Question Dragon fruit vine sudden die back problem

I've never grown Pitaya but it looks like some type of fungal disease. I'd suggest pruning all infected parts, enclose in plastic and remove from the site. Try a broad spectrum fungicide or phosphoric acid. If I remember, I'll ask the nurseryman I know if he is familiar with diseases of Pitaya.

 

Hey Mark,
How did you go with the pitaya fungus? I've got some yellow/orange fungal looking spots on mine at the moment, what did you use to treat it?

 

Cactoblastis grubs &/or Cochineal insects!
Cactoblastis was introduced into Australia to combat the scourge of prickly pear in the mid 1920's.
Along with the Cochineal, it now infests any type of cactus, sucking it dry or chewing out the flesh from inside & allowing all other forms of disease in as well.

http://www.northwestweeds.com.au/sample-page/cactoblastis-biocontrol/
https://en.wikipedia.org/wiki/Cactoblastis_cactorum

 

Thanks! I think that may be my problem! I think I may have some of the egg sticks on the effected cacti, I thought they were roots because it's a transplant.
The plant is probably lost now hey?

 

If those old brown leaves are the total of your plant then yes it is lost.
However if there are lower or other branches that are not brown but still have some greenness to them then a good spray with pyrethrum should do the job along with some TLC in the form of a good fertilizer & some nice new composty soil.
Maybe even some seaweed solution sprayed on each week.

 

I can't seem to upload a pic, my pics are too big!

I did check the cacti for what I thought might be egg sticks, but thankfully they weren't! They were just roots

 

Hoping this works

 

This is the main stem :-/