I've noticed odd brown nodules on an otherwise healthy wisteria in full bloom. The nodules are covering the stem and pick off easily. Inside they are dry and powdery. Should I be worried about this? The wisteria grows well every year and is approx 16 years old.
It appears to be spores of some kind. Scale insects would leave a sticky residue.
Watch for that.
You could treat with Neem Oil.
Here are a couple of links.