She is at it again and I notice the time stamp.. same time of year, beginning of June. . I guess maybe too wet of soil for her liking. Her flowers were really pathetic this year and now with her leaves turning brown again now I am guessing I should expect the same this next winter. I think she is needs some help. I might go ahead and find some chemicals to help her out. She must be in a bad location so she is going to need some extra help. She is way too big to move.

They really don't like wet feet. If you can't move her, she may always have problems.

when we moved in (2013) she seemed fine, last year she started looking like crap. I dont remember her looking bad in 2014, but maybe I was not paying attention.

I did finally find this after much searching tonight. Most website will tell you the tree is relatively pest free, but I found this.

http://mrec.ifas.ufl.edu/lso/SCOUT/key.pdf

Key Plants, Key Diseases Key Insects/Mites Key Nematodes

Tabebuia
Tabebuia spp.

Algal spot - Cephaleuros virescens
Leaf spots - Cercospora,
Corynespora spp.
Black twig beetle
Scale, several species
Tabebuia leafhopper
Holopothrips near inquilinus
Root-knot nematodes
Meloidogyne spp.

maybe I can find something that can help her out.

I know this post is a few years old, but I came across it as I was researching the exact same issue with my tabebuia. I just planted mine a few months ago and although it's still sprouting new growth the leaves in the lower half of the tree are beginning to turn yellow/brown (just like in the picture above) and seem to be slowly working their way up the tree. Did you ever discover the issue with your tabebuia? Thanks!

Have the same problem

My tabebuia turn totally brown after being totally green less than a week earlier.

Help

Fruiting bodies of some mushrooms occur in arcs or rings called fairy rings. The mycelium starts from a mushroom spores falling in a favorable spot and producing strands (hyphae) that grow out in all directions, eventually forming a circular mat of underground hyphal threads. Fruiting bodies, produced near the edge of this mat, may widen the ring for hundreds of years.