Scrape the bark to tell what is dead, brown, and what is alive, green. You have no choice but to cut off dead wood. Young peaches are resilient. It should grow back strongly unless there are deeper issues. You can train and prune the new growth into a balanced tree. It may cost a years worth of growth and fruit but would be better than a totally dead tree. It looks like there might be a canker where the trunk branches.

I have been reading about arid land that is being replanted with trees, and also about the education of local rural people about using mulch to preserve moisture and help fertilize plants. They show how to use small branches stacked around plants, both live and dead. Tree and bush trimmings can be cut up and placed at the base of plants. I have been doing that at my house for a few months. Huge trees (Jacaranda) are always littering the yard with dead twigs. I break them up or cut them up and stack them artistically as mulch, very deeply. It looks pretty good! The loquat trees I did this to are already throwing out a ton of new leaves. Some leaves were also mixed in to the branches or thrown on top.

Thanks for the pics Grant, your dragon fruit is interesting, doesn't look quite like a regular hylocereus undatus (flower is very different). I wonder what the heck it is! At least it is giving you fruit! I've been growing them for several years now and not a single fruit. I can't seem to get them to bloom at a time where I can cross polinate them, come to think of it they don't bloom buch at all. I have one called Haley's Comet that will bloom tomorrow night, but nothing else to polinate it with and I've tried many times to get it to polinate itself, it does not cooperate. I've fertilized mine several times this year with a super bloom type fertilizer, but I don't see that's it's done much good. Maybe we'll get more blooms as it cools down. Kevin

Thanks for your help/comments. I did have the lawn treated with weedkilling herbicide and fed with a granular fertilizer earlier in the year by Greenthumb, a well know lawn maintenance company here in the UK. I was wondering myself whether they sprayed too near the tree as the grassed area probably goes over the top of the tree's roots. However, the same treatment was done last year and the tree looked a whole lot healthier, so it could be the dry Spring and Summer. That said, the tree now looks almost like it is wilting all the time. I have fed it recently with some plant food and that doesn't seem to have improved the situation. I took off the bad branch (sawed it off) and the wood looks in good clean condition. All light beige/brown colour, no signs of disease.