Powdery mildew is a widespread and easy to recognize plant disease. You’ll know it has become an issue when you see white spots that make your plants appear to be covered in flour. However, the severity of the powdery mildew problem depends on a few things: weather conditions, variety of the plant affected, age and general health of the plant. Typically, the young, fresh growth of a plant is more likely to become infected than older plant tissue. Powdery mildew isn’t just unpleasant to look at, but it can also lead to a loss of your fruit or vegetable crops and even kill entire plants.
Powdery Mildew 101
The plants that are most affected are crowded plants in dry, warm climates with poor air circulation and damp, shaded areas. The most ideal conditions for spore germination is when the relative humidity rises to 90 percent.
To reduce the relative humidity around your plants, it is best to avoid watering them from overhead. If your plants are already infected, you should remove and destroy any of the infected leaves and plant parts and do not compost the infected parts. Selective pruning of overcrowded and overgrown plant material may also help reduce relative humidity and increase air circulation.
If the problem persists, it would be best to consider using a natural fungicide, such as Pure 3-Way, to extinguish all of the powdery mildew that has infected your plants.