Control Powdery Mildew Disease without Chemicals

Q. What is the best way to get rid of white powdery mildew on my Euonymous plants?

A. The best way is without using chemicals. This requires understanding the conditions which create powdery mildew. The conditions that create powdery mildew are high humidity, splashing water, shade, and lack of air movement across the leaves. Applying chemicals only circumvents the problem and doesn't find a long-term solution to the problem.
 

Powdery mildew on Japanese euonymous and leaf death.

If this advice is followed, there is no need for applying chemicals to control powdery mildew in our climate.

           New location? Make sure your plants are in as much sun as possible. If this is not possible, you might consider a different location for these plants or planting new ones. 

            Splashing water. Do not let water from sprinklers splash on the leaves. Prune the plant to create openings for movement of air between the leaves. If there are trees above the plants, consider removing limbs of these trees that are creating too much shade so that more light reaches the plants.

            Secondly, if these plants are receiving water from sprinklers, switch to drip irrigation. If these plans are being sprinkled with water accidentally, solve this problem so that the leaves do not receive water from sprinklers. 

            Prune for air circulation. Prune these plants deep inside their canopy and remove stems that are too close to others and allow more air movement or wind through these plants. As a last resort, you can use fungicides such as the sulfur based more copper based fungicides. Fungicides used control powdery mildew on roses should also work.