Q.Spiderwort Buds Dry Up, WHY?
I have several (actually too many) spiderwort plants and divide them every 2-3 years. However they now seem to make way too many buds, but almost all of the buds now simply dry up and not bloom. I did note some black area when pulling down a “leaf” and I wonder if they are infected with something. They used to be so beautiful. The one or two buds that do bloom are very small.

Certified GKH Gardening Expert
This does appear to be an infection. This happens when soils remains too moist for too long without a period to dry out.
Fungicides will be in order, here.
These articles will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/special/organic/biofungicide-information.htm