Hi there, my husband brought me a mini patio orchard of 4 fruit trees.

leaves have just started to come out for the first time and i ave just noticed the leaves on the young sunburst cherry tree are nw going brown at the edges and curling.. please have a look at the attachments to see what i mean.
can anybody help me with this and tell me what it is? causing it? what can i do about it?
many thanks

thank you so much for all your replies and generous help!!