Beginner Gardening: Butterfly Weed- rot?, 2 by DonEOshkosh

DonEOshkosh wrote:
I recently retired and plan on spending more time in our garden going forward. I note that our butterfly weed often has branches that seem to just rot off. I had a similar problem with a purple sedum a few years ago- it's totally gone now. Anyway, what can I do to eliminate this problem? The plants are in a mostly clay soil and we have a thin layer of mulch on it. There's never any standing water. I'll attach a picture. Thanks.