Thank you!! :)

is it hit with a lawn sprinkler?

ken

No! I actually watered my lawn for the first time just yesterday..it's been a while since we've had rain and figured time to give the lawn a drink. But nothing before then?

Water the base of the plant, not the leaves, long and slowly. If you aren't sure if it needs water, stick your finger into the soil. If it's dry water it. The disease is stressing it, so it doesn't need more stress from being overly dry, and at least here, it's been very dry, with less than half the usual moisture for June following a quite dry spring.

Thank you thank you Babs....for dispelling the oft-seen myth that powdery mildew is the result of excess moisture and wet foliage. Indeed, you've correctly nailed the point that it is specifically drought-stressed plants that are most susceptible to this malady. Hardly ever hear anyone get that right!

And while the advice to not wet the foliage may still apply-after all, we haven't necessarily nailed down the ID of whatever is happening here-it is also true that the fungus responsible for powdery mildew-unlike most other fungal pathogens-does not require wet foliage to get going.