I think you can make a solution of H2O2 Hydrogen peroxide with water.
Here you go HS. Read this before you chop em down.
Powdery Mildew: Homemade And Organic Remedies
By: Shari Armstrong
Powdery mildew is a common problem in areas that have high humidity. It can affect almost any type of plant, appearing on leaves, flowers, fruits and vegetables. A white or gray powder coats the surface of the plant. If left untreated, it can turn more severe, causing leaves to turn yellow or brown. Many people look to a homemade cure for powdery mildew before turning to fungacides. However, finding a powdery mildew homemade preventer is preferable.
Prevention of powdery mildew
The best way to take care of powdery mildew is by prevention. Be sure to start with healthy plants. One powdery mildew homemade preventer is to simply prune back any dead plant material during the normal pruning time. Do not plant things too close together, to allow ample air circulation around the plants. It is important to not plant in damp shady areas, as that is a prime location for powdery mildew. Another powdery mildew homemade preventer is to avoid using the sprinklers in the evening, so the water doesnt stand on the leaves too long. The water itself doesnt cause more mildew, but it allows it to be transported to the other leaves on the plant easier.
Organic removal of powdery mildew
But, when prevention fails, it is a good idea to try organic removal of powdery mildew first. If you have a case of powdery mildew, be sure not to compost the infected plant parts. There are a few options to try when trying a homemade cure for powdery mildew. One powdery mildew organic remedy is to use dilute solutions of hydrogen peroxide. Spray it on the plants thoroughly about once a week. You can also use a powdery mildew homemade solution of potassium salts. Organic removal of powdery mildew is always preferable to using harsh chemicals on your plants.
There are even some plants, such as the lilac, that can have the powdery mildew on it and it doesnt hurt the plant that much. So using a homemade cure for powdery mildew on the hardier plants isnt necessary.
Another thing to remember is that if one type of plant gets it, that particular strain of powdery mildew wont transfer to the other types of plants. For example, it wont go from the roses to the lilacs, just to the other roses.
The best powdery mildew homemade preventer is maintain the proper moisture level, without raising the humidity around the plants too high. This, along with careful annual pruning will go a long way toward keeping your plants healthy and beautiful.
Hope this helps bud. 1BMM