Good Morning. My neighbor gave me some peonies last fall. We temporarily planted them in one garden until we extended the garden we wanted to plant them in. We transplanted them this spring. A few bloomed, but some were too small to produce flowers. Now most all of them are covered with powdery mildew (both on the top & bottom of the leaves and stems). The neighbor that gave them to us planted some in her yard too, but none of hers has this mildew. What is the best treatment for this? I've heard about making a Murphy Oil soap, baking soda, and water mixture and heavily spraying them with that, but it just seems that there would be something better to use. If they go untreated, could it harm the other plants I have in that garden (hosta, iris, tulips, fern peonies, other well established peonies, and daylilies). Thank you!!