Q.white mildew/fungi on leaves
I was reading the article on white fungus on leaves of peonies and it talks about not being able to treat effectively and was wondering does that mean it will come back each year or will the winter kill it off? Once it occurs, is it safe to transplant to better location? Leaves are getting brittle and am afraid the plant is dying.
The good news is that while powdery mildew may be a bit difficult, it certainly is treatable. The most important step is to make the plants as healthy as possible by giving them the best soil, light and water conditions; fertilizing doesn't take the place of these. Healthy plants are rarely troubled by disease. You may want to move your plants to a spot with better sun or soil. The following articles will give the basic on good peony care, and also how to move the plants, or divide them: https://www.gardeningknowhow.com/ornamental/flowers/peony/peony-care.htm
https://www.ipm.iastate.edu/ipm/hortnews/2006/5-17/peonies.html
After you've got healthier peonies, the powdery mildew should be less of a problem. Watch the leaves carefully, and at the first sign of the white stuff, spray with one of the mixtures in the article: https://www.gardeningknowhow.com/ornamental/flowers/peony/powdery-mildew-peonies.htm
You can also contact the Extension Service for advice on powdery mildew treatments available in your area. This link will help you locate one: https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm