SoCalGardenNut said:Most likely botrytis, I had this happened to me this year.
SonoveShakespeare said:This reminds me, I have a peony plant that has powdery mildew on it's leaves.
I tend to give my perennials around my back deck a little sprinkle (or as I call it a rain) with the hose after I water and rain my potted annuals on the deck. Would that be the cause of powdery mildew on one of my peony plants???
anyagoro said:Anna, How old is your peony? I would not give up on it, just cut the most effected leaves and wait until next year.
It says here not to water the leaves from above, which is what I did!
LizinElizabeth said:I don't think your problem is botrytis, Anna. Look up peony blotch, also called peony measles. It's still a fungal issue like botrytis but not as bad. I don't think your problem with the bud/bloom if from peony blotch though so there could be another issue or it could be weather related. Your post made it sound like this is an established plant, is that correct? Some lactifloras especially don't like it when the temps rise too fast, if you had a hotter than normal spring—or the opposite, a later than normal freeze once buds started to form—I'd expect to see issues with blooming.
Fungal issues can be more prevalent overall when plants are overcrowded and don't get a lot of airflow. Mulch contributes to the problem as does overhead watering and too much fertilizer. You might want to treat the area with a pre-emergent fungicide really early next spring and even something gentle like the milk/water drench once foliage is forming to treat preventatively, once the damage is there you really can't do anything to make it look better but most of the time it doesn't kill the root. I wouldn't ignore a fungal issue though—they're unsightly to begin with but the foliage damage prevents proper photosynthesis so the roots aren't getting fed as well on top of the ugliness. Hope it does much better next spring!
LizinElizabeth said:It's so late in the season, I wouldn't bother treating them unless you start to have rotting stems and those I'd treat by cutting them back to healthy looking pieces with sterilized cutters. Treating when fungal issues are already wide spread doesn't do much good, the treatments are preventative rather than restorative. This fall cut all herbaceous foliage and stems down to an inch of the ground, I'd wash whatever you use to cut them with a bleach/water soaked cloth between cuts and ABSOLUTELY between plants, try not to let infected foliage touch the ground and dispose of it in the trash, don't compost or keep on site.