to accumulate on the floor.