How to tell if a tree is dead or alive.

I planted 3 fuit trees this spring,a cherry,a plum and a peach.The plum and cherry seem to be fine but the peach (Peregrine) looks dead,it did grow some small leaves but they disappeared and since then,nothing at all. The trees were bought at approx 6ft and were supposed to fruit this year(They didn't).
How can I tell if the peach is dead or not?

Thank you Elbana,I'll try that tomorrow.

You might struggle to get fruit from a peach tree as far north as Yorkshire unless you can give it plenty of protection. The RHS recommends fan-training them against a south or south-west facing wall. Not sure about where you are but up here in West Cumbria we had some strong cold winds in spring which burned a lot of the leaves and that would certainly give the appearance of a dead tree on one that wasn't properly established.

You'll know next spring if it's dead or not.

if it burns its probably dead...