Verticillum wilt.

This is what is left of my Beautiful Catulpa Tree. :o(

After discovering yesterday that there was something wrong with the Catulpa, I have been online to find that the Tree has Verticillum wilt.
I'm so sad & am wondering if it's best to cut it down, but the RHS have suggested watering it with an application of ammonium -based fertiliser as this may stimulate the production of new conducting tissue & help it recover, so it's worth a try. Until I get the fertiliser I'll water it well.
Wish my Catulpa & me "Good Luck" please :o)