Almost all of my bee-balm and some of my zinnias develop what looks like white mold spots on their leaves. Those affected doesn’t seem to affect growth at all, but is it something to worry about or cure?
Bee Balm, some Zinnia, Lilac and other specie exhibit some form of powdery mildew late in the season.
All are different forms of this common fungus – different fungus with the same symptoms…
Not an issue, other than the disfigured appearance. This is an inherent weakness with the individual plant, but often times does not outright kill the plant.
I am not distracted by this in a mixed ‘meadow’ setting, but when I have one Jacob Kline Bee-balm in a border that begins to bloom & has no leaves that look good – disappointing!