2 seperate trees, 2 seperate pots, both stuffed!
Hey, I have 4 bouganvillia bambino's in seperate pots out the front. I neglected them a little and all of them in sync got crusty at the same time.
A quick water and deadwood and they're all OK now, however now I take more care.
Now I'm not suggesting you do that, just that it is possible for them both to do the same thing at the same time.
You need to pull them out of the pots.
My hunch, root bound.
Salix have vigoorous roots like ficus, as they get pot bound they also tend to become hydrophobic (repel water).
So, have a look if you can.
Also, if you get them out of the pot check the pot for drainage, maybe they sat in a well of water if those holes were blocked.
Anyway, bit of a root prune with secatures, cut off any circling roots and thin the mat out, back into the pot with some quality potting mix that hopefully contains some soil and water.
That's what I do, then if they died I'd sleep well at night anyway.

Coz I did all I could.
