This is our first year in a home with two established peony plants. Today I noticed white spots on the leaves of one of the peony plants (attached a photo). I believe has just finished flowering for the season, and these spots seem to have appeared within the past few days. I am wondering what these are and what I should do. A few weeks ago I had to use a spade to remove an invasive wisteria that was shooting up within the peony plant, sort of near the edge, but unfortunately cutting into the peony root was necessary to remove the wisteria. I wonder if this stressed the peony plant. The plant is in near full sun, and we are in northern VA.

Here is a link that might be useful: