No, I doubt it - for two main reasons:So I'm wondering whether yours is looking like this because it's getting too much sun?
Firstly, that particular trellis is in fact part shaded out by the mango tree behind it so it actually gets less sun than my other dragon fruit plants, which happen to be doing much better (probably because I've been giving them more water).
Secondly, commercial plantations don't use shade cloth at all. They plant dragon fruit out in full sun even in the tropics where the sun is very harsh, but the plants get a lot of water, which reinforces my own theory and testing so far.
I'm constantly doing mini-experiments with plants on the go on our property just to see what works and what doesn't. I initially thought the same thing (that sun can affect growth and cause die off in dragon fruit vines) but now I'm convinced it doesn't.
My best guess as to what causes dieback in Pitaya is fungus infection (rust spots) and natural limb die-off due to fractures etc and probably lack of water.