I can't see a photo, but when did you plant them, and where are you?
It's been a pretty dry summer for most people in NZ...
Young trees can need regular watering through at least their first summer.
Are the trees mulched? Thick mulch, NOT touching the trunk, really helps reduce evaporation and competition.
I'd give them a really long, deep water at the roots(like leave the hose on low under the mulch for a couple of hours).
Plums especially, like quite a bit of water.

Thanks for your reply feijoas. I thought I had uploaded a photo. Funny you mentioned mulch, I mulched them earlier today with washed seaweed. We have marigolds planted around the base of the trees as well.

Here is the other plum. I'm a real newbie, this is my first garden.

And one of two red peaches. If its water problems and I get them back to health will they fruit as normal or have I stuffed them? I have a root stock with two varietys of apple on it and its looking real good right next to these trees as well. When I searched online, google coughed up all this stuff on fireblight, which I'm hoping its not.

Fire blight doesn't affect peach and plum. Your trees probably just need water. First year trees are much more sensitive to lack of water because they have a small root system. They will not compete with weeds or marigolds. Water them good now and they still might bear fruit next year. If not the year after.